From a82dadfbae74916aecdd10121cc0177fd8162b90 Mon Sep 17 00:00:00 2001
From: Yann Collet <cyan@fb.com>
Date: Tue, 8 Aug 2017 17:43:11 -0700
Subject: added dictID inside LZ4F_frameInfo_t

Compressor can set dictID on LZ4F_compressBegin()
Decompressor can retrieve it using LZ4F_getFrameInfo()
---
 doc/lz4_Frame_format.md |   3 +-
 lib/lz4frame.c          |  41 ++++++++----
 lib/lz4frame.h          |   5 +-
 tests/frametest.c       | 161 +++++++++++++++++++++++-------------------------
 4 files changed, 108 insertions(+), 102 deletions(-)

diff --git a/doc/lz4_Frame_format.md b/doc/lz4_Frame_format.md
index bae2b06..77454b2 100644
--- a/doc/lz4_Frame_format.md
+++ b/doc/lz4_Frame_format.md
@@ -237,8 +237,7 @@ __Header Checksum__
 
 One-byte checksum of combined descriptor fields, including optional ones.
 The value is the second byte of `xxh32()` : ` (xxh32()>>8) & 0xFF `
-using zero as a seed,
-and the full Frame Descriptor as an input
+using zero as a seed, and the full Frame Descriptor as an input
 (including optional fields when they are present).
 A wrong checksum indicates an error in the descriptor.
 Header checksum is informational and can be skipped.
diff --git a/lib/lz4frame.c b/lib/lz4frame.c
index 994cc8b..c2d6d5c 100644
--- a/lib/lz4frame.c
+++ b/lib/lz4frame.c
@@ -158,7 +158,7 @@ static void LZ4F_writeLE64 (void* dst, U64 value64)
 #define LZ4F_BLOCKSIZEID_DEFAULT LZ4F_max64KB
 
 static const size_t minFHSize = 7;
-static const size_t maxFHSize = LZ4F_HEADER_SIZE_MAX;   /* 15 */
+static const size_t maxFHSize = LZ4F_HEADER_SIZE_MAX;   /* 19 */
 static const size_t BHSize = 4;
 
 
@@ -291,7 +291,7 @@ static size_t LZ4F_compressBound_internal(size_t srcSize,
 size_t LZ4F_compressFrameBound(size_t srcSize, const LZ4F_preferences_t* preferencesPtr)
 {
     LZ4F_preferences_t prefs;
-    size_t const headerSize = maxFHSize;      /* max header size, including magic number and frame content size */
+    size_t const headerSize = maxFHSize;      /* max header size, including optional fields */
 
     if (preferencesPtr!=NULL) prefs = *preferencesPtr;
     else memset(&prefs, 0, sizeof(prefs));
@@ -470,9 +470,10 @@ size_t LZ4F_compressBegin(LZ4F_cctx* cctxPtr, void* dstBuffer, size_t dstCapacit
 
     /* FLG Byte */
     *dstPtr++ = (BYTE)(((1 & _2BITS) << 6)    /* Version('01') */
-        + ((cctxPtr->prefs.frameInfo.blockMode & _1BIT ) << 5)    /* Block mode */
+        + ((cctxPtr->prefs.frameInfo.blockMode & _1BIT ) << 5)  /* Block mode */
+        + ((cctxPtr->prefs.frameInfo.contentSize > 0) << 3)     /* Frame content size */
         + ((cctxPtr->prefs.frameInfo.contentChecksumFlag & _1BIT ) << 2)   /* Frame checksum */
-        + ((cctxPtr->prefs.frameInfo.contentSize > 0) << 3));   /* Frame content size */
+        +  (cctxPtr->prefs.frameInfo.dictID > 0) );   /* Dictionary ID */
     /* BD Byte */
     *dstPtr++ = (BYTE)((cctxPtr->prefs.frameInfo.blockSizeID & _3BITS) << 4);
     /* Optional Frame content size field */
@@ -481,6 +482,11 @@ size_t LZ4F_compressBegin(LZ4F_cctx* cctxPtr, void* dstBuffer, size_t dstCapacit
         dstPtr += 8;
         cctxPtr->totalInSize = 0;
     }
+    /* Optional dictionary ID field */
+    if (cctxPtr->prefs.frameInfo.dictID) {
+        LZ4F_writeLE32(dstPtr, cctxPtr->prefs.frameInfo.dictID);
+        dstPtr += 4;
+    }
     /* CRC Byte */
     *dstPtr = LZ4F_headerChecksum(headerStart, dstPtr - headerStart);
     dstPtr++;
@@ -817,12 +823,14 @@ static size_t LZ4F_headerSize(const void* src, size_t srcSize)
     if ((LZ4F_readLE32(src) & 0xFFFFFFF0U) == LZ4F_MAGIC_SKIPPABLE_START) return 8;
 
     /* control magic number */
-    if (LZ4F_readLE32(src) != LZ4F_MAGICNUMBER) return err0r(LZ4F_ERROR_frameType_unknown);
+    if (LZ4F_readLE32(src) != LZ4F_MAGICNUMBER)
+        return err0r(LZ4F_ERROR_frameType_unknown);
 
     /* Frame Header Size */
     {   BYTE const FLG = ((const BYTE*)src)[4];
         U32 const contentSizeFlag = (FLG>>3) & _1BIT;
-        return contentSizeFlag ? maxFHSize : minFHSize;
+        U32 const dictIDFlag = FLG & _1BIT;
+        return minFHSize + (contentSizeFlag*8) + (dictIDFlag*4);
     }
 }
 
@@ -837,7 +845,7 @@ static size_t LZ4F_headerSize(const void* src, size_t srcSize)
  */
 static size_t LZ4F_decodeHeader(LZ4F_dctx* dctxPtr, const void* src, size_t srcSize)
 {
-    unsigned blockMode, contentSizeFlag, contentChecksumFlag, blockSizeID;
+    unsigned blockMode, contentSizeFlag, contentChecksumFlag, dictIDFlag, blockSizeID;
     size_t frameHeaderSize;
     const BYTE* srcPtr = (const BYTE*)src;
 
@@ -860,7 +868,8 @@ static size_t LZ4F_decodeHeader(LZ4F_dctx* dctxPtr, const void* src, size_t srcS
     }
 
     /* control magic number */
-    if (LZ4F_readLE32(srcPtr) != LZ4F_MAGICNUMBER) return err0r(LZ4F_ERROR_frameType_unknown);
+    if (LZ4F_readLE32(srcPtr) != LZ4F_MAGICNUMBER)
+        return err0r(LZ4F_ERROR_frameType_unknown);
     dctxPtr->frameInfo.frameType = LZ4F_frame;
 
     /* Flags */
@@ -870,14 +879,15 @@ static size_t LZ4F_decodeHeader(LZ4F_dctx* dctxPtr, const void* src, size_t srcS
         blockMode = (FLG>>5) & _1BIT;
         contentSizeFlag = (FLG>>3) & _1BIT;
         contentChecksumFlag = (FLG>>2) & _1BIT;
+        dictIDFlag = FLG & _1BIT;
         /* validate */
-        if (((FLG>>0)&_2BITS) != 0) return err0r(LZ4F_ERROR_reservedFlag_set); /* Reserved bits */
+        if (((FLG>>1)&_1BIT) != 0) return err0r(LZ4F_ERROR_reservedFlag_set); /* Reserved bits */
         if (version != 1) return err0r(LZ4F_ERROR_headerVersion_wrong);        /* Version Number, only supported value */
         if (blockChecksumFlag != 0) return err0r(LZ4F_ERROR_blockChecksum_unsupported); /* Not supported for the time being */
     }
 
     /* Frame Header Size */
-    frameHeaderSize = contentSizeFlag ? maxFHSize : minFHSize;
+    frameHeaderSize = minFHSize + (contentSizeFlag*8) + (dictIDFlag*4);
 
     if (srcSize < frameHeaderSize) {
         /* not enough input to fully decode frame header */
@@ -898,8 +908,10 @@ static size_t LZ4F_decodeHeader(LZ4F_dctx* dctxPtr, const void* src, size_t srcS
     }
 
     /* check header */
-    { BYTE const HC = LZ4F_headerChecksum(srcPtr+4, frameHeaderSize-5);
-      if (HC != srcPtr[frameHeaderSize-1]) return err0r(LZ4F_ERROR_headerChecksum_invalid); }
+    {   BYTE const HC = LZ4F_headerChecksum(srcPtr+4, frameHeaderSize-5);
+        if (HC != srcPtr[frameHeaderSize-1])
+            return err0r(LZ4F_ERROR_headerChecksum_invalid);
+    }
 
     /* save */
     dctxPtr->frameInfo.blockMode = (LZ4F_blockMode_t)blockMode;
@@ -907,7 +919,10 @@ static size_t LZ4F_decodeHeader(LZ4F_dctx* dctxPtr, const void* src, size_t srcS
     dctxPtr->frameInfo.blockSizeID = (LZ4F_blockSizeID_t)blockSizeID;
     dctxPtr->maxBlockSize = LZ4F_getBlockSize(blockSizeID);
     if (contentSizeFlag)
-        dctxPtr->frameRemainingSize = dctxPtr->frameInfo.contentSize = LZ4F_readLE64(srcPtr+6);
+        dctxPtr->frameRemainingSize =
+            dctxPtr->frameInfo.contentSize = LZ4F_readLE64(srcPtr+6);
+    if (dictIDFlag)
+        dctxPtr->frameInfo.dictID = LZ4F_readLE32(srcPtr + frameHeaderSize - 5);
 
     dctxPtr->dStage = dstage_init;
 
diff --git a/lib/lz4frame.h b/lib/lz4frame.h
index dd2be58..0efe220 100644
--- a/lib/lz4frame.h
+++ b/lib/lz4frame.h
@@ -162,7 +162,8 @@ typedef struct {
   LZ4F_contentChecksum_t contentChecksumFlag;   /* noContentChecksum, contentChecksumEnabled ; 0 == default  */
   LZ4F_frameType_t       frameType;             /* LZ4F_frame, skippableFrame ; 0 == default */
   unsigned long long     contentSize;           /* Size of uncompressed (original) content ; 0 == unknown */
-  unsigned               reserved[2];           /* must be zero for forward compatibility */
+  unsigned               dictID;                /* Dictionary ID, sent by the compressor, to help the decoder select the right dictionary; 0 == no dictionary used */
+  unsigned               reserved[1];           /* must be zero for forward compatibility */
 } LZ4F_frameInfo_t;
 
 /*! LZ4F_preferences_t :
@@ -228,7 +229,7 @@ LZ4FLIB_API LZ4F_errorCode_t LZ4F_freeCompressionContext(LZ4F_cctx* cctx);
 
 /*----    Compression    ----*/
 
-#define LZ4F_HEADER_SIZE_MAX 15
+#define LZ4F_HEADER_SIZE_MAX 19
 /*! LZ4F_compressBegin() :
  * will write the frame header into dstBuffer.
  * dstCapacity must be large enough to store the header. Maximum header size is LZ4F_HEADER_SIZE_MAX bytes.
diff --git a/tests/frametest.c b/tests/frametest.c
index 0dadf9f..02d7e5b 100644
--- a/tests/frametest.c
+++ b/tests/frametest.c
@@ -164,6 +164,9 @@ static unsigned FUZ_highbit(U32 v32)
 /*-*******************************************************
 *  Tests
 *********************************************************/
+#define CHECK_V(v,f) v = f; if (LZ4F_isError(v)) goto _output_error
+#define CHECK(f)   { LZ4F_errorCode_t const CHECK_V(err_ , f); }
+
 int basicTests(U32 seed, double compressibility)
 {
 #define COMPRESSIBLE_NOISE_LENGTH (2 MB)
@@ -197,24 +200,20 @@ int basicTests(U32 seed, double compressibility)
     /* Special case : null-content frame */
     testSize = 0;
     DISPLAYLEVEL(3, "LZ4F_compressFrame, compress null content : ");
-    cSize = LZ4F_compressFrame(compressedBuffer, LZ4F_compressFrameBound(testSize, NULL), CNBuffer, testSize, NULL);
-    if (LZ4F_isError(cSize)) goto _output_error;
+    CHECK_V(cSize, LZ4F_compressFrame(compressedBuffer, LZ4F_compressFrameBound(testSize, NULL), CNBuffer, testSize, NULL));
     DISPLAYLEVEL(3, "null content encoded into a %u bytes frame \n", (unsigned)cSize);
 
     DISPLAYLEVEL(3, "LZ4F_createDecompressionContext \n");
-    { LZ4F_errorCode_t const errorCode = LZ4F_createDecompressionContext(&dCtx, LZ4F_VERSION);
-      if (LZ4F_isError(errorCode)) goto _output_error; }
+    CHECK ( LZ4F_createDecompressionContext(&dCtx, LZ4F_VERSION) );
 
     DISPLAYLEVEL(3, "LZ4F_getFrameInfo on null-content frame (#157) \n");
     {   size_t avail_in = cSize;
         LZ4F_frameInfo_t frame_info;
-        LZ4F_errorCode_t const errorCode = LZ4F_getFrameInfo(dCtx, &frame_info, compressedBuffer, &avail_in);
-        if (LZ4F_isError(errorCode)) goto _output_error;
+        CHECK( LZ4F_getFrameInfo(dCtx, &frame_info, compressedBuffer, &avail_in) );
     }
 
     DISPLAYLEVEL(3, "LZ4F_freeDecompressionContext \n");
-    { LZ4F_errorCode_t const errorCode = LZ4F_freeDecompressionContext(dCtx);
-      if (LZ4F_isError(errorCode)) goto _output_error; }
+    CHECK( LZ4F_freeDecompressionContext(dCtx) );
     dCtx = NULL;
 
     /* test one-pass frame compression */
@@ -224,26 +223,22 @@ int basicTests(U32 seed, double compressibility)
     {   LZ4F_preferences_t fastCompressPrefs;
         memset(&fastCompressPrefs, 0, sizeof(fastCompressPrefs));
         fastCompressPrefs.compressionLevel = -3;
-        cSize = LZ4F_compressFrame(compressedBuffer, LZ4F_compressFrameBound(testSize, NULL), CNBuffer, testSize, &fastCompressPrefs);
-        if (LZ4F_isError(cSize)) goto _output_error;
+        CHECK_V(cSize, LZ4F_compressFrame(compressedBuffer, LZ4F_compressFrameBound(testSize, NULL), CNBuffer, testSize, &fastCompressPrefs));
         DISPLAYLEVEL(3, "Compressed %u bytes into a %u bytes frame \n", (U32)testSize, (U32)cSize);
     }
 
     DISPLAYLEVEL(3, "LZ4F_compressFrame, using default preferences : ");
-    cSize = LZ4F_compressFrame(compressedBuffer, LZ4F_compressFrameBound(testSize, NULL), CNBuffer, testSize, NULL);
-    if (LZ4F_isError(cSize)) goto _output_error;
+    CHECK_V(cSize, LZ4F_compressFrame(compressedBuffer, LZ4F_compressFrameBound(testSize, NULL), CNBuffer, testSize, NULL));
     DISPLAYLEVEL(3, "Compressed %u bytes into a %u bytes frame \n", (U32)testSize, (U32)cSize);
 
     DISPLAYLEVEL(3, "Decompression test : \n");
     {   size_t decodedBufferSize = COMPRESSIBLE_NOISE_LENGTH;
         size_t compressedBufferSize = cSize;
 
-        LZ4F_errorCode_t errorCode = LZ4F_createDecompressionContext(&dCtx, LZ4F_VERSION);
-        if (LZ4F_isError(errorCode)) goto _output_error;
+        CHECK( LZ4F_createDecompressionContext(&dCtx, LZ4F_VERSION) );
 
         DISPLAYLEVEL(3, "Single Pass decompression : ");
-        { size_t const decompressError = LZ4F_decompress(dCtx, decodedBuffer, &decodedBufferSize, compressedBuffer, &compressedBufferSize, NULL);
-          if (LZ4F_isError(decompressError)) goto _output_error; }
+        CHECK( LZ4F_decompress(dCtx, decodedBuffer, &decodedBufferSize, compressedBuffer, &compressedBufferSize, NULL) );
         { U64 const crcDest = XXH64(decodedBuffer, decodedBufferSize, 1);
           if (crcDest != crcOrig) goto _output_error; }
         DISPLAYLEVEL(3, "Regenerated %u bytes \n", (U32)decodedBufferSize);
@@ -257,8 +252,7 @@ int basicTests(U32 seed, double compressibility)
             BYTE* const oend = (BYTE*)decodedBuffer + COMPRESSIBLE_NOISE_LENGTH;
             size_t decResult, oSize = COMPRESSIBLE_NOISE_LENGTH;
             DISPLAYLEVEL(3, "Missing last %u bytes : ", (U32)missingBytes);
-            decResult = LZ4F_decompress(dCtx, op, &oSize, cBuff, &iSize, NULL);
-            if (LZ4F_isError(decResult)) goto _output_error;
+            CHECK_V(decResult, LZ4F_decompress(dCtx, op, &oSize, cBuff, &iSize, NULL));
             if (decResult != missingBytes) {
                 DISPLAY("%u bytes missing != %u bytes requested \n", (U32)missingBytes, (U32)decResult);
                 goto _output_error;
@@ -282,9 +276,9 @@ int basicTests(U32 seed, double compressibility)
             const BYTE* ip = (BYTE*)compressedBuffer;
 
             DISPLAYLEVEL(3, "Start by feeding 0 bytes, to get next input size : ");
-            errorCode = LZ4F_decompress(dCtx, NULL, &oSize, ip, &iSize, NULL);
-            if (LZ4F_isError(errorCode)) goto _output_error;
-            DISPLAYLEVEL(3, " %u  \n", (unsigned)errorCode);
+            CHECK( LZ4F_decompress(dCtx, NULL, &oSize, ip, &iSize, NULL) );
+            //DISPLAYLEVEL(3, " %u  \n", (unsigned)errorCode);
+            DISPLAYLEVEL(3, " OK  \n");
 
             DISPLAYLEVEL(3, "LZ4F_getFrameInfo on zero-size input : ");
             {   size_t nullSize = 0;
@@ -309,8 +303,7 @@ int basicTests(U32 seed, double compressibility)
 
             DISPLAYLEVEL(3, "LZ4F_getFrameInfo on enough input : ");
             iSize = 15 - iSize;
-            errorCode = LZ4F_getFrameInfo(dCtx, &fi, ip, &iSize);
-            if (LZ4F_isError(errorCode)) goto _output_error;
+            CHECK( LZ4F_getFrameInfo(dCtx, &fi, ip, &iSize) );
             DISPLAYLEVEL(3, " correctly decoded \n");
             ip += iSize;
         }
@@ -342,8 +335,7 @@ int basicTests(U32 seed, double compressibility)
             while (ip < iend) {
                 size_t oSize = oend-op;
                 size_t iSize = 1;
-                errorCode = LZ4F_decompress(dCtx, op, &oSize, ip, &iSize, NULL);
-                if (LZ4F_isError(errorCode)) goto _output_error;
+                CHECK( LZ4F_decompress(dCtx, op, &oSize, ip, &iSize, NULL) );
                 op += oSize;
                 ip += iSize;
             }
@@ -356,21 +348,18 @@ int basicTests(U32 seed, double compressibility)
     DISPLAYLEVEL(3, "Using 64 KB block : ");
     prefs.frameInfo.blockSizeID = LZ4F_max64KB;
     prefs.frameInfo.contentChecksumFlag = LZ4F_contentChecksumEnabled;
-    cSize = LZ4F_compressFrame(compressedBuffer, LZ4F_compressFrameBound(testSize, &prefs), CNBuffer, testSize, &prefs);
-    if (LZ4F_isError(cSize)) goto _output_error;
+    CHECK_V(cSize, LZ4F_compressFrame(compressedBuffer, LZ4F_compressFrameBound(testSize, &prefs), CNBuffer, testSize, &prefs));
     DISPLAYLEVEL(3, "Compressed %i bytes into a %i bytes frame \n", (int)testSize, (int)cSize);
 
     DISPLAYLEVEL(3, "without checksum : ");
     prefs.frameInfo.contentChecksumFlag = LZ4F_noContentChecksum;
-    cSize = LZ4F_compressFrame(compressedBuffer, LZ4F_compressFrameBound(testSize, &prefs), CNBuffer, testSize, &prefs);
-    if (LZ4F_isError(cSize)) goto _output_error;
+    CHECK_V(cSize, LZ4F_compressFrame(compressedBuffer, LZ4F_compressFrameBound(testSize, &prefs), CNBuffer, testSize, &prefs));
     DISPLAYLEVEL(3, "Compressed %i bytes into a %i bytes frame \n", (int)testSize, (int)cSize);
 
     DISPLAYLEVEL(3, "Using 256 KB block : ");
     prefs.frameInfo.blockSizeID = LZ4F_max256KB;
     prefs.frameInfo.contentChecksumFlag = LZ4F_contentChecksumEnabled;
-    cSize = LZ4F_compressFrame(compressedBuffer, LZ4F_compressFrameBound(testSize, &prefs), CNBuffer, testSize, &prefs);
-    if (LZ4F_isError(cSize)) goto _output_error;
+    CHECK_V(cSize, LZ4F_compressFrame(compressedBuffer, LZ4F_compressFrameBound(testSize, &prefs), CNBuffer, testSize, &prefs));
     DISPLAYLEVEL(3, "Compressed %i bytes into a %i bytes frame \n", (int)testSize, (int)cSize);
 
     DISPLAYLEVEL(3, "Decompression test : \n");
@@ -388,8 +377,7 @@ int basicTests(U32 seed, double compressibility)
             size_t iSize = (FUZ_rand(&randState) & ((1<<nbBits)-1)) + 1;
             size_t oSize = oend-op;
             if (iSize > (size_t)(iend-ip)) iSize = iend-ip;
-            { size_t const decompressError = LZ4F_decompress(dCtx, op, &oSize, ip, &iSize, NULL);
-              if (LZ4F_isError(decompressError)) goto _output_error; }
+            CHECK( LZ4F_decompress(dCtx, op, &oSize, ip, &iSize, NULL) );
             op += oSize;
             ip += iSize;
         }
@@ -399,28 +387,24 @@ int basicTests(U32 seed, double compressibility)
             DISPLAYLEVEL(3, "Regenerated %u bytes \n", (U32)decodedSize);
          }
 
-        { LZ4F_errorCode_t const freeError = LZ4F_freeDecompressionContext(dCtx);
-          if (LZ4F_isError(freeError)) goto _output_error; }
+        CHECK( LZ4F_freeDecompressionContext(dCtx) );
         dCtx = NULL;
     }
 
     DISPLAYLEVEL(3, "without checksum : ");
     prefs.frameInfo.contentChecksumFlag = LZ4F_noContentChecksum;
-    cSize = LZ4F_compressFrame(compressedBuffer, LZ4F_compressFrameBound(testSize, &prefs), CNBuffer, testSize, &prefs);
-    if (LZ4F_isError(cSize)) goto _output_error;
+    CHECK_V(cSize, LZ4F_compressFrame(compressedBuffer, LZ4F_compressFrameBound(testSize, &prefs), CNBuffer, testSize, &prefs) );
     DISPLAYLEVEL(3, "Compressed %i bytes into a %i bytes frame \n", (int)testSize, (int)cSize);
 
     DISPLAYLEVEL(3, "Using 1 MB block : ");
     prefs.frameInfo.blockSizeID = LZ4F_max1MB;
     prefs.frameInfo.contentChecksumFlag = LZ4F_contentChecksumEnabled;
-    cSize = LZ4F_compressFrame(compressedBuffer, LZ4F_compressFrameBound(testSize, &prefs), CNBuffer, testSize, &prefs);
-    if (LZ4F_isError(cSize)) goto _output_error;
+    CHECK_V(cSize, LZ4F_compressFrame(compressedBuffer, LZ4F_compressFrameBound(testSize, &prefs), CNBuffer, testSize, &prefs) );
     DISPLAYLEVEL(3, "Compressed %i bytes into a %i bytes frame \n", (int)testSize, (int)cSize);
 
     DISPLAYLEVEL(3, "without checksum : ");
     prefs.frameInfo.contentChecksumFlag = LZ4F_noContentChecksum;
-    cSize = LZ4F_compressFrame(compressedBuffer, LZ4F_compressFrameBound(testSize, &prefs), CNBuffer, testSize, &prefs);
-    if (LZ4F_isError(cSize)) goto _output_error;
+    CHECK_V(cSize, LZ4F_compressFrame(compressedBuffer, LZ4F_compressFrameBound(testSize, &prefs), CNBuffer, testSize, &prefs) );
     DISPLAYLEVEL(3, "Compressed %i bytes into a %i bytes frame \n", (int)testSize, (int)cSize);
 
     DISPLAYLEVEL(3, "Using 4 MB block : ");
@@ -428,8 +412,7 @@ int basicTests(U32 seed, double compressibility)
     prefs.frameInfo.contentChecksumFlag = LZ4F_contentChecksumEnabled;
     {   size_t const dstCapacity = LZ4F_compressFrameBound(testSize, &prefs);
         DISPLAYLEVEL(4, "dstCapacity = %u  ; ", (U32)dstCapacity)
-        cSize = LZ4F_compressFrame(compressedBuffer, dstCapacity, CNBuffer, testSize, &prefs);
-        if (LZ4F_isError(cSize)) goto _output_error;
+        CHECK_V(cSize, LZ4F_compressFrame(compressedBuffer, dstCapacity, CNBuffer, testSize, &prefs) );
         DISPLAYLEVEL(3, "Compressed %u bytes into a %u bytes frame \n", (U32)testSize, (U32)cSize);
     }
 
@@ -437,61 +420,72 @@ int basicTests(U32 seed, double compressibility)
     prefs.frameInfo.contentChecksumFlag = LZ4F_noContentChecksum;
     {   size_t const dstCapacity = LZ4F_compressFrameBound(testSize, &prefs);
         DISPLAYLEVEL(4, "dstCapacity = %u  ; ", (U32)dstCapacity)
-        cSize = LZ4F_compressFrame(compressedBuffer, dstCapacity, CNBuffer, testSize, &prefs);
-        if (LZ4F_isError(cSize)) goto _output_error;
+        CHECK_V(cSize, LZ4F_compressFrame(compressedBuffer, dstCapacity, CNBuffer, testSize, &prefs) );
         DISPLAYLEVEL(3, "Compressed %u bytes into a %u bytes frame \n", (U32)testSize, (U32)cSize);
     }
 
-    {   size_t errorCode;
+    /* frame content size tests */
+    {   size_t cErr;
         BYTE* const ostart = (BYTE*)compressedBuffer;
         BYTE* op = ostart;
-        errorCode = LZ4F_createCompressionContext(&cctx, LZ4F_VERSION);
-        if (LZ4F_isError(errorCode)) goto _output_error;
+        CHECK( LZ4F_createCompressionContext(&cctx, LZ4F_VERSION) );
 
         DISPLAYLEVEL(3, "compress without frameSize : ");
         memset(&(prefs.frameInfo), 0, sizeof(prefs.frameInfo));
-        errorCode = LZ4F_compressBegin(cctx, compressedBuffer, testSize, &prefs);
-        if (LZ4F_isError(errorCode)) goto _output_error;
-        op += errorCode;
-        errorCode = LZ4F_compressUpdate(cctx, op, LZ4F_compressBound(testSize, &prefs), CNBuffer, testSize, NULL);
-        if (LZ4F_isError(errorCode)) goto _output_error;
-        op += errorCode;
-        errorCode = LZ4F_compressEnd(cctx, compressedBuffer, testSize, NULL);
-        if (LZ4F_isError(errorCode)) goto _output_error;
+        CHECK_V(cErr, LZ4F_compressBegin(cctx, compressedBuffer, testSize, &prefs));
+        op += cErr;
+        CHECK_V(cErr, LZ4F_compressUpdate(cctx, op, LZ4F_compressBound(testSize, &prefs), CNBuffer, testSize, NULL));
+        op += cErr;
+        CHECK( LZ4F_compressEnd(cctx, compressedBuffer, testSize, NULL) );
         DISPLAYLEVEL(3, "Compressed %i bytes into a %i bytes frame \n", (int)testSize, (int)(op-ostart));
 
         DISPLAYLEVEL(3, "compress with frameSize : ");
         prefs.frameInfo.contentSize = testSize;
         op = ostart;
-        errorCode = LZ4F_compressBegin(cctx, compressedBuffer, testSize, &prefs);
-        if (LZ4F_isError(errorCode)) goto _output_error;
-        op += errorCode;
-        errorCode = LZ4F_compressUpdate(cctx, op, LZ4F_compressBound(testSize, &prefs), CNBuffer, testSize, NULL);
-        if (LZ4F_isError(errorCode)) goto _output_error;
-        op += errorCode;
-        errorCode = LZ4F_compressEnd(cctx, compressedBuffer, testSize, NULL);
-        if (LZ4F_isError(errorCode)) goto _output_error;
+        CHECK_V(cErr, LZ4F_compressBegin(cctx, compressedBuffer, testSize, &prefs));
+        op += cErr;
+        CHECK_V(cErr, LZ4F_compressUpdate(cctx, op, LZ4F_compressBound(testSize, &prefs), CNBuffer, testSize, NULL));
+        op += cErr;
+        CHECK( LZ4F_compressEnd(cctx, compressedBuffer, testSize, NULL) );
         DISPLAYLEVEL(3, "Compressed %i bytes into a %i bytes frame \n", (int)testSize, (int)(op-ostart));
 
         DISPLAYLEVEL(3, "compress with wrong frameSize : ");
         prefs.frameInfo.contentSize = testSize+1;
         op = ostart;
-        errorCode = LZ4F_compressBegin(cctx, compressedBuffer, testSize, &prefs);
-        if (LZ4F_isError(errorCode)) goto _output_error;
-        op += errorCode;
-        errorCode = LZ4F_compressUpdate(cctx, op, LZ4F_compressBound(testSize, &prefs), CNBuffer, testSize, NULL);
-        if (LZ4F_isError(errorCode)) goto _output_error;
-        op += errorCode;
-        errorCode = LZ4F_compressEnd(cctx, op, testSize, NULL);
-        if (LZ4F_isError(errorCode)) { DISPLAYLEVEL(3, "Error correctly detected : %s \n", LZ4F_getErrorName(errorCode)); }
-        else
-            goto _output_error;
-
-        errorCode = LZ4F_freeCompressionContext(cctx);
-        if (LZ4F_isError(errorCode)) goto _output_error;
+        CHECK_V(cErr, LZ4F_compressBegin(cctx, compressedBuffer, testSize, &prefs));
+        op += cErr;
+        CHECK_V(cErr, LZ4F_compressUpdate(cctx, op, LZ4F_compressBound(testSize, &prefs), CNBuffer, testSize, NULL));
+        op += cErr;
+        cErr = LZ4F_compressEnd(cctx, op, testSize, NULL);
+        if (!LZ4F_isError(cErr)) goto _output_error;
+        DISPLAYLEVEL(3, "Error correctly detected : %s \n", LZ4F_getErrorName(cErr));
+
+        CHECK( LZ4F_freeCompressionContext(cctx) );
         cctx = NULL;
     }
 
+    /* dictID tests */
+    {   size_t cErr;
+        U32 const dictID = 0x99;
+        CHECK( LZ4F_createCompressionContext(&cctx, LZ4F_VERSION) );
+
+        DISPLAYLEVEL(3, "insert a dictID : ");
+        memset(&prefs.frameInfo, 0, sizeof(prefs.frameInfo));
+        prefs.frameInfo.dictID = dictID;
+        CHECK_V(cErr, LZ4F_compressBegin(cctx, compressedBuffer, testSize, &prefs));
+        DISPLAYLEVEL(3, "created frame header of size %i bytes  \n", (int)cErr);
+
+        DISPLAYLEVEL(3, "read a dictID : ");
+        CHECK( LZ4F_createDecompressionContext(&dCtx, LZ4F_VERSION) );
+        memset(&prefs.frameInfo, 0, sizeof(prefs.frameInfo));
+        CHECK( LZ4F_getFrameInfo(dCtx, &prefs.frameInfo, compressedBuffer, &cErr) );
+        if (prefs.frameInfo.dictID != dictID) goto _output_error;
+        DISPLAYLEVEL(3, "%u \n", (U32)prefs.frameInfo.dictID);
+
+        CHECK( LZ4F_freeCompressionContext(cctx) ); cctx = NULL;
+        CHECK( LZ4F_freeDecompressionContext(dCtx) ); dCtx = NULL;
+    }
+
     DISPLAYLEVEL(3, "Skippable frame test : \n");
     {   size_t decodedBufferSize = COMPRESSIBLE_NOISE_LENGTH;
         unsigned maxBits = FUZ_highbit((U32)decodedBufferSize);
@@ -500,8 +494,7 @@ int basicTests(U32 seed, double compressibility)
         BYTE* ip = (BYTE*)compressedBuffer;
         BYTE* iend = (BYTE*)compressedBuffer + cSize + 8;
 
-        LZ4F_errorCode_t errorCode = LZ4F_createDecompressionContext(&dCtx, LZ4F_VERSION);
-        if (LZ4F_isError(errorCode)) goto _output_error;
+        CHECK( LZ4F_createDecompressionContext(&dCtx, LZ4F_VERSION) );
 
         /* generate skippable frame */
         FUZ_writeLE32(ip, LZ4F_MAGIC_SKIPPABLE_START);
@@ -513,8 +506,7 @@ int basicTests(U32 seed, double compressibility)
             size_t iSize = (FUZ_rand(&randState) & ((1<<nbBits)-1)) + 1;
             size_t oSize = oend-op;
             if (iSize > (size_t)(iend-ip)) iSize = iend-ip;
-            errorCode = LZ4F_decompress(dCtx, op, &oSize, ip, &iSize, NULL);
-            if (LZ4F_isError(errorCode)) goto _output_error;
+            CHECK( LZ4F_decompress(dCtx, op, &oSize, ip, &iSize, NULL) );
             op += oSize;
             ip += iSize;
         }
@@ -533,8 +525,7 @@ int basicTests(U32 seed, double compressibility)
             size_t iSize = (FUZ_rand(&randState) & ((1<<nbBits)-1)) + 1;
             size_t oSize = oend-op;
             if (iSize > (size_t)(iend-ip)) iSize = iend-ip;
-            errorCode = LZ4F_decompress(dCtx, op, &oSize, ip, &iSize, NULL);
-            if (LZ4F_isError(errorCode)) goto _output_error;
+            CHECK( LZ4F_decompress(dCtx, op, &oSize, ip, &iSize, NULL) );
             op += oSize;
             ip += iSize;
         }
@@ -550,8 +541,7 @@ int basicTests(U32 seed, double compressibility)
             size_t iSize = 10;
             size_t oSize = 10;
             if (iSize > (size_t)(iend-ip)) iSize = iend-ip;
-            errorCode = LZ4F_decompress(dCtx, op, &oSize, ip, &iSize, NULL);
-            if (LZ4F_isError(errorCode)) goto _output_error;
+            CHECK( LZ4F_decompress(dCtx, op, &oSize, ip, &iSize, NULL) );
             op += oSize;
             ip += iSize;
         }
@@ -603,6 +593,7 @@ int fuzzerTests(U32 seed, unsigned nbTests, unsigned startTest, double compressi
     size_t result;
     clock_t const startClock = clock();
     clock_t const clockDuration = duration_s * CLOCKS_PER_SEC;
+#   undef CHECK
 #   define CHECK(cond, ...) if (cond) { DISPLAY("Error => "); DISPLAY(__VA_ARGS__); \
                             DISPLAY(" (seed %u, test nb %u)  \n", seed, testNb); goto _output_error; }
 
-- 
cgit v0.12


From 1d1737aaf28c60d3cf6950b545f6a844afe422c0 Mon Sep 17 00:00:00 2001
From: Yann Collet <cyan@fb.com>
Date: Wed, 9 Aug 2017 12:29:38 -0700
Subject: fixed frameCompress example

---
 doc/lz4frame_manual.html |  35 +--
 examples/frameCompress.c | 537 ++++++++++++++++++++++++-----------------------
 2 files changed, 288 insertions(+), 284 deletions(-)

diff --git a/doc/lz4frame_manual.html b/doc/lz4frame_manual.html
index 87750a1..e6873c1 100644
--- a/doc/lz4frame_manual.html
+++ b/doc/lz4frame_manual.html
@@ -74,7 +74,8 @@
   LZ4F_contentChecksum_t contentChecksumFlag;   </b>/* noContentChecksum, contentChecksumEnabled ; 0 == default  */<b>
   LZ4F_frameType_t       frameType;             </b>/* LZ4F_frame, skippableFrame ; 0 == default */<b>
   unsigned long long     contentSize;           </b>/* Size of uncompressed (original) content ; 0 == unknown */<b>
-  unsigned               reserved[2];           </b>/* must be zero for forward compatibility */<b>
+  unsigned               dictID;                </b>/* Dictionary ID, sent by the compressor, to help the decoder select the right dictionary; 0 == no dictionary used */<b>
+  unsigned               reserved[1];           </b>/* must be zero for forward compatibility */<b>
 } LZ4F_frameInfo_t;
 </b><p> makes it possible to supply detailed frame parameters to the stream interface.
  It's not required to set all fields, as long as the structure was initially memset() to zero.
@@ -186,15 +187,15 @@ LZ4F_errorCode_t LZ4F_freeCompressionContext(LZ4F_cctx* cctx);
 <a name="Chapter9"></a><h2>Decompression functions</h2><pre></pre>
 
 <pre><b>typedef struct {
-  unsigned stableDst;       </b>/* guarantee that decompressed data will still be there on next function calls (avoid storage into tmp buffers) */<b>
+  unsigned stableDst;    </b>/* pledge that at least 64KB+64Bytes of previously decompressed data remain unmodifed where it was decoded. This optimization skips storage operations in tmp buffers */<b>
   unsigned reserved[3];
 } LZ4F_decompressOptions_t;
 </b></pre><BR>
 <pre><b>LZ4F_errorCode_t LZ4F_createDecompressionContext(LZ4F_dctx** dctxPtr, unsigned version);
 LZ4F_errorCode_t LZ4F_freeDecompressionContext(LZ4F_dctx* dctx);
-</b><p> Create an LZ4F_decompressionContext_t object, which will be used to track all decompression operations.
- The version provided MUST be LZ4F_VERSION. It is intended to track potential breaking differences between different versions.
- The function will provide a pointer to a fully allocated and initialized LZ4F_decompressionContext_t object.
+</b><p> Create an LZ4F_dctx object, to track all decompression operations.
+ The version provided MUST be LZ4F_VERSION.
+ The function provides a pointer to an allocated and initialized LZ4F_dctx object.
  The result is an errorCode, which can be tested using LZ4F_isError().
  dctx memory can be released using LZ4F_freeDecompressionContext();
  The result of LZ4F_freeDecompressionContext() is indicative of the current state of decompressionContext when being released.
@@ -208,20 +209,22 @@ LZ4F_errorCode_t LZ4F_freeDecompressionContext(LZ4F_dctx* dctx);
                                      LZ4F_frameInfo_t* frameInfoPtr,
                                      const void* srcBuffer, size_t* srcSizePtr);
 </b><p> This function extracts frame parameters (such as max blockSize, frame checksum, etc.).
- Its usage is optional. Extracted information can be useful for allocation purposes, typically.
+ Its usage is optional.
+ Extracted information can typically be useful for allocation purposes.
  This function works in 2 situations :
-   - At the beginning of a new frame, in which case it will decode this information from `srcBuffer`, and start the decoding process.
+   - At the beginning of a new frame, in which case
+     it will decode information from `srcBuffer`, starting the decoding process.
      Input size must be large enough to successfully decode the entire frame header.
      Frame header size is variable, but is guaranteed to be <= LZ4F_HEADER_SIZE_MAX bytes.
      It's allowed to provide more input data than this minimum.
    - After decoding has been started.
      In which case, no input is read, frame parameters are extracted from dctx.
-     If decoding has just started, but not yet extracted information from header, LZ4F_getFrameInfo() will fail.
+   - If decoding has barely started, but not yet extracted information from header, LZ4F_getFrameInfo() will fail.
  The number of bytes consumed from srcBuffer will be updated within *srcSizePtr (necessarily <= original value).
  Decompression must resume from (srcBuffer + *srcSizePtr).
  @return : an hint about how many srcSize bytes LZ4F_decompress() expects for next call,
            or an error code which can be tested using LZ4F_isError()
- note 1 : in case of error, dctx is not modified. Decoding operations can resume from where they stopped.
+ note 1 : in case of error, dctx is not modified. Decoding operation can resume safely.
  note 2 : frame parameters are *copied into* an already allocated LZ4F_frameInfo_t structure.
  
 </p></pre><BR>
@@ -230,18 +233,18 @@ LZ4F_errorCode_t LZ4F_freeDecompressionContext(LZ4F_dctx* dctx);
                                    void* dstBuffer, size_t* dstSizePtr,
                                    const void* srcBuffer, size_t* srcSizePtr,
                                    const LZ4F_decompressOptions_t* dOptPtr);
-</b><p> Call this function repetitively to regenerate data compressed within `srcBuffer`.
+</b><p> Call this function repetitively to regenerate compressed data from `srcBuffer`.
  The function will attempt to decode up to *srcSizePtr bytes from srcBuffer, into dstBuffer of capacity *dstSizePtr.
 
- The number of bytes regenerated into dstBuffer will be provided within *dstSizePtr (necessarily <= original value).
+ The number of bytes regenerated into dstBuffer is provided within *dstSizePtr (necessarily <= original value).
 
- The number of bytes read from srcBuffer will be provided within *srcSizePtr (necessarily <= original value).
- Number of bytes read can be < number of bytes provided, meaning there is some more data to decode.
+ The number of bytes consumed from srcBuffer is provided within *srcSizePtr (necessarily <= original value).
+ Number of bytes consumed can be < number of bytes provided.
  It typically happens when dstBuffer is not large enough to contain all decoded data.
- Remaining data will have to be presented again in a subsequent invocation.
+ Unconsumed source data must be presented again in subsequent invocations.
 
  `dstBuffer` content is expected to be flushed between each invocation, as its content will be overwritten.
- `dstBuffer` can be changed at will between each consecutive function invocation.
+ `dstBuffer` itself can be changed at will between each consecutive function invocation.
 
  @return is an hint of how many `srcSize` bytes LZ4F_decompress() expects for next call.
  Schematically, it's the size of the current (or remaining) compressed block + header of next block.
@@ -259,7 +262,7 @@ LZ4F_errorCode_t LZ4F_freeDecompressionContext(LZ4F_dctx* dctx);
 </b><p>  In case of an error, the context is left in "undefined" state.
   In which case, it's necessary to reset it, before re-using it.
   This method can also be used to abruptly stop an unfinished decompression,
-  and start a new with the same context. 
+  and start a new one using the same context. 
 </p></pre><BR>
 
 </html>
diff --git a/examples/frameCompress.c b/examples/frameCompress.c
index 75f1576..0a42fe3 100644
--- a/examples/frameCompress.c
+++ b/examples/frameCompress.c
@@ -13,299 +13,300 @@
 #define LZ4_FOOTER_SIZE 4
 
 static const LZ4F_preferences_t lz4_preferences = {
-	{ LZ4F_max256KB, LZ4F_blockLinked, LZ4F_noContentChecksum, LZ4F_frame, 0, { 0, 0 } },
-	0,   /* compression level */
-	0,   /* autoflush */
-	{ 0, 0, 0, 0 },  /* reserved, must be set to 0 */
+    { LZ4F_max256KB, LZ4F_blockLinked, LZ4F_noContentChecksum, LZ4F_frame,
+      0 /* content size unknown */, 0 /* no dictID */ , { 0 } /* reserved */ },
+    0,   /* compression level */
+    0,   /* autoflush */
+    { 0, 0, 0, 0 },  /* reserved, must be set to 0 */
 };
 
 static size_t compress_file(FILE *in, FILE *out, size_t *size_in, size_t *size_out) {
-	LZ4F_errorCode_t r;
-	LZ4F_compressionContext_t ctx;
-	char *src, *buf = NULL;
-	size_t size, n, k, count_in = 0, count_out, offset = 0, frame_size;
-
-	r = LZ4F_createCompressionContext(&ctx, LZ4F_VERSION);
-	if (LZ4F_isError(r)) {
-		printf("Failed to create context: error %zu\n", r);
-		return 1;
-	}
-	r = 1;
-
-	src = malloc(BUF_SIZE);
-	if (!src) {
-		printf("Not enough memory\n");
-		goto cleanup;
-	}
-
-	frame_size = LZ4F_compressBound(BUF_SIZE, &lz4_preferences);
-	size =  frame_size + LZ4_HEADER_SIZE + LZ4_FOOTER_SIZE;
-	buf = malloc(size);
-	if (!buf) {
-		printf("Not enough memory\n");
-		goto cleanup;
-	}
-
-	n = offset = count_out = LZ4F_compressBegin(ctx, buf, size, &lz4_preferences);
-	if (LZ4F_isError(n)) {
-		printf("Failed to start compression: error %zu\n", n);
-		goto cleanup;
-	}
-
-	printf("Buffer size is %zu bytes, header size %zu bytes\n", size, n);
-
-	for (;;) {
-		k = fread(src, 1, BUF_SIZE, in);
-		if (k == 0)
-			break;
-		count_in += k;
-
-		n = LZ4F_compressUpdate(ctx, buf + offset, size - offset, src, k, NULL);
-		if (LZ4F_isError(n)) {
-			printf("Compression failed: error %zu\n", n);
-			goto cleanup;
-		}
-
-		offset += n;
-		count_out += n;
-		if (size - offset < frame_size + LZ4_FOOTER_SIZE) {
-			printf("Writing %zu bytes\n", offset);
-
-			k = fwrite(buf, 1, offset, out);
-			if (k < offset) {
-				if (ferror(out))
-					printf("Write failed\n");
-				else
-					printf("Short write\n");
-				goto cleanup;
-			}
-
-			offset = 0;
-		}
-	}
-
-	n = LZ4F_compressEnd(ctx, buf + offset, size - offset, NULL);
-	if (LZ4F_isError(n)) {
-		printf("Failed to end compression: error %zu\n", n);
-		goto cleanup;
-	}
-
-	offset += n;
-	count_out += n;
-	printf("Writing %zu bytes\n", offset);
-
-	k = fwrite(buf, 1, offset, out);
-	if (k < offset) {
-		if (ferror(out))
-			printf("Write failed\n");
-		else
-			printf("Short write\n");
-		goto cleanup;
-	}
-
-	*size_in = count_in;
-	*size_out = count_out;
-	r = 0;
+    LZ4F_errorCode_t r;
+    LZ4F_compressionContext_t ctx;
+    char *src, *buf = NULL;
+    size_t size, n, k, count_in = 0, count_out, offset = 0, frame_size;
+
+    r = LZ4F_createCompressionContext(&ctx, LZ4F_VERSION);
+    if (LZ4F_isError(r)) {
+        printf("Failed to create context: error %zu\n", r);
+        return 1;
+    }
+    r = 1;  /* function result; 1 == error, by default (early exit) */
+
+    src = malloc(BUF_SIZE);
+    if (!src) {
+        printf("Not enough memory\n");
+        goto cleanup;
+    }
+
+    frame_size = LZ4F_compressBound(BUF_SIZE, &lz4_preferences);
+    size =  frame_size + LZ4_HEADER_SIZE + LZ4_FOOTER_SIZE;
+    buf = malloc(size);
+    if (!buf) {
+        printf("Not enough memory\n");
+        goto cleanup;
+    }
+
+    n = offset = count_out = LZ4F_compressBegin(ctx, buf, size, &lz4_preferences);
+    if (LZ4F_isError(n)) {
+        printf("Failed to start compression: error %zu\n", n);
+        goto cleanup;
+    }
+
+    printf("Buffer size is %zu bytes, header size %zu bytes\n", size, n);
+
+    for (;;) {
+        k = fread(src, 1, BUF_SIZE, in);
+        if (k == 0)
+            break;
+        count_in += k;
+
+        n = LZ4F_compressUpdate(ctx, buf + offset, size - offset, src, k, NULL);
+        if (LZ4F_isError(n)) {
+            printf("Compression failed: error %zu\n", n);
+            goto cleanup;
+        }
+
+        offset += n;
+        count_out += n;
+        if (size - offset < frame_size + LZ4_FOOTER_SIZE) {
+            printf("Writing %zu bytes\n", offset);
+
+            k = fwrite(buf, 1, offset, out);
+            if (k < offset) {
+                if (ferror(out))
+                    printf("Write failed\n");
+                else
+                    printf("Short write\n");
+                goto cleanup;
+            }
+
+            offset = 0;
+        }
+    }
+
+    n = LZ4F_compressEnd(ctx, buf + offset, size - offset, NULL);
+    if (LZ4F_isError(n)) {
+        printf("Failed to end compression: error %zu\n", n);
+        goto cleanup;
+    }
+
+    offset += n;
+    count_out += n;
+    printf("Writing %zu bytes\n", offset);
+
+    k = fwrite(buf, 1, offset, out);
+    if (k < offset) {
+        if (ferror(out))
+            printf("Write failed\n");
+        else
+            printf("Short write\n");
+        goto cleanup;
+    }
+
+    *size_in = count_in;
+    *size_out = count_out;
+    r = 0;
  cleanup:
-	if (ctx)
-		LZ4F_freeCompressionContext(ctx);
-	free(src);
-	free(buf);
-	return r;
+    if (ctx)
+        LZ4F_freeCompressionContext(ctx);
+    free(src);
+    free(buf);
+    return r;
 }
 
 static size_t get_block_size(const LZ4F_frameInfo_t* info) {
-	switch (info->blockSizeID) {
+    switch (info->blockSizeID) {
         case LZ4F_default:
-		case LZ4F_max64KB:  return 1 << 16;
-		case LZ4F_max256KB: return 1 << 18;
-		case LZ4F_max1MB:   return 1 << 20;
-		case LZ4F_max4MB:   return 1 << 22;
-		default:
-			printf("Impossible unless more block sizes are allowed\n");
-			exit(1);
-	}
+        case LZ4F_max64KB:  return 1 << 16;
+        case LZ4F_max256KB: return 1 << 18;
+        case LZ4F_max1MB:   return 1 << 20;
+        case LZ4F_max4MB:   return 1 << 22;
+        default:
+            printf("Impossible unless more block sizes are allowed\n");
+            exit(1);
+    }
 }
 
 static size_t decompress_file(FILE *in, FILE *out) {
-	void* const src = malloc(BUF_SIZE);
-	void* dst = NULL;
-	size_t dstCapacity = 0;
-	LZ4F_dctx *dctx = NULL;
-	size_t ret;
+    void* const src = malloc(BUF_SIZE);
+    void* dst = NULL;
+    size_t dstCapacity = 0;
+    LZ4F_dctx *dctx = NULL;
+    size_t ret;
 
-	/* Initialization */
+    /* Initialization */
     if (!src) { perror("decompress_file(src)"); goto cleanup; }
-	ret = LZ4F_createDecompressionContext(&dctx, 100);
-	if (LZ4F_isError(ret)) {
-		printf("LZ4F_dctx creation error: %s\n", LZ4F_getErrorName(ret));
-		goto cleanup;
-	}
-
-	/* Decompression */
-	ret = 1;
-	while (ret != 0) {
-		/* Load more input */
-		size_t srcSize = fread(src, 1, BUF_SIZE, in);
-		void* srcPtr = src;
-		void* srcEnd = srcPtr + srcSize;
-		if (srcSize == 0 || ferror(in)) {
-			printf("Decompress: not enough input or error reading file\n");
-			goto cleanup;
-		}
-		/* Allocate destination buffer if it isn't already */
-		if (!dst) {
-			LZ4F_frameInfo_t info;
-			ret = LZ4F_getFrameInfo(dctx, &info, src, &srcSize);
-			if (LZ4F_isError(ret)) {
-				printf("LZ4F_getFrameInfo error: %s\n", LZ4F_getErrorName(ret));
-				goto cleanup;
-			}
-			/* Allocating enough space for an entire block isn't necessary for
-			 * correctness, but it allows some memcpy's to be elided.
-			 */
-			dstCapacity = get_block_size(&info);
-			dst = malloc(dstCapacity);
+    ret = LZ4F_createDecompressionContext(&dctx, 100);
+    if (LZ4F_isError(ret)) {
+        printf("LZ4F_dctx creation error: %s\n", LZ4F_getErrorName(ret));
+        goto cleanup;
+    }
+
+    /* Decompression */
+    ret = 1;
+    while (ret != 0) {
+        /* Load more input */
+        size_t srcSize = fread(src, 1, BUF_SIZE, in);
+        void* srcPtr = src;
+        void* srcEnd = srcPtr + srcSize;
+        if (srcSize == 0 || ferror(in)) {
+            printf("Decompress: not enough input or error reading file\n");
+            goto cleanup;
+        }
+        /* Allocate destination buffer if it isn't already */
+        if (!dst) {
+            LZ4F_frameInfo_t info;
+            ret = LZ4F_getFrameInfo(dctx, &info, src, &srcSize);
+            if (LZ4F_isError(ret)) {
+                printf("LZ4F_getFrameInfo error: %s\n", LZ4F_getErrorName(ret));
+                goto cleanup;
+            }
+            /* Allocating enough space for an entire block isn't necessary for
+             * correctness, but it allows some memcpy's to be elided.
+             */
+            dstCapacity = get_block_size(&info);
+            dst = malloc(dstCapacity);
             if (!dst) { perror("decompress_file(dst)"); goto cleanup; }
-			srcPtr += srcSize;
-			srcSize = srcEnd - srcPtr;
-		}
-		/* Decompress:
-		 * Continue while there is more input to read and the frame isn't over.
-		 * If srcPtr == srcEnd then we know that there is no more output left in the
-		 * internal buffer left to flush.
-		 */
-		while (srcPtr != srcEnd && ret != 0) {
-			/* INVARIANT: Any data left in dst has already been written */
-			size_t dstSize = dstCapacity;
-			ret = LZ4F_decompress(dctx, dst, &dstSize, srcPtr, &srcSize, /* LZ4F_decompressOptions_t */ NULL);
-			if (LZ4F_isError(ret)) {
-				printf("Decompression error: %s\n", LZ4F_getErrorName(ret));
-				goto cleanup;
-			}
-			/* Flush output */
-			if (dstSize != 0){
-				size_t written = fwrite(dst, 1, dstSize, out);
-				printf("Writing %zu bytes\n", dstSize);
-				if (written != dstSize) {
-					printf("Decompress: Failed to write to file\n");
-					goto cleanup;
-				}
-			}
-			/* Update input */
-			srcPtr += srcSize;
-			srcSize = srcEnd - srcPtr;
-		}
-	}
-	/* Check that there isn't trailing input data after the frame.
-	 * It is valid to have multiple frames in the same file, but this example
-	 * doesn't support it.
-	 */
-	ret = fread(src, 1, 1, in);
-	if (ret != 0 || !feof(in)) {
-		printf("Decompress: Trailing data left in file after frame\n");
-		goto cleanup;
-	}
+            srcPtr += srcSize;
+            srcSize = srcEnd - srcPtr;
+        }
+        /* Decompress:
+         * Continue while there is more input to read and the frame isn't over.
+         * If srcPtr == srcEnd then we know that there is no more output left in the
+         * internal buffer left to flush.
+         */
+        while (srcPtr != srcEnd && ret != 0) {
+            /* INVARIANT: Any data left in dst has already been written */
+            size_t dstSize = dstCapacity;
+            ret = LZ4F_decompress(dctx, dst, &dstSize, srcPtr, &srcSize, /* LZ4F_decompressOptions_t */ NULL);
+            if (LZ4F_isError(ret)) {
+                printf("Decompression error: %s\n", LZ4F_getErrorName(ret));
+                goto cleanup;
+            }
+            /* Flush output */
+            if (dstSize != 0){
+                size_t written = fwrite(dst, 1, dstSize, out);
+                printf("Writing %zu bytes\n", dstSize);
+                if (written != dstSize) {
+                    printf("Decompress: Failed to write to file\n");
+                    goto cleanup;
+                }
+            }
+            /* Update input */
+            srcPtr += srcSize;
+            srcSize = srcEnd - srcPtr;
+        }
+    }
+    /* Check that there isn't trailing input data after the frame.
+     * It is valid to have multiple frames in the same file, but this example
+     * doesn't support it.
+     */
+    ret = fread(src, 1, 1, in);
+    if (ret != 0 || !feof(in)) {
+        printf("Decompress: Trailing data left in file after frame\n");
+        goto cleanup;
+    }
 
 cleanup:
-	free(src);
-	free(dst);
-	return LZ4F_freeDecompressionContext(dctx);   /* note : free works on NULL */
+    free(src);
+    free(dst);
+    return LZ4F_freeDecompressionContext(dctx);   /* note : free works on NULL */
 }
 
 int compare(FILE* fp0, FILE* fp1)
 {
-	int result = 0;
+    int result = 0;
 
-	while(0 == result) {
-		char b0[1024];
-		char b1[1024];
-		const size_t r0 = fread(b0, 1, sizeof(b0), fp0);
-		const size_t r1 = fread(b1, 1, sizeof(b1), fp1);
+    while(0 == result) {
+        char b0[1024];
+        char b1[1024];
+        const size_t r0 = fread(b0, 1, sizeof(b0), fp0);
+        const size_t r1 = fread(b1, 1, sizeof(b1), fp1);
 
-		result = (int) r0 - (int) r1;
+        result = (int) r0 - (int) r1;
 
-		if (0 == r0 || 0 == r1) {
-			break;
-		}
-		if (0 == result) {
-			result = memcmp(b0, b1, r0);
-		}
-	}
+        if (0 == r0 || 0 == r1) {
+            break;
+        }
+        if (0 == result) {
+            result = memcmp(b0, b1, r0);
+        }
+    }
 
-	return result;
+    return result;
 }
 
 int main(int argc, const char **argv) {
-	char inpFilename[256] = { 0 };
-	char lz4Filename[256] = { 0 };
-	char decFilename[256] = { 0 };
-
-	if(argc < 2) {
-		printf("Please specify input filename\n");
-		return 0;
-	}
-
-	snprintf(inpFilename, 256, "%s", argv[1]);
-	snprintf(lz4Filename, 256, "%s.lz4", argv[1]);
-	snprintf(decFilename, 256, "%s.lz4.dec", argv[1]);
-
-	printf("inp = [%s]\n", inpFilename);
-	printf("lz4 = [%s]\n", lz4Filename);
-	printf("dec = [%s]\n", decFilename);
-
-	/* compress */
-	{   FILE* const inpFp = fopen(inpFilename, "rb");
-		FILE* const outFp = fopen(lz4Filename, "wb");
-		size_t sizeIn = 0;
-		size_t sizeOut = 0;
-		size_t ret;
-
-		printf("compress : %s -> %s\n", inpFilename, lz4Filename);
-		ret = compress_file(inpFp, outFp, &sizeIn, &sizeOut);
-		if (ret) {
-			printf("compress : failed with code %zu\n", ret);
-			return ret;
-		}
-		printf("%s: %zu → %zu bytes, %.1f%%\n",
-			inpFilename, sizeIn, sizeOut,
-			(double)sizeOut / sizeIn * 100);
-		printf("compress : done\n");
-
-		fclose(outFp);
-		fclose(inpFp);
-	}
-
-	/* decompress */
-	{   FILE* const inpFp = fopen(lz4Filename, "rb");
-		FILE* const outFp = fopen(decFilename, "wb");
-		size_t ret;
-
-		printf("decompress : %s -> %s\n", lz4Filename, decFilename);
-		ret = decompress_file(inpFp, outFp);
-		if (ret) {
-			printf("decompress : failed with code %zu\n", ret);
-			return ret;
-		}
-		printf("decompress : done\n");
-
-		fclose(outFp);
-		fclose(inpFp);
-	}
-
-	/* verify */
-	{   FILE* const inpFp = fopen(inpFilename, "rb");
-		FILE* const decFp = fopen(decFilename, "rb");
-
-		printf("verify : %s <-> %s\n", inpFilename, decFilename);
-		const int cmp = compare(inpFp, decFp);
-		if(0 == cmp) {
-			printf("verify : OK\n");
-		} else {
-			printf("verify : NG\n");
-		}
-
-		fclose(decFp);
-		fclose(inpFp);
-	}
+    char inpFilename[256] = { 0 };
+    char lz4Filename[256] = { 0 };
+    char decFilename[256] = { 0 };
+
+    if(argc < 2) {
+        printf("Please specify input filename\n");
+        return 0;
+    }
+
+    snprintf(inpFilename, 256, "%s", argv[1]);
+    snprintf(lz4Filename, 256, "%s.lz4", argv[1]);
+    snprintf(decFilename, 256, "%s.lz4.dec", argv[1]);
+
+    printf("inp = [%s]\n", inpFilename);
+    printf("lz4 = [%s]\n", lz4Filename);
+    printf("dec = [%s]\n", decFilename);
+
+    /* compress */
+    {   FILE* const inpFp = fopen(inpFilename, "rb");
+        FILE* const outFp = fopen(lz4Filename, "wb");
+        size_t sizeIn = 0;
+        size_t sizeOut = 0;
+        size_t ret;
+
+        printf("compress : %s -> %s\n", inpFilename, lz4Filename);
+        ret = compress_file(inpFp, outFp, &sizeIn, &sizeOut);
+        if (ret) {
+            printf("compress : failed with code %zu\n", ret);
+            return ret;
+        }
+        printf("%s: %zu → %zu bytes, %.1f%%\n",
+            inpFilename, sizeIn, sizeOut,
+            (double)sizeOut / sizeIn * 100);
+        printf("compress : done\n");
+
+        fclose(outFp);
+        fclose(inpFp);
+    }
+
+    /* decompress */
+    {   FILE* const inpFp = fopen(lz4Filename, "rb");
+        FILE* const outFp = fopen(decFilename, "wb");
+        size_t ret;
+
+        printf("decompress : %s -> %s\n", lz4Filename, decFilename);
+        ret = decompress_file(inpFp, outFp);
+        if (ret) {
+            printf("decompress : failed with code %zu\n", ret);
+            return ret;
+        }
+        printf("decompress : done\n");
+
+        fclose(outFp);
+        fclose(inpFp);
+    }
+
+    /* verify */
+    {   FILE* const inpFp = fopen(inpFilename, "rb");
+        FILE* const decFp = fopen(decFilename, "rb");
+
+        printf("verify : %s <-> %s\n", inpFilename, decFilename);
+        const int cmp = compare(inpFp, decFp);
+        if(0 == cmp) {
+            printf("verify : OK\n");
+        } else {
+            printf("verify : NG\n");
+        }
+
+        fclose(decFp);
+        fclose(inpFp);
+    }
 }
-- 
cgit v0.12


From 31f2cdf4d214edcd9d4496058b0f9a4c4f8c0fad Mon Sep 17 00:00:00 2001
From: Yann Collet <cyan@fb.com>
Date: Wed, 9 Aug 2017 16:51:19 -0700
Subject: implemented dictionary compression in lz4frame

note : only compression API is implemented and tested
still to do : decompression API
---
 doc/lz4_manual.html      |   2 +-
 doc/lz4frame_manual.html |  36 ++++----
 lib/lz4.c                |   7 +-
 lib/lz4.h                |   2 +-
 lib/lz4frame.c           | 227 +++++++++++++++++++++++++++++++++--------------
 lib/lz4frame.h           |  39 ++++----
 lib/lz4frame_static.h    |  44 +++++++++
 lib/lz4hc.c              |  12 ++-
 tests/frametest.c        |  28 +++++-
 9 files changed, 285 insertions(+), 112 deletions(-)

diff --git a/doc/lz4_manual.html b/doc/lz4_manual.html
index fecd8cd..60b41a8 100644
--- a/doc/lz4_manual.html
+++ b/doc/lz4_manual.html
@@ -277,7 +277,7 @@ union LZ4_stream_u {
  init this structure before first use.
  note : only use in association with static linking !
         this definition is not API/ABI safe,
-        and may change in a future version !
+        it may change in a future version !
  
 </p></pre><BR>
 
diff --git a/doc/lz4frame_manual.html b/doc/lz4frame_manual.html
index e6873c1..dc8251e 100644
--- a/doc/lz4frame_manual.html
+++ b/doc/lz4frame_manual.html
@@ -69,13 +69,13 @@
 } LZ4F_frameType_t;
 </b></pre><BR>
 <pre><b>typedef struct {
-  LZ4F_blockSizeID_t     blockSizeID;           </b>/* max64KB, max256KB, max1MB, max4MB ; 0 == default */<b>
-  LZ4F_blockMode_t       blockMode;             </b>/* blockLinked, blockIndependent ; 0 == default */<b>
-  LZ4F_contentChecksum_t contentChecksumFlag;   </b>/* noContentChecksum, contentChecksumEnabled ; 0 == default  */<b>
-  LZ4F_frameType_t       frameType;             </b>/* LZ4F_frame, skippableFrame ; 0 == default */<b>
-  unsigned long long     contentSize;           </b>/* Size of uncompressed (original) content ; 0 == unknown */<b>
-  unsigned               dictID;                </b>/* Dictionary ID, sent by the compressor, to help the decoder select the right dictionary; 0 == no dictionary used */<b>
-  unsigned               reserved[1];           </b>/* must be zero for forward compatibility */<b>
+  LZ4F_blockSizeID_t     blockSizeID;          </b>/* max64KB, max256KB, max1MB, max4MB ; 0 == default */<b>
+  LZ4F_blockMode_t       blockMode;            </b>/* blockLinked, blockIndependent ; 0 == default */<b>
+  LZ4F_contentChecksum_t contentChecksumFlag;  </b>/* noContentChecksum, contentChecksumEnabled ; 0 == default  */<b>
+  LZ4F_frameType_t       frameType;            </b>/* LZ4F_frame, skippableFrame ; 0 == default */<b>
+  unsigned long long     contentSize;          </b>/* Size of uncompressed content ; 0 == unknown */<b>
+  unsigned               dictID;               </b>/* Dictionary ID, sent by the compressor, to help the decoder select the right dictionary; 0 == no dictionary used */<b>
+  unsigned               reserved[1];          </b>/* must be zero for forward compatibility */<b>
 } LZ4F_frameInfo_t;
 </b><p> makes it possible to supply detailed frame parameters to the stream interface.
  It's not required to set all fields, as long as the structure was initially memset() to zero.
@@ -85,7 +85,7 @@
 <pre><b>typedef struct {
   LZ4F_frameInfo_t frameInfo;
   int      compressionLevel;       </b>/* 0 == default (fast mode); values above LZ4HC_CLEVEL_MAX count as LZ4HC_CLEVEL_MAX; values below 0 trigger "fast acceleration", proportional to value */<b>
-  unsigned autoFlush;              </b>/* 1 == always flush (reduce usage of tmp buffer) */<b>
+  unsigned autoFlush;              </b>/* 1 == always flush, to reduce usage of internal buffers */<b>
   unsigned reserved[4];            </b>/* must be zero for forward compatibility */<b>
 } LZ4F_preferences_t;
 </b><p> makes it possible to supply detailed compression parameters to the stream interface.
@@ -101,12 +101,12 @@
  
 </p></pre><BR>
 
-<pre><b>size_t LZ4F_compressFrame(void* dstBuffer, size_t dstCapacity, const void* srcBuffer, size_t srcSize, const LZ4F_preferences_t* preferencesPtr);
-</b><p> Compress an entire srcBuffer into a valid LZ4 frame, as defined by specification v1.5.1
- An important rule is that dstBuffer MUST be large enough (dstCapacity) to store the result in worst case situation.
- This value is supplied by LZ4F_compressFrameBound().
- If this condition is not respected, LZ4F_compressFrame() will fail (result is an errorCode).
- The LZ4F_preferences_t structure is optional : you can provide NULL as argument. All preferences will be set to default.
+<pre><b>size_t LZ4F_compressFrame(void* dstBuffer, size_t dstCapacity,
+                                const void* srcBuffer, size_t srcSize,
+                                const LZ4F_preferences_t* preferencesPtr);
+</b><p>  Compress an entire srcBuffer into a valid LZ4 frame.
+  dstCapacity MUST be >= LZ4F_compressFrameBound(srcSize, preferencesPtr).
+  The LZ4F_preferences_t structure is optional : you can provide NULL as argument. All preferences will be set to default.
  @return : number of bytes written into dstBuffer.
            or an error code if it fails (can be tested using LZ4F_isError())
  
@@ -134,9 +134,11 @@ LZ4F_errorCode_t LZ4F_freeCompressionContext(LZ4F_cctx* cctx);
 
 <a name="Chapter8"></a><h2>Compression</h2><pre></pre>
 
-<pre><b>size_t LZ4F_compressBegin(LZ4F_cctx* cctx, void* dstBuffer, size_t dstCapacity, const LZ4F_preferences_t* prefsPtr);
-</b><p> will write the frame header into dstBuffer.
- dstCapacity must be large enough to store the header. Maximum header size is LZ4F_HEADER_SIZE_MAX bytes.
+<pre><b>size_t LZ4F_compressBegin(LZ4F_cctx* cctx,
+                                      void* dstBuffer, size_t dstCapacity,
+                                      const LZ4F_preferences_t* prefsPtr);
+</b><p>  will write the frame header into dstBuffer.
+  dstCapacity must be >= LZ4F_HEADER_SIZE_MAX bytes.
  `prefsPtr` is optional : you can provide NULL as argument, all preferences will then be set to default.
  @return : number of bytes written into dstBuffer for the header
            or an error code (which can be tested using LZ4F_isError())
diff --git a/lib/lz4.c b/lib/lz4.c
index 87ec6ab..69ee3eb 100644
--- a/lib/lz4.c
+++ b/lib/lz4.c
@@ -938,6 +938,7 @@ void LZ4_resetStream (LZ4_stream_t* LZ4_stream)
 
 int LZ4_freeStream (LZ4_stream_t* LZ4_stream)
 {
+    if (!LZ4_stream) return 0;   /* support free on NULL */
     FREEMEM(LZ4_stream);
     return (0);
 }
@@ -1277,11 +1278,6 @@ int LZ4_decompress_fast(const char* source, char* dest, int originalSize)
 
 /*===== streaming decompression functions =====*/
 
-/*
- * If you prefer dynamic allocation methods,
- * LZ4_createStreamDecode()
- * provides a pointer (void*) towards an initialized LZ4_streamDecode_t structure.
- */
 LZ4_streamDecode_t* LZ4_createStreamDecode(void)
 {
     LZ4_streamDecode_t* lz4s = (LZ4_streamDecode_t*) ALLOCATOR(1, sizeof(LZ4_streamDecode_t));
@@ -1290,6 +1286,7 @@ LZ4_streamDecode_t* LZ4_createStreamDecode(void)
 
 int LZ4_freeStreamDecode (LZ4_streamDecode_t* LZ4_stream)
 {
+    if (!LZ4_stream) return 0;   /* support free on NULL */
     FREEMEM(LZ4_stream);
     return 0;
 }
diff --git a/lib/lz4.h b/lib/lz4.h
index 5b6bc92..c5b6103 100644
--- a/lib/lz4.h
+++ b/lib/lz4.h
@@ -380,7 +380,7 @@ typedef struct {
  * init this structure before first use.
  * note : only use in association with static linking !
  *        this definition is not API/ABI safe,
- *        and may change in a future version !
+ *        it may change in a future version !
  */
 #define LZ4_STREAMSIZE_U64 ((1 << (LZ4_MEMORY_USAGE-3)) + 4)
 #define LZ4_STREAMSIZE     (LZ4_STREAMSIZE_U64 * sizeof(unsigned long long))
diff --git a/lib/lz4frame.c b/lib/lz4frame.c
index c2d6d5c..f9af991 100644
--- a/lib/lz4frame.c
+++ b/lib/lz4frame.c
@@ -170,6 +170,7 @@ typedef struct LZ4F_cctx_s
     LZ4F_preferences_t prefs;
     U32    version;
     U32    cStage;
+    int    dictionary;
     size_t maxBlockSize;
     size_t maxBufferSize;
     BYTE*  tmpBuff;
@@ -178,7 +179,7 @@ typedef struct LZ4F_cctx_s
     U64    totalInSize;
     XXH32_state_t xxh;
     void*  lz4CtxPtr;
-    U32    lz4CtxLevel;     /* 0: unallocated;  1: LZ4_stream_t;  3: LZ4_streamHC_t */
+    U32    lz4CtxLevel;   /* 0: unallocated;  1: LZ4_stream_t;  3: LZ4_streamHC_t */
 } LZ4F_cctx_t;
 
 
@@ -256,7 +257,7 @@ static LZ4F_blockSizeID_t LZ4F_optimalBSID(const LZ4F_blockSizeID_t requestedBSI
     return requestedBSID;
 }
 
-/* LZ4F_compressBound() :
+/* LZ4F_compressBound_internal() :
  * Provides dstCapacity given a srcSize to guarantee operation success in worst case situations.
  * prefsPtr is optional : if NULL is provided, preferences will be set to cover worst case scenario.
  * Result is always the same for a srcSize and prefsPtr, so it can be relied upon to size reusable buffers.
@@ -301,16 +302,19 @@ size_t LZ4F_compressFrameBound(size_t srcSize, const LZ4F_preferences_t* prefere
 }
 
 
-/*! LZ4F_compressFrame() :
- *  Compress an entire srcBuffer into a valid LZ4 frame, as defined by specification v1.5.0, in a single step.
- *  The most important rule is that dstBuffer MUST be large enough (dstCapacity) to ensure compression completion even in worst case.
- *  If this condition is not respected, LZ4F_compressFrame() will fail (result is an errorCode)
- *  Get the minimum value of dstCapacity by using LZ4F_compressFrameBound().
- *  The LZ4F_preferences_t structure is optional : if NULL is provided as argument, preferences will be set to default.
- *  The result of the function is the number of bytes written into dstBuffer.
- *  The function outputs an error code if it fails (can be tested using LZ4F_isError())
+/*! LZ4F_compressFrame_usingCDict() :
+ *  Compress srcBuffer using a dictionary, in a single step.
+ *  cdict can be NULL, in which case, no dictionary is used.
+ *  dstBuffer MUST be >= LZ4F_compressFrameBound(srcSize, preferencesPtr).
+ *  The LZ4F_preferences_t structure is optional : you may provide NULL as argument,
+ *  however, it's the only way to provide a dictID, so it's not recommended.
+ * @return : number of bytes written into dstBuffer.
+ *           or an error code if it fails (can be tested using LZ4F_isError())
  */
-size_t LZ4F_compressFrame(void* dstBuffer, size_t dstCapacity, const void* srcBuffer, size_t srcSize, const LZ4F_preferences_t* preferencesPtr)
+size_t LZ4F_compressFrame_usingCDict(void* dstBuffer, size_t dstCapacity,
+                               const void* srcBuffer, size_t srcSize,
+                               const LZ4F_CDict* cdict,
+                               const LZ4F_preferences_t* preferencesPtr)
 {
     LZ4F_cctx_t cctxI;
     LZ4_stream_t lz4ctx;
@@ -321,10 +325,12 @@ size_t LZ4F_compressFrame(void* dstBuffer, size_t dstCapacity, const void* srcBu
     BYTE* const dstEnd = dstStart + dstCapacity;
 
     memset(&cctxI, 0, sizeof(cctxI));
-    memset(&options, 0, sizeof(options));
-
     cctxI.version = LZ4F_VERSION;
-    cctxI.maxBufferSize = 5 MB;   /* mess with real buffer size to prevent dynamic allocation; works because autoflush==1 & stableSrc==1 */
+    cctxI.maxBufferSize = 5 MB;   /* mess with real buffer size to prevent dynamic allocation; works only because autoflush==1 & stableSrc==1 */
+    if (prefs.compressionLevel < LZ4HC_CLEVEL_MIN) {
+        cctxI.lz4CtxPtr = &lz4ctx;
+        cctxI.lz4CtxLevel = 1;
+    }  /* fast compression context pre-created on stack */
 
     if (preferencesPtr!=NULL)
         prefs = *preferencesPtr;
@@ -333,22 +339,18 @@ size_t LZ4F_compressFrame(void* dstBuffer, size_t dstCapacity, const void* srcBu
     if (prefs.frameInfo.contentSize != 0)
         prefs.frameInfo.contentSize = (U64)srcSize;   /* auto-correct content size if selected (!=0) */
 
-    if (prefs.compressionLevel < LZ4HC_CLEVEL_MIN) {
-        cctxI.lz4CtxPtr = &lz4ctx;
-        cctxI.lz4CtxLevel = 1;
-    }  /* otherwise : will be created within LZ4F_compressBegin */
-
     prefs.frameInfo.blockSizeID = LZ4F_optimalBSID(prefs.frameInfo.blockSizeID, srcSize);
     prefs.autoFlush = 1;
     if (srcSize <= LZ4F_getBlockSize(prefs.frameInfo.blockSizeID))
-        prefs.frameInfo.blockMode = LZ4F_blockIndependent;   /* no need for linked blocks */
+        prefs.frameInfo.blockMode = LZ4F_blockIndependent;   /* only one block => no need for inter-block link */
 
+    memset(&options, 0, sizeof(options));
     options.stableSrc = 1;
 
-    if (dstCapacity < LZ4F_compressFrameBound(srcSize, &prefs))   /* condition to guarantee success */
+    if (dstCapacity < LZ4F_compressFrameBound(srcSize, &prefs))  /* condition to guarantee success */
         return err0r(LZ4F_ERROR_dstMaxSize_tooSmall);
 
-    { size_t const headerSize = LZ4F_compressBegin(&cctxI, dstBuffer, dstCapacity, &prefs);  /* write header */
+    { size_t const headerSize = LZ4F_compressBegin_usingCDict(&cctxI, dstBuffer, dstCapacity, cdict, &prefs);  /* write header */
       if (LZ4F_isError(headerSize)) return headerSize;
       dstPtr += headerSize;   /* header size */ }
 
@@ -360,24 +362,91 @@ size_t LZ4F_compressFrame(void* dstBuffer, size_t dstCapacity, const void* srcBu
       if (LZ4F_isError(tailSize)) return tailSize;
       dstPtr += tailSize; }
 
-    if (prefs.compressionLevel >= LZ4HC_CLEVEL_MIN)   /* Ctx allocation only for lz4hc */
+    if (prefs.compressionLevel >= LZ4HC_CLEVEL_MIN)  /* Ctx allocation only for lz4hc */
         FREEMEM(cctxI.lz4CtxPtr);
 
     return (dstPtr - dstStart);
 }
 
 
+/*! LZ4F_compressFrame() :
+ *  Compress an entire srcBuffer into a valid LZ4 frame, in a single step.
+ *  dstBuffer MUST be >= LZ4F_compressFrameBound(srcSize, preferencesPtr).
+ *  The LZ4F_preferences_t structure is optional : you can provide NULL as argument. All preferences will be set to default.
+ * @return : number of bytes written into dstBuffer.
+ *           or an error code if it fails (can be tested using LZ4F_isError())
+ */
+size_t LZ4F_compressFrame(void* dstBuffer, size_t dstCapacity,
+                    const void* srcBuffer, size_t srcSize,
+                    const LZ4F_preferences_t* preferencesPtr)
+{
+    return LZ4F_compressFrame_usingCDict(dstBuffer, dstCapacity,
+                                         srcBuffer, srcSize,
+                                         NULL, preferencesPtr);
+}
+
+
+/*-***************************************************
+*   Dictionary compression
+*****************************************************/
+
+struct LZ4F_CDict_s {
+    void* dictContent;
+    LZ4_stream_t* fastCtx;
+    LZ4_streamHC_t* HCCtx;
+}; /* typedef'd to LZ4F_CDict within lz4frame_static.h */
+
+/*! LZ4_createCDict() :
+ *  When compressing multiple messages / blocks with the same dictionary, it's recommended to load it just once.
+ *  LZ4_createCDict() will create a digested dictionary, ready to start future compression operations without startup delay.
+ *  LZ4_CDict can be created once and shared by multiple threads concurrently, since its usage is read-only.
+ * `dictBuffer` can be released after LZ4_CDict creation, since its content is copied within CDict
+ * @return : digested dictionary for compression, or NULL if failed */
+LZ4F_CDict* LZ4F_createCDict(const void* dictBuffer, size_t dictSize)
+{
+    const char* dictStart = (const char*)dictBuffer;
+    LZ4F_CDict* cdict = (LZ4F_CDict*) malloc(sizeof(*cdict));
+    if (!cdict) return NULL;
+    if (dictSize > 64 KB) {
+        dictStart += dictSize - 64 KB;
+        dictSize = 64 KB;
+    }
+    cdict->dictContent = ALLOCATOR(dictSize);
+    cdict->fastCtx = LZ4_createStream();
+    cdict->HCCtx = LZ4_createStreamHC();
+    if (!cdict->dictContent || !cdict->fastCtx || !cdict->HCCtx) {
+        LZ4F_freeCDict(cdict);
+        return NULL;
+    }
+    memcpy(cdict->dictContent, dictStart, dictSize);
+    LZ4_resetStream(cdict->fastCtx);
+    LZ4_loadDict (cdict->fastCtx, cdict->dictContent, (int)dictSize);
+    LZ4_resetStreamHC(cdict->HCCtx, LZ4HC_CLEVEL_DEFAULT);
+    LZ4_loadDictHC(cdict->HCCtx, cdict->dictContent, (int)dictSize);
+    return cdict;
+}
+
+void LZ4F_freeCDict(LZ4F_CDict* cdict)
+{
+    if (cdict==NULL) return;  /* support free on NULL */
+    FREEMEM(cdict->dictContent);
+    LZ4_freeStream(cdict->fastCtx);
+    LZ4_freeStreamHC(cdict->HCCtx);
+    FREEMEM(cdict);
+}
+
+
 /*-*********************************
 *  Advanced compression functions
 ***********************************/
 
 /*! LZ4F_createCompressionContext() :
- * The first thing to do is to create a compressionContext object, which will be used in all compression operations.
- * This is achieved using LZ4F_createCompressionContext(), which takes as argument a version and an LZ4F_preferences_t structure.
- * The version provided MUST be LZ4F_VERSION. It is intended to track potential version differences between different binaries.
- * The function will provide a pointer to an allocated LZ4F_compressionContext_t object.
- * If the result LZ4F_errorCode_t is not OK_NoError, there was an error during context creation.
- * Object can release its memory using LZ4F_freeCompressionContext();
+ *  The first thing to do is to create a compressionContext object, which will be used in all compression operations.
+ *  This is achieved using LZ4F_createCompressionContext(), which takes as argument a version and an LZ4F_preferences_t structure.
+ *  The version provided MUST be LZ4F_VERSION. It is intended to track potential incompatible differences between different binaries.
+ *  The function will provide a pointer to an allocated LZ4F_compressionContext_t object.
+ *  If the result LZ4F_errorCode_t is not OK_NoError, there was an error during context creation.
+ *  Object can release its memory using LZ4F_freeCompressionContext();
  */
 LZ4F_errorCode_t LZ4F_createCompressionContext(LZ4F_compressionContext_t* LZ4F_compressionContextPtr, unsigned version)
 {
@@ -385,7 +454,7 @@ LZ4F_errorCode_t LZ4F_createCompressionContext(LZ4F_compressionContext_t* LZ4F_c
     if (cctxPtr==NULL) return err0r(LZ4F_ERROR_allocation_failed);
 
     cctxPtr->version = version;
-    cctxPtr->cStage = 0;   /* Next stage : write header */
+    cctxPtr->cStage = 0;   /* Next stage : init stream */
 
     *LZ4F_compressionContextPtr = (LZ4F_compressionContext_t)cctxPtr;
 
@@ -397,8 +466,8 @@ LZ4F_errorCode_t LZ4F_freeCompressionContext(LZ4F_compressionContext_t LZ4F_comp
 {
     LZ4F_cctx_t* const cctxPtr = (LZ4F_cctx_t*)LZ4F_compressionContext;
 
-    if (cctxPtr != NULL) {  /* null pointers can be safely provided to this function, like free() */
-       FREEMEM(cctxPtr->lz4CtxPtr);
+    if (cctxPtr != NULL) {  /* support free on NULL */
+       FREEMEM(cctxPtr->lz4CtxPtr);  /* works because LZ4_streamHC_t and LZ4_stream_t are simple POD types */
        FREEMEM(cctxPtr->tmpBuff);
        FREEMEM(LZ4F_compressionContext);
     }
@@ -407,22 +476,23 @@ LZ4F_errorCode_t LZ4F_freeCompressionContext(LZ4F_compressionContext_t LZ4F_comp
 }
 
 
-/*! LZ4F_compressBegin() :
- *  will write the frame header into dstBuffer.
- *  dstBuffer must be large enough to accommodate a header (dstCapacity). Maximum header size is LZ4F_HEADER_SIZE_MAX bytes.
- *  @return : number of bytes written into dstBuffer for the header
- *            or an error code (can be tested using LZ4F_isError())
+/*! LZ4F_compressBegin_usingCDict() :
+ *  init streaming compression and writes frame header into dstBuffer.
+ *  dstBuffer must be >= LZ4F_HEADER_SIZE_MAX bytes.
+ * @return : number of bytes written into dstBuffer for the header
+ *           or an error code (can be tested using LZ4F_isError())
  */
-size_t LZ4F_compressBegin(LZ4F_cctx* cctxPtr, void* dstBuffer, size_t dstCapacity, const LZ4F_preferences_t* preferencesPtr)
+size_t LZ4F_compressBegin_usingCDict(LZ4F_cctx* cctxPtr,
+                          void* dstBuffer, size_t dstCapacity,
+                          const LZ4F_CDict* cdict,
+                          const LZ4F_preferences_t* preferencesPtr)
 {
     LZ4F_preferences_t prefNull;
     BYTE* const dstStart = (BYTE*)dstBuffer;
     BYTE* dstPtr = dstStart;
     BYTE* headerStart;
-    size_t requiredBuffSize;
 
     if (dstCapacity < maxFHSize) return err0r(LZ4F_ERROR_dstMaxSize_tooSmall);
-    if (cctxPtr->cStage != 0) return err0r(LZ4F_ERROR_GENERIC);
     memset(&prefNull, 0, sizeof(prefNull));
     if (preferencesPtr == NULL) preferencesPtr = &prefNull;
     cctxPtr->prefs = *preferencesPtr;
@@ -437,31 +507,41 @@ size_t LZ4F_compressBegin(LZ4F_cctx* cctxPtr, void* dstBuffer, size_t dstCapacit
                 cctxPtr->lz4CtxPtr = (void*)LZ4_createStreamHC();
             if (cctxPtr->lz4CtxPtr == NULL) return err0r(LZ4F_ERROR_allocation_failed);
             cctxPtr->lz4CtxLevel = tableID;
-        }
-    }
+    }   }
 
     /* Buffer Management */
-    if (cctxPtr->prefs.frameInfo.blockSizeID == 0) cctxPtr->prefs.frameInfo.blockSizeID = LZ4F_BLOCKSIZEID_DEFAULT;
+    if (cctxPtr->prefs.frameInfo.blockSizeID == 0)
+        cctxPtr->prefs.frameInfo.blockSizeID = LZ4F_BLOCKSIZEID_DEFAULT;
     cctxPtr->maxBlockSize = LZ4F_getBlockSize(cctxPtr->prefs.frameInfo.blockSizeID);
 
-    requiredBuffSize = cctxPtr->maxBlockSize + ((cctxPtr->prefs.frameInfo.blockMode == LZ4F_blockLinked) * 128 KB);
-    if (preferencesPtr->autoFlush)
-        requiredBuffSize = (cctxPtr->prefs.frameInfo.blockMode == LZ4F_blockLinked) * 64 KB;   /* just needs dict */
+    {   size_t const requiredBuffSize = preferencesPtr->autoFlush ?
+                (cctxPtr->prefs.frameInfo.blockMode == LZ4F_blockLinked) * 64 KB :  /* only needs windows size */
+                cctxPtr->maxBlockSize + ((cctxPtr->prefs.frameInfo.blockMode == LZ4F_blockLinked) * 128 KB);
 
-    if (cctxPtr->maxBufferSize < requiredBuffSize) {
-        cctxPtr->maxBufferSize = 0;
-        FREEMEM(cctxPtr->tmpBuff);
-        cctxPtr->tmpBuff = (BYTE*)ALLOCATOR(requiredBuffSize);
-        if (cctxPtr->tmpBuff == NULL) return err0r(LZ4F_ERROR_allocation_failed);
-        cctxPtr->maxBufferSize = requiredBuffSize;
-    }
+        if (cctxPtr->maxBufferSize < requiredBuffSize) {
+            cctxPtr->maxBufferSize = 0;
+            FREEMEM(cctxPtr->tmpBuff);
+            cctxPtr->tmpBuff = (BYTE*)ALLOCATOR(requiredBuffSize);
+            if (cctxPtr->tmpBuff == NULL) return err0r(LZ4F_ERROR_allocation_failed);
+            cctxPtr->maxBufferSize = requiredBuffSize;
+    }   }
     cctxPtr->tmpIn = cctxPtr->tmpBuff;
     cctxPtr->tmpInSize = 0;
     XXH32_reset(&(cctxPtr->xxh), 0);
-    if (cctxPtr->prefs.compressionLevel < LZ4HC_CLEVEL_MIN)
-        LZ4_resetStream((LZ4_stream_t*)(cctxPtr->lz4CtxPtr));
-    else
-        LZ4_resetStreamHC((LZ4_streamHC_t*)(cctxPtr->lz4CtxPtr), cctxPtr->prefs.compressionLevel);
+
+    /* context init */
+    cctxPtr->dictionary = (cdict!=NULL);
+    if (cdict) {
+        if (cctxPtr->prefs.compressionLevel < LZ4HC_CLEVEL_MIN) {
+            memcpy(cctxPtr->lz4CtxPtr, cdict->fastCtx, sizeof(*cdict->fastCtx));
+        } else
+            memcpy(cctxPtr->lz4CtxPtr, cdict->HCCtx, sizeof(*cdict->HCCtx));
+    } else {
+        if (cctxPtr->prefs.compressionLevel < LZ4HC_CLEVEL_MIN)
+            LZ4_resetStream((LZ4_stream_t*)(cctxPtr->lz4CtxPtr));
+        else
+            LZ4_resetStreamHC((LZ4_streamHC_t*)(cctxPtr->lz4CtxPtr), cctxPtr->prefs.compressionLevel);
+    }
 
     /* Magic Number */
     LZ4F_writeLE32(dstPtr, LZ4F_MAGICNUMBER);
@@ -487,16 +567,31 @@ size_t LZ4F_compressBegin(LZ4F_cctx* cctxPtr, void* dstBuffer, size_t dstCapacit
         LZ4F_writeLE32(dstPtr, cctxPtr->prefs.frameInfo.dictID);
         dstPtr += 4;
     }
-    /* CRC Byte */
+    /* Header CRC Byte */
     *dstPtr = LZ4F_headerChecksum(headerStart, dstPtr - headerStart);
     dstPtr++;
 
     cctxPtr->cStage = 1;   /* header written, now request input data block */
-
     return (dstPtr - dstStart);
 }
 
 
+/*! LZ4F_compressBegin() :
+ *  init streaming compression and writes frame header into dstBuffer.
+ *  dstBuffer must be >= LZ4F_HEADER_SIZE_MAX bytes.
+ *  preferencesPtr can be NULL, in which case default parameters are selected.
+ * @return : number of bytes written into dstBuffer for the header
+ *           or an error code (can be tested using LZ4F_isError())
+ */
+size_t LZ4F_compressBegin(LZ4F_cctx* cctxPtr,
+                          void* dstBuffer, size_t dstCapacity,
+                          const LZ4F_preferences_t* preferencesPtr)
+{
+    return LZ4F_compressBegin_usingCDict(cctxPtr, dstBuffer, dstCapacity,
+                                         NULL, preferencesPtr);
+}
+
+
 /* LZ4F_compressBound() :
  *      @ return size of Dst buffer given a srcSize to handle worst case situations.
  *      The LZ4F_frameInfo_t structure is optional : if NULL, preferences will be set to cover worst case situations.
@@ -537,19 +632,19 @@ static int LZ4F_localLZ4_compress_limitedOutput_continue(void* ctx, const char*
     return LZ4_compress_fast_continue((LZ4_stream_t*)ctx, src, dst, srcSize, dstCapacity, acceleration);
 }
 
-static int LZ4F_localLZ4_compressHC_limitedOutput_continue(void* ctx, const char* src, char* dst, int srcSize, int dstSize, int level)
+static int LZ4F_localLZ4_compressHC_limitedOutput_continue(void* ctx, const char* src, char* dst, int srcSize, int dstCapacity, int level)
 {
     (void) level;
-    return LZ4_compress_HC_continue((LZ4_streamHC_t*)ctx, src, dst, srcSize, dstSize);
+    return LZ4_compress_HC_continue((LZ4_streamHC_t*)ctx, src, dst, srcSize, dstCapacity);
 }
 
-static compressFunc_t LZ4F_selectCompression(LZ4F_blockMode_t blockMode, int level)
+static compressFunc_t LZ4F_selectCompression(LZ4F_blockMode_t blockMode, int dictionary, int level)
 {
     if (level < LZ4HC_CLEVEL_MIN) {
-        if (blockMode == LZ4F_blockIndependent) return LZ4F_localLZ4_compress_limitedOutput_withState;
+        if (blockMode == LZ4F_blockIndependent && !dictionary) return LZ4F_localLZ4_compress_limitedOutput_withState;
         return LZ4F_localLZ4_compress_limitedOutput_continue;
     }
-    if (blockMode == LZ4F_blockIndependent) return LZ4_compress_HC_extStateHC;
+    if (blockMode == LZ4F_blockIndependent && !dictionary) return LZ4_compress_HC_extStateHC;
     return LZ4F_localLZ4_compressHC_limitedOutput_continue;
 }
 
@@ -580,7 +675,7 @@ size_t LZ4F_compressUpdate(LZ4F_cctx* cctxPtr, void* dstBuffer, size_t dstCapaci
     BYTE* const dstStart = (BYTE*)dstBuffer;
     BYTE* dstPtr = dstStart;
     LZ4F_lastBlockStatus lastBlockCompressed = notDone;
-    compressFunc_t const compress = LZ4F_selectCompression(cctxPtr->prefs.frameInfo.blockMode, cctxPtr->prefs.compressionLevel);
+    compressFunc_t const compress = LZ4F_selectCompression(cctxPtr->prefs.frameInfo.blockMode, cctxPtr->dictionary, cctxPtr->prefs.compressionLevel);
 
 
     if (cctxPtr->cStage != 1) return err0r(LZ4F_ERROR_GENERIC);
@@ -679,7 +774,7 @@ size_t LZ4F_flush(LZ4F_cctx* cctxPtr, void* dstBuffer, size_t dstCapacity, const
     (void)compressOptionsPtr;   /* not yet useful */
 
     /* select compression function */
-    compress = LZ4F_selectCompression(cctxPtr->prefs.frameInfo.blockMode, cctxPtr->prefs.compressionLevel);
+    compress = LZ4F_selectCompression(cctxPtr->prefs.frameInfo.blockMode, cctxPtr->dictionary, cctxPtr->prefs.compressionLevel);
 
     /* compress tmp buffer */
     dstPtr += LZ4F_compressBlock(dstPtr, cctxPtr->tmpIn, cctxPtr->tmpInSize, compress, cctxPtr->lz4CtxPtr, cctxPtr->prefs.compressionLevel);
diff --git a/lib/lz4frame.h b/lib/lz4frame.h
index 0efe220..42e2f53 100644
--- a/lib/lz4frame.h
+++ b/lib/lz4frame.h
@@ -157,13 +157,13 @@ typedef LZ4F_contentChecksum_t contentChecksum_t;
  * It's not required to set all fields, as long as the structure was initially memset() to zero.
  * All reserved fields must be set to zero. */
 typedef struct {
-  LZ4F_blockSizeID_t     blockSizeID;           /* max64KB, max256KB, max1MB, max4MB ; 0 == default */
-  LZ4F_blockMode_t       blockMode;             /* blockLinked, blockIndependent ; 0 == default */
-  LZ4F_contentChecksum_t contentChecksumFlag;   /* noContentChecksum, contentChecksumEnabled ; 0 == default  */
-  LZ4F_frameType_t       frameType;             /* LZ4F_frame, skippableFrame ; 0 == default */
-  unsigned long long     contentSize;           /* Size of uncompressed (original) content ; 0 == unknown */
-  unsigned               dictID;                /* Dictionary ID, sent by the compressor, to help the decoder select the right dictionary; 0 == no dictionary used */
-  unsigned               reserved[1];           /* must be zero for forward compatibility */
+  LZ4F_blockSizeID_t     blockSizeID;          /* max64KB, max256KB, max1MB, max4MB ; 0 == default */
+  LZ4F_blockMode_t       blockMode;            /* blockLinked, blockIndependent ; 0 == default */
+  LZ4F_contentChecksum_t contentChecksumFlag;  /* noContentChecksum, contentChecksumEnabled ; 0 == default  */
+  LZ4F_frameType_t       frameType;            /* LZ4F_frame, skippableFrame ; 0 == default */
+  unsigned long long     contentSize;          /* Size of uncompressed content ; 0 == unknown */
+  unsigned               dictID;               /* Dictionary ID, sent by the compressor, to help the decoder select the right dictionary; 0 == no dictionary used */
+  unsigned               reserved[1];          /* must be zero for forward compatibility */
 } LZ4F_frameInfo_t;
 
 /*! LZ4F_preferences_t :
@@ -173,7 +173,7 @@ typedef struct {
 typedef struct {
   LZ4F_frameInfo_t frameInfo;
   int      compressionLevel;       /* 0 == default (fast mode); values above LZ4HC_CLEVEL_MAX count as LZ4HC_CLEVEL_MAX; values below 0 trigger "fast acceleration", proportional to value */
-  unsigned autoFlush;              /* 1 == always flush (reduce usage of tmp buffer) */
+  unsigned autoFlush;              /* 1 == always flush, to reduce usage of internal buffers */
   unsigned reserved[4];            /* must be zero for forward compatibility */
 } LZ4F_preferences_t;
 
@@ -187,17 +187,16 @@ typedef struct {
  */
 LZ4FLIB_API size_t LZ4F_compressFrameBound(size_t srcSize, const LZ4F_preferences_t* preferencesPtr);
 
-/*!LZ4F_compressFrame() :
- * Compress an entire srcBuffer into a valid LZ4 frame, as defined by specification v1.5.1
- * An important rule is that dstBuffer MUST be large enough (dstCapacity) to store the result in worst case situation.
- * This value is supplied by LZ4F_compressFrameBound().
- * If this condition is not respected, LZ4F_compressFrame() will fail (result is an errorCode).
- * The LZ4F_preferences_t structure is optional : you can provide NULL as argument. All preferences will be set to default.
+/*! LZ4F_compressFrame() :
+ *  Compress an entire srcBuffer into a valid LZ4 frame.
+ *  dstCapacity MUST be >= LZ4F_compressFrameBound(srcSize, preferencesPtr).
+ *  The LZ4F_preferences_t structure is optional : you can provide NULL as argument. All preferences will be set to default.
  * @return : number of bytes written into dstBuffer.
  *           or an error code if it fails (can be tested using LZ4F_isError())
  */
-LZ4FLIB_API size_t LZ4F_compressFrame(void* dstBuffer, size_t dstCapacity, const void* srcBuffer, size_t srcSize, const LZ4F_preferences_t* preferencesPtr);
-
+LZ4FLIB_API size_t LZ4F_compressFrame(void* dstBuffer, size_t dstCapacity,
+                                const void* srcBuffer, size_t srcSize,
+                                const LZ4F_preferences_t* preferencesPtr);
 
 
 /*-***********************************
@@ -231,13 +230,15 @@ LZ4FLIB_API LZ4F_errorCode_t LZ4F_freeCompressionContext(LZ4F_cctx* cctx);
 
 #define LZ4F_HEADER_SIZE_MAX 19
 /*! LZ4F_compressBegin() :
- * will write the frame header into dstBuffer.
- * dstCapacity must be large enough to store the header. Maximum header size is LZ4F_HEADER_SIZE_MAX bytes.
+ *  will write the frame header into dstBuffer.
+ *  dstCapacity must be >= LZ4F_HEADER_SIZE_MAX bytes.
  * `prefsPtr` is optional : you can provide NULL as argument, all preferences will then be set to default.
  * @return : number of bytes written into dstBuffer for the header
  *           or an error code (which can be tested using LZ4F_isError())
  */
-LZ4FLIB_API size_t LZ4F_compressBegin(LZ4F_cctx* cctx, void* dstBuffer, size_t dstCapacity, const LZ4F_preferences_t* prefsPtr);
+LZ4FLIB_API size_t LZ4F_compressBegin(LZ4F_cctx* cctx,
+                                      void* dstBuffer, size_t dstCapacity,
+                                      const LZ4F_preferences_t* prefsPtr);
 
 /*! LZ4F_compressBound() :
  * Provides dstCapacity given a srcSize to guarantee operation success in worst case situations.
diff --git a/lib/lz4frame_static.h b/lib/lz4frame_static.h
index d3bae82..5f22aed 100644
--- a/lib/lz4frame_static.h
+++ b/lib/lz4frame_static.h
@@ -82,6 +82,50 @@ typedef enum { LZ4F_LIST_ERRORS(LZ4F_GENERATE_ENUM) } LZ4F_errorCodes;
 LZ4F_errorCodes LZ4F_getErrorCode(size_t functionResult);
 
 
+
+/**********************************
+ *  Bulk processing dictionary API
+ *********************************/
+typedef struct LZ4F_CDict_s LZ4F_CDict;
+
+/*! LZ4_createCDict() :
+ *  When compressing multiple messages / blocks with the same dictionary, it's recommended to load it just once.
+ *  LZ4_createCDict() will create a digested dictionary, ready to start future compression operations without startup delay.
+ *  LZ4_CDict can be created once and shared by multiple threads concurrently, since its usage is read-only.
+ *  `dictBuffer` can be released after LZ4_CDict creation, since its content is copied within CDict */
+LZ4F_CDict* LZ4F_createCDict(const void* dictBuffer, size_t dictSize);
+void        LZ4F_freeCDict(LZ4F_CDict* CDict);
+
+/*! LZ4_compressFrame_usingCDict() :
+ *  Compress an entire srcBuffer into a valid LZ4 frame using a digested Dictionary.
+ *  If cdict==NULL, compress without a dictionary.
+ *  dstBuffer MUST be >= LZ4F_compressFrameBound(srcSize, preferencesPtr).
+ *  If this condition is not respected, function will fail (@return an errorCode).
+ *  The LZ4F_preferences_t structure is optional : you may provide NULL as argument,
+ *  but it's not recommended, as it's the only way to provide dictID in the frame header.
+ * @return : number of bytes written into dstBuffer.
+ *           or an error code if it fails (can be tested using LZ4F_isError())
+ */
+size_t LZ4F_compressFrame_usingCDict(void* dst, size_t dstCapacity,
+                               const void* src, size_t srcSize,
+                               const LZ4F_CDict* cdict,
+                               const LZ4F_preferences_t* preferencesPtr);
+
+
+/*! LZ4F_compressBegin_usingCDict() :
+ *  Inits streaming dictionary compression, and writes the frame header into dstBuffer.
+ *  dstCapacity must be >= LZ4F_HEADER_SIZE_MAX bytes.
+ * `prefsPtr` is optional : you may provide NULL as argument,
+ *  however, it's the only way to provide dictID in the frame header.
+ * @return : number of bytes written into dstBuffer for the header,
+ *           or an error code (which can be tested using LZ4F_isError())
+ */
+size_t LZ4F_compressBegin_usingCDict(LZ4F_cctx* cctx,
+                                     void* dstBuffer, size_t dstCapacity,
+                                     const LZ4F_CDict* cdict,
+                                     const LZ4F_preferences_t* prefsPtr);
+
+
 #if defined (__cplusplus)
 }
 #endif
diff --git a/lib/lz4hc.c b/lib/lz4hc.c
index ca9c2e6..b17760d 100644
--- a/lib/lz4hc.c
+++ b/lib/lz4hc.c
@@ -610,7 +610,11 @@ int LZ4_compress_HC_destSize(void* LZ4HC_Data, const char* source, char* dest, i
 **************************************/
 /* allocation */
 LZ4_streamHC_t* LZ4_createStreamHC(void) { return (LZ4_streamHC_t*)malloc(sizeof(LZ4_streamHC_t)); }
-int             LZ4_freeStreamHC (LZ4_streamHC_t* LZ4_streamHCPtr) { free(LZ4_streamHCPtr); return 0; }
+int             LZ4_freeStreamHC (LZ4_streamHC_t* LZ4_streamHCPtr) {
+    if (!LZ4_streamHCPtr) return 0;  /* support free on NULL */
+    free(LZ4_streamHCPtr);
+    return 0;
+}
 
 
 /* initialization */
@@ -767,7 +771,11 @@ void* LZ4_createHC (char* inputBuffer)
     return hc4;
 }
 
-int LZ4_freeHC (void* LZ4HC_Data) { FREEMEM(LZ4HC_Data); return 0; }
+int LZ4_freeHC (void* LZ4HC_Data) {
+    if (!LZ4HC_Data) return 0;  /* support free on NULL */
+    FREEMEM(LZ4HC_Data);
+    return 0;
+}
 
 int LZ4_compressHC2_continue (void* LZ4HC_Data, const char* src, char* dst, int srcSize, int cLevel)
 {
diff --git a/tests/frametest.c b/tests/frametest.c
index 02d7e5b..1ee0d96 100644
--- a/tests/frametest.c
+++ b/tests/frametest.c
@@ -482,10 +482,36 @@ int basicTests(U32 seed, double compressibility)
         if (prefs.frameInfo.dictID != dictID) goto _output_error;
         DISPLAYLEVEL(3, "%u \n", (U32)prefs.frameInfo.dictID);
 
-        CHECK( LZ4F_freeCompressionContext(cctx) ); cctx = NULL;
         CHECK( LZ4F_freeDecompressionContext(dCtx) ); dCtx = NULL;
+        CHECK( LZ4F_freeCompressionContext(cctx) ); cctx = NULL;
+    }
+
+
+    /* Dictionary compression test */
+    {   size_t const dictSize = 63 KB;
+        size_t const dstCapacity = LZ4F_compressFrameBound(dictSize, NULL);
+        size_t cSizeNoDict, cSizeWithDict;
+        LZ4F_CDict* const cdict = LZ4F_createCDict(CNBuffer, dictSize);
+        if (cdict == NULL) goto _output_error;
+        DISPLAYLEVEL(3, "LZ4F_compressFrame_usingCDict, with NULL dict : ");
+        CHECK_V(cSizeNoDict,
+                LZ4F_compressFrame_usingCDict(compressedBuffer, dstCapacity,
+                                              CNBuffer, dictSize,
+                                              NULL, NULL) );
+        DISPLAYLEVEL(3, "%u bytes \n", (unsigned)cSizeNoDict);
+
+        DISPLAYLEVEL(3, "LZ4F_compressFrame_usingCDict, with dict : ");
+        CHECK_V(cSizeWithDict,
+                LZ4F_compressFrame_usingCDict(compressedBuffer, dstCapacity,
+                                              CNBuffer, dictSize,
+                                              cdict, NULL) );
+        DISPLAYLEVEL(3, "%u bytes \n", (unsigned)cSizeWithDict);
+        if (cSizeWithDict >= cSizeNoDict) goto _output_error;  /* must be more efficient */
+
+        LZ4F_freeCDict(cdict);
     }
 
+
     DISPLAYLEVEL(3, "Skippable frame test : \n");
     {   size_t decodedBufferSize = COMPRESSIBLE_NOISE_LENGTH;
         unsigned maxBits = FUZ_highbit((U32)decodedBufferSize);
-- 
cgit v0.12


From bf8daa2fd52fe4a87b59f74e3f3c249f57218391 Mon Sep 17 00:00:00 2001
From: Yann Collet <cyan@fb.com>
Date: Wed, 9 Aug 2017 18:00:48 -0700
Subject: fixed uninitialization error in lz4frame

---
 lib/lz4frame.c | 9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/lib/lz4frame.c b/lib/lz4frame.c
index f9af991..07cbf56 100644
--- a/lib/lz4frame.c
+++ b/lib/lz4frame.c
@@ -327,10 +327,6 @@ size_t LZ4F_compressFrame_usingCDict(void* dstBuffer, size_t dstCapacity,
     memset(&cctxI, 0, sizeof(cctxI));
     cctxI.version = LZ4F_VERSION;
     cctxI.maxBufferSize = 5 MB;   /* mess with real buffer size to prevent dynamic allocation; works only because autoflush==1 & stableSrc==1 */
-    if (prefs.compressionLevel < LZ4HC_CLEVEL_MIN) {
-        cctxI.lz4CtxPtr = &lz4ctx;
-        cctxI.lz4CtxLevel = 1;
-    }  /* fast compression context pre-created on stack */
 
     if (preferencesPtr!=NULL)
         prefs = *preferencesPtr;
@@ -344,6 +340,11 @@ size_t LZ4F_compressFrame_usingCDict(void* dstBuffer, size_t dstCapacity,
     if (srcSize <= LZ4F_getBlockSize(prefs.frameInfo.blockSizeID))
         prefs.frameInfo.blockMode = LZ4F_blockIndependent;   /* only one block => no need for inter-block link */
 
+    if (prefs.compressionLevel < LZ4HC_CLEVEL_MIN) {
+        cctxI.lz4CtxPtr = &lz4ctx;
+        cctxI.lz4CtxLevel = 1;
+    }  /* fast compression context pre-created on stack */
+
     memset(&options, 0, sizeof(options));
     options.stableSrc = 1;
 
-- 
cgit v0.12


From ca2fb166ab650835c71099842b646d388cebb3ac Mon Sep 17 00:00:00 2001
From: Yann Collet <cyan@fb.com>
Date: Wed, 9 Aug 2017 18:22:26 -0700
Subject: fixed C++ conversion warnings

---
 lib/lz4frame.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/lib/lz4frame.c b/lib/lz4frame.c
index 07cbf56..180658d 100644
--- a/lib/lz4frame.c
+++ b/lib/lz4frame.c
@@ -421,9 +421,9 @@ LZ4F_CDict* LZ4F_createCDict(const void* dictBuffer, size_t dictSize)
     }
     memcpy(cdict->dictContent, dictStart, dictSize);
     LZ4_resetStream(cdict->fastCtx);
-    LZ4_loadDict (cdict->fastCtx, cdict->dictContent, (int)dictSize);
+    LZ4_loadDict (cdict->fastCtx, (const char*)cdict->dictContent, (int)dictSize);
     LZ4_resetStreamHC(cdict->HCCtx, LZ4HC_CLEVEL_DEFAULT);
-    LZ4_loadDictHC(cdict->HCCtx, cdict->dictContent, (int)dictSize);
+    LZ4_loadDictHC(cdict->HCCtx, (const char*)cdict->dictContent, (int)dictSize);
     return cdict;
 }
 
-- 
cgit v0.12


From d8aafe2c52b4b16da9e8d289ad9bdb04b0bc4a05 Mon Sep 17 00:00:00 2001
From: Yann Collet <cyan@fb.com>
Date: Thu, 10 Aug 2017 00:48:19 -0700
Subject: dictionary compression correctly uses compression level

Not obvious : copying the state was copying cdict's compression level
---
 doc/lz4_manual.html      | 36 ++++++++++++++++++++----------------
 doc/lz4frame_manual.html |  2 +-
 lib/lz4.h                | 36 ++++++++++++++++++------------------
 lib/lz4frame.c           | 23 +++++++++++++----------
 lib/lz4frame.h           |  4 +++-
 lib/lz4hc.c              | 12 ++++++++++++
 lib/lz4hc.h              | 23 ++++++++++++++++-------
 tests/frametest.c        | 24 ++++++++++++++++++++++++
 8 files changed, 107 insertions(+), 53 deletions(-)

diff --git a/doc/lz4_manual.html b/doc/lz4_manual.html
index 60b41a8..ecc985d 100644
--- a/doc/lz4_manual.html
+++ b/doc/lz4_manual.html
@@ -175,8 +175,8 @@ int           LZ4_freeStream (LZ4_stream_t* streamPtr);
   Important : Previous data blocks are assumed to remain present and unmodified !
   'dst' buffer must be already allocated.
   If dstCapacity >= LZ4_compressBound(srcSize), compression is guaranteed to succeed, and runs faster.
-  If not, and if compressed data cannot fit into 'dst' buffer size, compression stops, and function returns a zero.
-  After an error, the stream status is invalid, and it can only be reset or freed.
+  If not, and if compressed data cannot fit into 'dst' buffer size, compression stops, and function @return==0.
+  After an error, the stream status is invalid, it can only be reset or freed.
  
 </p></pre><BR>
 
@@ -205,20 +205,20 @@ int                 LZ4_freeStreamDecode (LZ4_streamDecode_t* LZ4_stream);
 
 <pre><b>int LZ4_decompress_safe_continue (LZ4_streamDecode_t* LZ4_streamDecode, const char* source, char* dest, int compressedSize, int maxDecompressedSize);
 int LZ4_decompress_fast_continue (LZ4_streamDecode_t* LZ4_streamDecode, const char* source, char* dest, int originalSize);
-</b><p>    These decoding functions allow decompression of multiple blocks in "streaming" mode.
-    Previously decoded blocks *must* remain available at the memory position where they were decoded (up to 64 KB)
-    In the case of a ring buffers, decoding buffer must be either :
-    - Exactly same size as encoding buffer, with same update rule (block boundaries at same positions)
-      In which case, the decoding & encoding ring buffer can have any size, including very small ones ( < 64 KB).
-    - Larger than encoding buffer, by a minimum of maxBlockSize more bytes.
-      maxBlockSize is implementation dependent. It's the maximum size you intend to compress into a single block.
-      In which case, encoding and decoding buffers do not need to be synchronized,
-      and encoding ring buffer can have any size, including small ones ( < 64 KB).
-    - _At least_ 64 KB + 8 bytes + maxBlockSize.
-      In which case, encoding and decoding buffers do not need to be synchronized,
-      and encoding ring buffer can have any size, including larger than decoding buffer.
-    Whenever these conditions are not possible, save the last 64KB of decoded data into a safe buffer,
-    and indicate where it is saved using LZ4_setStreamDecode()
+</b><p>  These decoding functions allow decompression of multiple blocks in "streaming" mode.
+  Previously decoded blocks *must* remain available at the memory position where they were decoded (up to 64 KB)
+  In the case of a ring buffers, decoding buffer must be either :
+  - Exactly same size as encoding buffer, with same update rule (block boundaries at same positions)
+    In which case, the decoding & encoding ring buffer can have any size, including very small ones ( < 64 KB).
+  - Larger than encoding buffer, by a minimum of maxBlockSize more bytes.
+    maxBlockSize is implementation dependent. It's the maximum size you intend to compress into a single block.
+    In which case, encoding and decoding buffers do not need to be synchronized,
+    and encoding ring buffer can have any size, including small ones ( < 64 KB).
+  - _At least_ 64 KB + 8 bytes + maxBlockSize.
+    In which case, encoding and decoding buffers do not need to be synchronized,
+    and encoding ring buffer can have any size, including larger than decoding buffer.
+  Whenever these conditions are not possible, save the last 64KB of decoded data into a safe buffer,
+  and indicate where it is saved using LZ4_setStreamDecode()
 </p></pre><BR>
 
 <pre><b>int LZ4_decompress_safe_usingDict (const char* source, char* dest, int compressedSize, int maxDecompressedSize, const char* dictStart, int dictSize);
@@ -321,5 +321,9 @@ union LZ4_streamDecode_u {
    Otherwise, it's also possible to define LZ4_DISABLE_DEPRECATE_WARNINGS 
 </p></pre><BR>
 
+<h3>Experimental API section</h3><pre></pre><b><pre>#ifdef LZ4_HC_STATIC_LINKING_ONLY
+#ifndef LZ4_SLO_299387928743
+#define LZ4_SLO_299387928743
+</pre></b><BR>
 </html>
 </body>
diff --git a/doc/lz4frame_manual.html b/doc/lz4frame_manual.html
index dc8251e..a1a6e96 100644
--- a/doc/lz4frame_manual.html
+++ b/doc/lz4frame_manual.html
@@ -74,7 +74,7 @@
   LZ4F_contentChecksum_t contentChecksumFlag;  </b>/* noContentChecksum, contentChecksumEnabled ; 0 == default  */<b>
   LZ4F_frameType_t       frameType;            </b>/* LZ4F_frame, skippableFrame ; 0 == default */<b>
   unsigned long long     contentSize;          </b>/* Size of uncompressed content ; 0 == unknown */<b>
-  unsigned               dictID;               </b>/* Dictionary ID, sent by the compressor, to help the decoder select the right dictionary; 0 == no dictionary used */<b>
+  unsigned               dictID;               </b>/* Dictionary ID, sent by the compressor to help decoder select the correct dictionary; 0 == no dictID provided */<b>
   unsigned               reserved[1];          </b>/* must be zero for forward compatibility */<b>
 } LZ4F_frameInfo_t;
 </b><p> makes it possible to supply detailed frame parameters to the stream interface.
diff --git a/lib/lz4.h b/lib/lz4.h
index c5b6103..86ca0d5 100644
--- a/lib/lz4.h
+++ b/lib/lz4.h
@@ -259,8 +259,8 @@ LZ4LIB_API int LZ4_loadDict (LZ4_stream_t* streamPtr, const char* dictionary, in
  *  Important : Previous data blocks are assumed to remain present and unmodified !
  *  'dst' buffer must be already allocated.
  *  If dstCapacity >= LZ4_compressBound(srcSize), compression is guaranteed to succeed, and runs faster.
- *  If not, and if compressed data cannot fit into 'dst' buffer size, compression stops, and function returns a zero.
- *  After an error, the stream status is invalid, and it can only be reset or freed.
+ *  If not, and if compressed data cannot fit into 'dst' buffer size, compression stops, and function @return==0.
+ *  After an error, the stream status is invalid, it can only be reset or freed.
  */
 LZ4LIB_API int LZ4_compress_fast_continue (LZ4_stream_t* streamPtr, const char* src, char* dst, int srcSize, int dstCapacity, int acceleration);
 
@@ -291,22 +291,21 @@ LZ4LIB_API int                 LZ4_freeStreamDecode (LZ4_streamDecode_t* LZ4_str
  */
 LZ4LIB_API int LZ4_setStreamDecode (LZ4_streamDecode_t* LZ4_streamDecode, const char* dictionary, int dictSize);
 
-/*!
-LZ4_decompress_*_continue() :
-    These decoding functions allow decompression of multiple blocks in "streaming" mode.
-    Previously decoded blocks *must* remain available at the memory position where they were decoded (up to 64 KB)
-    In the case of a ring buffers, decoding buffer must be either :
-    - Exactly same size as encoding buffer, with same update rule (block boundaries at same positions)
-      In which case, the decoding & encoding ring buffer can have any size, including very small ones ( < 64 KB).
-    - Larger than encoding buffer, by a minimum of maxBlockSize more bytes.
-      maxBlockSize is implementation dependent. It's the maximum size you intend to compress into a single block.
-      In which case, encoding and decoding buffers do not need to be synchronized,
-      and encoding ring buffer can have any size, including small ones ( < 64 KB).
-    - _At least_ 64 KB + 8 bytes + maxBlockSize.
-      In which case, encoding and decoding buffers do not need to be synchronized,
-      and encoding ring buffer can have any size, including larger than decoding buffer.
-    Whenever these conditions are not possible, save the last 64KB of decoded data into a safe buffer,
-    and indicate where it is saved using LZ4_setStreamDecode()
+/*! LZ4_decompress_*_continue() :
+ *  These decoding functions allow decompression of multiple blocks in "streaming" mode.
+ *  Previously decoded blocks *must* remain available at the memory position where they were decoded (up to 64 KB)
+ *  In the case of a ring buffers, decoding buffer must be either :
+ *  - Exactly same size as encoding buffer, with same update rule (block boundaries at same positions)
+ *    In which case, the decoding & encoding ring buffer can have any size, including very small ones ( < 64 KB).
+ *  - Larger than encoding buffer, by a minimum of maxBlockSize more bytes.
+ *    maxBlockSize is implementation dependent. It's the maximum size you intend to compress into a single block.
+ *    In which case, encoding and decoding buffers do not need to be synchronized,
+ *    and encoding ring buffer can have any size, including small ones ( < 64 KB).
+ *  - _At least_ 64 KB + 8 bytes + maxBlockSize.
+ *    In which case, encoding and decoding buffers do not need to be synchronized,
+ *    and encoding ring buffer can have any size, including larger than decoding buffer.
+ *  Whenever these conditions are not possible, save the last 64KB of decoded data into a safe buffer,
+ *  and indicate where it is saved using LZ4_setStreamDecode()
 */
 LZ4LIB_API int LZ4_decompress_safe_continue (LZ4_streamDecode_t* LZ4_streamDecode, const char* source, char* dest, int compressedSize, int maxDecompressedSize);
 LZ4LIB_API int LZ4_decompress_fast_continue (LZ4_streamDecode_t* LZ4_streamDecode, const char* source, char* dest, int originalSize);
@@ -458,6 +457,7 @@ LZ4LIB_API LZ4_DEPRECATED("use LZ4_decompress_fast_usingDict() instead") int LZ4
 
 #endif /* LZ4_H_2983827168210 */
 
+
 #if defined (__cplusplus)
 }
 #endif
diff --git a/lib/lz4frame.c b/lib/lz4frame.c
index 180658d..9aeb456 100644
--- a/lib/lz4frame.c
+++ b/lib/lz4frame.c
@@ -61,6 +61,7 @@ You can contact the author at :
 **************************************/
 #include "lz4frame_static.h"
 #include "lz4.h"
+#define LZ4_HC_STATIC_LINKING_ONLY
 #include "lz4hc.h"
 #define XXH_STATIC_LINKING_ONLY
 #include "xxhash.h"
@@ -217,6 +218,8 @@ static LZ4F_errorCode_t err0r(LZ4F_errorCodes code)
 
 unsigned LZ4F_getVersion(void) { return LZ4F_VERSION; }
 
+int LZ4F_compressionLevel_max(void) { return LZ4HC_CLEVEL_MAX; }
+
 
 /*-************************************
 *  Private functions
@@ -308,7 +311,7 @@ size_t LZ4F_compressFrameBound(size_t srcSize, const LZ4F_preferences_t* prefere
  *  dstBuffer MUST be >= LZ4F_compressFrameBound(srcSize, preferencesPtr).
  *  The LZ4F_preferences_t structure is optional : you may provide NULL as argument,
  *  however, it's the only way to provide a dictID, so it's not recommended.
- * @return : number of bytes written into dstBuffer.
+ * @return : number of bytes written into dstBuffer,
  *           or an error code if it fails (can be tested using LZ4F_isError())
  */
 size_t LZ4F_compressFrame_usingCDict(void* dstBuffer, size_t dstCapacity,
@@ -535,8 +538,10 @@ size_t LZ4F_compressBegin_usingCDict(LZ4F_cctx* cctxPtr,
     if (cdict) {
         if (cctxPtr->prefs.compressionLevel < LZ4HC_CLEVEL_MIN) {
             memcpy(cctxPtr->lz4CtxPtr, cdict->fastCtx, sizeof(*cdict->fastCtx));
-        } else
+        } else {
             memcpy(cctxPtr->lz4CtxPtr, cdict->HCCtx, sizeof(*cdict->HCCtx));
+            LZ4_setCompressionLevel((LZ4_streamHC_t*)cctxPtr->lz4CtxPtr, cctxPtr->prefs.compressionLevel);
+        }
     } else {
         if (cctxPtr->prefs.compressionLevel < LZ4HC_CLEVEL_MIN)
             LZ4_resetStream((LZ4_stream_t*)(cctxPtr->lz4CtxPtr));
@@ -659,14 +664,12 @@ static int LZ4F_localSaveDict(LZ4F_cctx_t* cctxPtr)
 typedef enum { notDone, fromTmpBuffer, fromSrcBuffer } LZ4F_lastBlockStatus;
 
 /*! LZ4F_compressUpdate() :
-* LZ4F_compressUpdate() can be called repetitively to compress as much data as necessary.
-* The most important rule is that dstBuffer MUST be large enough (dstCapacity) to ensure compression completion even in worst case.
-* If this condition is not respected, LZ4F_compress() will fail (result is an errorCode)
-* You can get the minimum value of dstCapacity by using LZ4F_compressBound()
-* The LZ4F_compressOptions_t structure is optional : you can provide NULL as argument.
-* The result of the function is the number of bytes written into dstBuffer : it can be zero, meaning input data was just buffered.
-* The function outputs an error code if it fails (can be tested using LZ4F_isError())
-*/
+ *  LZ4F_compressUpdate() can be called repetitively to compress as much data as necessary.
+ *  dstBuffer MUST be >= LZ4F_compressBound(srcSize, preferencesPtr).
+ *  LZ4F_compressOptions_t structure is optional : you can provide NULL as argument.
+ * @return : the number of bytes written into dstBuffer. It can be zero, meaning input data was just buffered.
+ *           or an error code if it fails (which can be tested using LZ4F_isError())
+ */
 size_t LZ4F_compressUpdate(LZ4F_cctx* cctxPtr, void* dstBuffer, size_t dstCapacity, const void* srcBuffer, size_t srcSize, const LZ4F_compressOptions_t* compressOptionsPtr)
 {
     LZ4F_compressOptions_t cOptionsNull;
diff --git a/lib/lz4frame.h b/lib/lz4frame.h
index 42e2f53..307d7b2 100644
--- a/lib/lz4frame.h
+++ b/lib/lz4frame.h
@@ -162,7 +162,7 @@ typedef struct {
   LZ4F_contentChecksum_t contentChecksumFlag;  /* noContentChecksum, contentChecksumEnabled ; 0 == default  */
   LZ4F_frameType_t       frameType;            /* LZ4F_frame, skippableFrame ; 0 == default */
   unsigned long long     contentSize;          /* Size of uncompressed content ; 0 == unknown */
-  unsigned               dictID;               /* Dictionary ID, sent by the compressor, to help the decoder select the right dictionary; 0 == no dictionary used */
+  unsigned               dictID;               /* Dictionary ID, sent by the compressor to help decoder select the correct dictionary; 0 == no dictID provided */
   unsigned               reserved[1];          /* must be zero for forward compatibility */
 } LZ4F_frameInfo_t;
 
@@ -177,6 +177,8 @@ typedef struct {
   unsigned reserved[4];            /* must be zero for forward compatibility */
 } LZ4F_preferences_t;
 
+LZ4FLIB_API int LZ4F_compressionLevel_max();
+
 
 /*-*********************************
 *  Simple compression function
diff --git a/lib/lz4hc.c b/lib/lz4hc.c
index b17760d..22eb071 100644
--- a/lib/lz4hc.c
+++ b/lib/lz4hc.c
@@ -69,6 +69,8 @@
 
 
 /*===   Macros   ===*/
+#define MIN(a,b)   ( (a) < (b) ? (a) : (b) )
+#define MAX(a,b)   ( (a) > (b) ? (a) : (b) )
 #define HASH_FUNCTION(i)         (((i) * 2654435761U) >> ((MINMATCH*8)-LZ4HC_HASH_LOG))
 #define DELTANEXTMAXD(p)         chainTable[(p) & LZ4HC_MAXD_MASK]    /* flexible, LZ4HC_MAXD dependent */
 #define DELTANEXTU16(table, pos) table[(U16)(pos)]   /* faster */
@@ -627,6 +629,16 @@ void LZ4_resetStreamHC (LZ4_streamHC_t* LZ4_streamHCPtr, int compressionLevel)
     LZ4_streamHCPtr->internal_donotuse.searchNum = LZ4HC_getSearchNum(compressionLevel);
 }
 
+void LZ4_setCompressionLevel(LZ4_streamHC_t* LZ4_streamHCPtr, int compressionLevel)
+{
+    int const currentCLevel = LZ4_streamHCPtr->internal_donotuse.compressionLevel;
+    int const minCLevel = currentCLevel < LZ4HC_CLEVEL_OPT_MIN ? 1 : LZ4HC_CLEVEL_OPT_MIN;
+    int const maxCLevel = currentCLevel < LZ4HC_CLEVEL_OPT_MIN ? LZ4HC_CLEVEL_OPT_MIN-1 : LZ4HC_CLEVEL_MAX;
+    compressionLevel = MIN(compressionLevel, minCLevel);
+    compressionLevel = MAX(compressionLevel, maxCLevel);
+    LZ4_streamHCPtr->internal_donotuse.compressionLevel = compressionLevel;
+}
+
 int LZ4_loadDictHC (LZ4_streamHC_t* LZ4_streamHCPtr, const char* dictionary, int dictSize)
 {
     LZ4HC_CCtx_internal* const ctxPtr = &LZ4_streamHCPtr->internal_donotuse;
diff --git a/lib/lz4hc.h b/lib/lz4hc.h
index b63c825..66d5636 100644
--- a/lib/lz4hc.h
+++ b/lib/lz4hc.h
@@ -161,7 +161,7 @@ typedef struct
 typedef struct
 {
     unsigned int   hashTable[LZ4HC_HASHTABLESIZE];
-    unsigned short   chainTable[LZ4HC_MAXD];
+    unsigned short chainTable[LZ4HC_MAXD];
     const unsigned char* end;        /* next block here to continue on current prefix */
     const unsigned char* base;       /* All index relative to this position */
     const unsigned char* dictBase;   /* alternate base for extDict */
@@ -245,25 +245,34 @@ LZ4LIB_API LZ4_DEPRECATED("use LZ4_resetStreamHC() instead")  int   LZ4_resetStr
  *           or 0 if compression fails.
  * `srcSizePtr` : value will be updated to indicate how much bytes were read from `src`
  */
-LZ4LIB_API int LZ4_compress_HC_destSize(void* LZ4HC_Data,
+int LZ4_compress_HC_destSize(void* LZ4HC_Data,
                             const char* src, char* dst,
                             int* srcSizePtr, int targetDstSize,
                             int compressionLevel);
 
-/*! LZ4_compress_HC_continue_destSize() :
+/*! LZ4_compress_HC_continue_destSize() : v1.8.0 (experimental)
  *  Similar as LZ4_compress_HC_continue(),
  *  but will read a variable nb of bytes from `src`
  *  to fit into `targetDstSize` budget.
  *  Result is provided in 2 parts :
  * @return : the number of bytes written into 'dst'
  *           or 0 if compression fails.
- * `srcSizePtr` : value will be updated to indicate how much bytes were read from `src`
- * Important : due to limitations, this prototype only works well up to cLevel < LZ4HC_CLEVEL_OPT_MIN
- *             beyond that level, compression performance will be much reduced due to internal incompatibilities
+ * `srcSizePtr` : value will be updated to indicate how much bytes were read from `src`.
+ *  Important : due to limitations, this prototype only works well up to cLevel < LZ4HC_CLEVEL_OPT_MIN
+ *              beyond that level, compression performance will be much reduced due to internal incompatibilities
  */
-LZ4LIB_API int LZ4_compress_HC_continue_destSize(LZ4_streamHC_t* LZ4_streamHCPtr,
+int LZ4_compress_HC_continue_destSize(LZ4_streamHC_t* LZ4_streamHCPtr,
                             const char* src, char* dst,
                             int* srcSizePtr, int targetDstSize);
 
+/*! LZ4_setCompressionLevel() : v1.8.0 (experimental)
+ *  It's possible to change compression level after LZ4_resetStreamHC(), between 2 invocations of LZ4_compress_HC_continue*(),
+ *  but that requires to stay in the same mode (aka 1-10 or 11-12).
+ *  This function ensures this condition.
+ */
+void LZ4_setCompressionLevel(LZ4_streamHC_t* LZ4_streamHCPtr, int compressionLevel);
+
+
+
 #endif   /* LZ4_HC_SLO_098092834 */
 #endif   /* LZ4_HC_STATIC_LINKING_ONLY */
diff --git a/tests/frametest.c b/tests/frametest.c
index 1ee0d96..4723aac 100644
--- a/tests/frametest.c
+++ b/tests/frametest.c
@@ -508,6 +508,30 @@ int basicTests(U32 seed, double compressibility)
         DISPLAYLEVEL(3, "%u bytes \n", (unsigned)cSizeWithDict);
         if (cSizeWithDict >= cSizeNoDict) goto _output_error;  /* must be more efficient */
 
+        DISPLAYLEVEL(3, "LZ4F_compressFrame_usingCDict, with dict, negative level : ");
+        {   size_t cSizeLevelMax;
+            LZ4F_preferences_t cParams;
+            memset(&cParams, 0, sizeof(cParams));
+            cParams.compressionLevel = -3;
+            CHECK_V(cSizeLevelMax,
+                LZ4F_compressFrame_usingCDict(compressedBuffer, dstCapacity,
+                                              CNBuffer, dictSize,
+                                              cdict, &cParams) );
+            DISPLAYLEVEL(3, "%u bytes \n", (unsigned)cSizeLevelMax);
+        }
+
+        DISPLAYLEVEL(3, "LZ4F_compressFrame_usingCDict, with dict, level max : ");
+        {   size_t cSizeLevelMax;
+            LZ4F_preferences_t cParams;
+            memset(&cParams, 0, sizeof(cParams));
+            cParams.compressionLevel = LZ4F_compressionLevel_max();
+            CHECK_V(cSizeLevelMax,
+                LZ4F_compressFrame_usingCDict(compressedBuffer, dstCapacity,
+                                              CNBuffer, dictSize,
+                                              cdict, &cParams) );
+            DISPLAYLEVEL(3, "%u bytes \n", (unsigned)cSizeLevelMax);
+        }
+
         LZ4F_freeCDict(cdict);
     }
 
-- 
cgit v0.12


From 8d597d62d5455f5d315782048b9d32f129a60bac Mon Sep 17 00:00:00 2001
From: Yann Collet <cyan@fb.com>
Date: Thu, 10 Aug 2017 10:28:52 -0700
Subject: fixed gcc prototype warning

---
 doc/lz4_manual.html | 4 ----
 lib/lz4frame.h      | 2 +-
 2 files changed, 1 insertion(+), 5 deletions(-)

diff --git a/doc/lz4_manual.html b/doc/lz4_manual.html
index ecc985d..9ab1984 100644
--- a/doc/lz4_manual.html
+++ b/doc/lz4_manual.html
@@ -321,9 +321,5 @@ union LZ4_streamDecode_u {
    Otherwise, it's also possible to define LZ4_DISABLE_DEPRECATE_WARNINGS 
 </p></pre><BR>
 
-<h3>Experimental API section</h3><pre></pre><b><pre>#ifdef LZ4_HC_STATIC_LINKING_ONLY
-#ifndef LZ4_SLO_299387928743
-#define LZ4_SLO_299387928743
-</pre></b><BR>
 </html>
 </body>
diff --git a/lib/lz4frame.h b/lib/lz4frame.h
index 307d7b2..ccacb89 100644
--- a/lib/lz4frame.h
+++ b/lib/lz4frame.h
@@ -177,7 +177,7 @@ typedef struct {
   unsigned reserved[4];            /* must be zero for forward compatibility */
 } LZ4F_preferences_t;
 
-LZ4FLIB_API int LZ4F_compressionLevel_max();
+LZ4FLIB_API int LZ4F_compressionLevel_max(void);
 
 
 /*-*********************************
-- 
cgit v0.12


From 4531637ecdc4b12154c66cc69cfaade185039e4c Mon Sep 17 00:00:00 2001
From: Yann Collet <cyan@fb.com>
Date: Thu, 10 Aug 2017 12:12:53 -0700
Subject: support dictionary compression with independent blocks

---
 doc/lz4frame_manual.html | 55 ++++++++++++++++----------------
 lib/lz4frame.c           | 82 ++++++++++++++++++++++++++++++------------------
 lib/lz4frame.h           | 63 +++++++++++++++++++------------------
 tests/frametest.c        | 30 ++++++++++++++++++
 4 files changed, 141 insertions(+), 89 deletions(-)

diff --git a/doc/lz4frame_manual.html b/doc/lz4frame_manual.html
index a1a6e96..9593181 100644
--- a/doc/lz4frame_manual.html
+++ b/doc/lz4frame_manual.html
@@ -96,8 +96,8 @@
 <a name="Chapter5"></a><h2>Simple compression function</h2><pre></pre>
 
 <pre><b>size_t LZ4F_compressFrameBound(size_t srcSize, const LZ4F_preferences_t* preferencesPtr);
-</b><p> Returns the maximum possible size of a frame compressed with LZ4F_compressFrame() given srcSize content and preferences.
- Note : this result is only usable with LZ4F_compressFrame(), not with multi-segments compression.
+</b><p>  Returns the maximum possible size of a frame compressed with LZ4F_compressFrame() given srcSize content and preferences.
+  Note : this result is only usable with LZ4F_compressFrame(), not with multi-segments compression.
  
 </p></pre><BR>
 
@@ -210,10 +210,10 @@ LZ4F_errorCode_t LZ4F_freeDecompressionContext(LZ4F_dctx* dctx);
 <pre><b>size_t LZ4F_getFrameInfo(LZ4F_dctx* dctx,
                                      LZ4F_frameInfo_t* frameInfoPtr,
                                      const void* srcBuffer, size_t* srcSizePtr);
-</b><p> This function extracts frame parameters (such as max blockSize, frame checksum, etc.).
- Its usage is optional.
- Extracted information can typically be useful for allocation purposes.
- This function works in 2 situations :
+</b><p>  This function extracts frame parameters (max blockSize, dictID, etc.).
+  Its usage is optional.
+  Extracted information is typically useful for allocation and dictionary.
+  This function works in 2 situations :
    - At the beginning of a new frame, in which case
      it will decode information from `srcBuffer`, starting the decoding process.
      Input size must be large enough to successfully decode the entire frame header.
@@ -221,13 +221,14 @@ LZ4F_errorCode_t LZ4F_freeDecompressionContext(LZ4F_dctx* dctx);
      It's allowed to provide more input data than this minimum.
    - After decoding has been started.
      In which case, no input is read, frame parameters are extracted from dctx.
-   - If decoding has barely started, but not yet extracted information from header, LZ4F_getFrameInfo() will fail.
- The number of bytes consumed from srcBuffer will be updated within *srcSizePtr (necessarily <= original value).
- Decompression must resume from (srcBuffer + *srcSizePtr).
+   - If decoding has barely started, but not yet extracted information from header,
+     LZ4F_getFrameInfo() will fail.
+  The number of bytes consumed from srcBuffer will be updated within *srcSizePtr (necessarily <= original value).
+  Decompression must resume from (srcBuffer + *srcSizePtr).
  @return : an hint about how many srcSize bytes LZ4F_decompress() expects for next call,
-           or an error code which can be tested using LZ4F_isError()
- note 1 : in case of error, dctx is not modified. Decoding operation can resume safely.
- note 2 : frame parameters are *copied into* an already allocated LZ4F_frameInfo_t structure.
+           or an error code which can be tested using LZ4F_isError().
+  note 1 : in case of error, dctx is not modified. Decoding operation can resume from beginning safely.
+  note 2 : frame parameters are *copied into* an already allocated LZ4F_frameInfo_t structure.
  
 </p></pre><BR>
 
@@ -235,28 +236,28 @@ LZ4F_errorCode_t LZ4F_freeDecompressionContext(LZ4F_dctx* dctx);
                                    void* dstBuffer, size_t* dstSizePtr,
                                    const void* srcBuffer, size_t* srcSizePtr,
                                    const LZ4F_decompressOptions_t* dOptPtr);
-</b><p> Call this function repetitively to regenerate compressed data from `srcBuffer`.
- The function will attempt to decode up to *srcSizePtr bytes from srcBuffer, into dstBuffer of capacity *dstSizePtr.
+</b><p>  Call this function repetitively to regenerate compressed data from `srcBuffer`.
+  The function will attempt to decode up to *srcSizePtr bytes from srcBuffer, into dstBuffer of capacity *dstSizePtr.
 
- The number of bytes regenerated into dstBuffer is provided within *dstSizePtr (necessarily <= original value).
+  The number of bytes regenerated into dstBuffer is provided within *dstSizePtr (necessarily <= original value).
 
- The number of bytes consumed from srcBuffer is provided within *srcSizePtr (necessarily <= original value).
- Number of bytes consumed can be < number of bytes provided.
- It typically happens when dstBuffer is not large enough to contain all decoded data.
- Unconsumed source data must be presented again in subsequent invocations.
+  The number of bytes consumed from srcBuffer is provided within *srcSizePtr (necessarily <= original value).
+  Number of bytes consumed can be < number of bytes provided.
+  It typically happens when dstBuffer is not large enough to contain all decoded data.
+  Unconsumed source data must be presented again in subsequent invocations.
 
  `dstBuffer` content is expected to be flushed between each invocation, as its content will be overwritten.
  `dstBuffer` itself can be changed at will between each consecutive function invocation.
 
- @return is an hint of how many `srcSize` bytes LZ4F_decompress() expects for next call.
- Schematically, it's the size of the current (or remaining) compressed block + header of next block.
- Respecting the hint provides some small speed benefit, because it skips intermediate buffers.
- This is just a hint though, it's always possible to provide any srcSize.
- When a frame is fully decoded, @return will be 0 (no more data expected).
- If decompression failed, @return is an error code, which can be tested using LZ4F_isError().
+ @return : an hint of how many `srcSize` bytes LZ4F_decompress() expects for next call.
+  Schematically, it's the size of the current (or remaining) compressed block + header of next block.
+  Respecting the hint provides some small speed benefit, because it skips intermediate buffers.
+  This is just a hint though, it's always possible to provide any srcSize.
+  When a frame is fully decoded, @return will be 0 (no more data expected).
+  If decompression failed, @return is an error code, which can be tested using LZ4F_isError().
 
- After a frame is fully decoded, dctx can be used again to decompress another frame.
- After a decompression error, use LZ4F_resetDecompressionContext() before re-using dctx, to return to clean state.
+  After a frame is fully decoded, dctx can be used again to decompress another frame.
+  After a decompression error, use LZ4F_resetDecompressionContext() before re-using dctx, to return to clean state.
  
 </p></pre><BR>
 
diff --git a/lib/lz4frame.c b/lib/lz4frame.c
index 9aeb456..fbccc9d 100644
--- a/lib/lz4frame.c
+++ b/lib/lz4frame.c
@@ -171,7 +171,7 @@ typedef struct LZ4F_cctx_s
     LZ4F_preferences_t prefs;
     U32    version;
     U32    cStage;
-    int    dictionary;
+    const LZ4F_CDict* cdict;
     size_t maxBlockSize;
     size_t maxBufferSize;
     BYTE*  tmpBuff;
@@ -534,19 +534,22 @@ size_t LZ4F_compressBegin_usingCDict(LZ4F_cctx* cctxPtr,
     XXH32_reset(&(cctxPtr->xxh), 0);
 
     /* context init */
-    cctxPtr->dictionary = (cdict!=NULL);
-    if (cdict) {
-        if (cctxPtr->prefs.compressionLevel < LZ4HC_CLEVEL_MIN) {
-            memcpy(cctxPtr->lz4CtxPtr, cdict->fastCtx, sizeof(*cdict->fastCtx));
+    cctxPtr->cdict = cdict;
+    if (cctxPtr->prefs.frameInfo.blockMode == LZ4F_blockLinked) {
+        /* frame init only for blockLinked : blockIndependent will be init at each block */
+        if (cdict) {
+            if (cctxPtr->prefs.compressionLevel < LZ4HC_CLEVEL_MIN) {
+                memcpy(cctxPtr->lz4CtxPtr, cdict->fastCtx, sizeof(*cdict->fastCtx));
+            } else {
+                memcpy(cctxPtr->lz4CtxPtr, cdict->HCCtx, sizeof(*cdict->HCCtx));
+                LZ4_setCompressionLevel((LZ4_streamHC_t*)cctxPtr->lz4CtxPtr, cctxPtr->prefs.compressionLevel);
+            }
         } else {
-            memcpy(cctxPtr->lz4CtxPtr, cdict->HCCtx, sizeof(*cdict->HCCtx));
-            LZ4_setCompressionLevel((LZ4_streamHC_t*)cctxPtr->lz4CtxPtr, cctxPtr->prefs.compressionLevel);
+            if (cctxPtr->prefs.compressionLevel < LZ4HC_CLEVEL_MIN)
+                LZ4_resetStream((LZ4_stream_t*)(cctxPtr->lz4CtxPtr));
+            else
+                LZ4_resetStreamHC((LZ4_streamHC_t*)(cctxPtr->lz4CtxPtr), cctxPtr->prefs.compressionLevel);
         }
-    } else {
-        if (cctxPtr->prefs.compressionLevel < LZ4HC_CLEVEL_MIN)
-            LZ4_resetStream((LZ4_stream_t*)(cctxPtr->lz4CtxPtr));
-        else
-            LZ4_resetStreamHC((LZ4_streamHC_t*)(cctxPtr->lz4CtxPtr), cctxPtr->prefs.compressionLevel);
     }
 
     /* Magic Number */
@@ -609,13 +612,15 @@ size_t LZ4F_compressBound(size_t srcSize, const LZ4F_preferences_t* preferencesP
 }
 
 
-typedef int (*compressFunc_t)(void* ctx, const char* src, char* dst, int srcSize, int dstSize, int level);
+typedef int (*compressFunc_t)(void* ctx, const char* src, char* dst, int srcSize, int dstSize, int level, const LZ4F_CDict* cdict);
 
-static size_t LZ4F_compressBlock(void* dst, const void* src, size_t srcSize, compressFunc_t compress, void* lz4ctx, int level)
+static size_t LZ4F_makeBlock(void* dst, const void* src, size_t srcSize, compressFunc_t compress, void* lz4ctx, int level, const LZ4F_CDict* cdict)
 {
     /* compress a single block */
     BYTE* const cSizePtr = (BYTE*)dst;
-    U32 cSize = (U32)compress(lz4ctx, (const char*)src, (char*)(cSizePtr+4), (int)(srcSize), (int)(srcSize-1), level);
+    U32 cSize = (U32)compress(lz4ctx, (const char*)src, (char*)(cSizePtr+4),
+                                      (int)(srcSize), (int)(srcSize-1),
+                                      level, cdict);
     LZ4F_writeLE32(cSizePtr, cSize);
     if (cSize == 0) {  /* compression failed */
         cSize = (U32)srcSize;
@@ -626,32 +631,47 @@ static size_t LZ4F_compressBlock(void* dst, const void* src, size_t srcSize, com
 }
 
 
-static int LZ4F_localLZ4_compress_limitedOutput_withState(void* ctx, const char* src, char* dst, int srcSize, int dstCapacity, int level)
+static int LZ4F_compressBlock(void* ctx, const char* src, char* dst, int srcSize, int dstCapacity, int level, const LZ4F_CDict* cdict)
 {
     int const acceleration = (level < -1) ? -level : 1;
+    if (cdict) {
+        memcpy(ctx, cdict->fastCtx, sizeof(*cdict->fastCtx));
+        return LZ4_compress_fast_continue((LZ4_stream_t*)ctx, src, dst, srcSize, dstCapacity, acceleration);
+    }
     return LZ4_compress_fast_extState(ctx, src, dst, srcSize, dstCapacity, acceleration);
 }
 
-static int LZ4F_localLZ4_compress_limitedOutput_continue(void* ctx, const char* src, char* dst, int srcSize, int dstCapacity, int level)
+static int LZ4F_compressBlock_continue(void* ctx, const char* src, char* dst, int srcSize, int dstCapacity, int level, const LZ4F_CDict* cdict)
 {
     int const acceleration = (level < -1) ? -level : 1;
+    (void)cdict; /* init once at beginning of frame */
     return LZ4_compress_fast_continue((LZ4_stream_t*)ctx, src, dst, srcSize, dstCapacity, acceleration);
 }
 
-static int LZ4F_localLZ4_compressHC_limitedOutput_continue(void* ctx, const char* src, char* dst, int srcSize, int dstCapacity, int level)
+static int LZ4F_compressBlockHC(void* ctx, const char* src, char* dst, int srcSize, int dstCapacity, int level, const LZ4F_CDict* cdict)
+{
+    if (cdict) {
+        memcpy(ctx, cdict->HCCtx, sizeof(*cdict->HCCtx));
+        LZ4_setCompressionLevel((LZ4_streamHC_t*)ctx, level);
+        return LZ4_compress_HC_continue((LZ4_streamHC_t*)ctx, src, dst, srcSize, dstCapacity);
+    }
+    return LZ4_compress_HC_extStateHC(ctx, src, dst, srcSize, dstCapacity, level);
+}
+
+static int LZ4F_compressBlockHC_continue(void* ctx, const char* src, char* dst, int srcSize, int dstCapacity, int level, const LZ4F_CDict* cdict)
 {
-    (void) level;
+    (void)level; (void)cdict; /* init once at beginning of frame */
     return LZ4_compress_HC_continue((LZ4_streamHC_t*)ctx, src, dst, srcSize, dstCapacity);
 }
 
-static compressFunc_t LZ4F_selectCompression(LZ4F_blockMode_t blockMode, int dictionary, int level)
+static compressFunc_t LZ4F_selectCompression(LZ4F_blockMode_t blockMode, int level)
 {
     if (level < LZ4HC_CLEVEL_MIN) {
-        if (blockMode == LZ4F_blockIndependent && !dictionary) return LZ4F_localLZ4_compress_limitedOutput_withState;
-        return LZ4F_localLZ4_compress_limitedOutput_continue;
+        if (blockMode == LZ4F_blockIndependent) return LZ4F_compressBlock;
+        return LZ4F_compressBlock_continue;
     }
-    if (blockMode == LZ4F_blockIndependent && !dictionary) return LZ4_compress_HC_extStateHC;
-    return LZ4F_localLZ4_compressHC_limitedOutput_continue;
+    if (blockMode == LZ4F_blockIndependent) return LZ4F_compressBlockHC;
+    return LZ4F_compressBlockHC_continue;
 }
 
 static int LZ4F_localSaveDict(LZ4F_cctx_t* cctxPtr)
@@ -679,7 +699,7 @@ size_t LZ4F_compressUpdate(LZ4F_cctx* cctxPtr, void* dstBuffer, size_t dstCapaci
     BYTE* const dstStart = (BYTE*)dstBuffer;
     BYTE* dstPtr = dstStart;
     LZ4F_lastBlockStatus lastBlockCompressed = notDone;
-    compressFunc_t const compress = LZ4F_selectCompression(cctxPtr->prefs.frameInfo.blockMode, cctxPtr->dictionary, cctxPtr->prefs.compressionLevel);
+    compressFunc_t const compress = LZ4F_selectCompression(cctxPtr->prefs.frameInfo.blockMode, cctxPtr->prefs.compressionLevel);
 
 
     if (cctxPtr->cStage != 1) return err0r(LZ4F_ERROR_GENERIC);
@@ -702,7 +722,7 @@ size_t LZ4F_compressUpdate(LZ4F_cctx* cctxPtr, void* dstBuffer, size_t dstCapaci
             memcpy(cctxPtr->tmpIn + cctxPtr->tmpInSize, srcBuffer, sizeToCopy);
             srcPtr += sizeToCopy;
 
-            dstPtr += LZ4F_compressBlock(dstPtr, cctxPtr->tmpIn, blockSize, compress, cctxPtr->lz4CtxPtr, cctxPtr->prefs.compressionLevel);
+            dstPtr += LZ4F_makeBlock(dstPtr, cctxPtr->tmpIn, blockSize, compress, cctxPtr->lz4CtxPtr, cctxPtr->prefs.compressionLevel, cctxPtr->cdict);
 
             if (cctxPtr->prefs.frameInfo.blockMode==LZ4F_blockLinked) cctxPtr->tmpIn += blockSize;
             cctxPtr->tmpInSize = 0;
@@ -710,16 +730,16 @@ size_t LZ4F_compressUpdate(LZ4F_cctx* cctxPtr, void* dstBuffer, size_t dstCapaci
     }
 
     while ((size_t)(srcEnd - srcPtr) >= blockSize) {
-        /* compress full block */
+        /* compress full blocks */
         lastBlockCompressed = fromSrcBuffer;
-        dstPtr += LZ4F_compressBlock(dstPtr, srcPtr, blockSize, compress, cctxPtr->lz4CtxPtr, cctxPtr->prefs.compressionLevel);
+        dstPtr += LZ4F_makeBlock(dstPtr, srcPtr, blockSize, compress, cctxPtr->lz4CtxPtr, cctxPtr->prefs.compressionLevel, cctxPtr->cdict);
         srcPtr += blockSize;
     }
 
     if ((cctxPtr->prefs.autoFlush) && (srcPtr < srcEnd)) {
         /* compress remaining input < blockSize */
         lastBlockCompressed = fromSrcBuffer;
-        dstPtr += LZ4F_compressBlock(dstPtr, srcPtr, srcEnd - srcPtr, compress, cctxPtr->lz4CtxPtr, cctxPtr->prefs.compressionLevel);
+        dstPtr += LZ4F_makeBlock(dstPtr, srcPtr, srcEnd - srcPtr, compress, cctxPtr->lz4CtxPtr, cctxPtr->prefs.compressionLevel, cctxPtr->cdict);
         srcPtr  = srcEnd;
     }
 
@@ -778,10 +798,10 @@ size_t LZ4F_flush(LZ4F_cctx* cctxPtr, void* dstBuffer, size_t dstCapacity, const
     (void)compressOptionsPtr;   /* not yet useful */
 
     /* select compression function */
-    compress = LZ4F_selectCompression(cctxPtr->prefs.frameInfo.blockMode, cctxPtr->dictionary, cctxPtr->prefs.compressionLevel);
+    compress = LZ4F_selectCompression(cctxPtr->prefs.frameInfo.blockMode, cctxPtr->prefs.compressionLevel);
 
     /* compress tmp buffer */
-    dstPtr += LZ4F_compressBlock(dstPtr, cctxPtr->tmpIn, cctxPtr->tmpInSize, compress, cctxPtr->lz4CtxPtr, cctxPtr->prefs.compressionLevel);
+    dstPtr += LZ4F_makeBlock(dstPtr, cctxPtr->tmpIn, cctxPtr->tmpInSize, compress, cctxPtr->lz4CtxPtr, cctxPtr->prefs.compressionLevel, cctxPtr->cdict);
     if (cctxPtr->prefs.frameInfo.blockMode==LZ4F_blockLinked) cctxPtr->tmpIn += cctxPtr->tmpInSize;
     cctxPtr->tmpInSize = 0;
 
diff --git a/lib/lz4frame.h b/lib/lz4frame.h
index ccacb89..dd76194 100644
--- a/lib/lz4frame.h
+++ b/lib/lz4frame.h
@@ -100,8 +100,8 @@ LZ4FLIB_API const char* LZ4F_getErrorName(LZ4F_errorCode_t code);   /**< return
 /*-************************************
  *  Frame compression types
  **************************************/
-/* #define LZ4F_DISABLE_OBSOLETE_ENUMS */  /* uncomment to disable obsolete enums */
-#ifndef LZ4F_DISABLE_OBSOLETE_ENUMS
+/* #define LZ4F_ENABLE_OBSOLETE_ENUMS   // uncomment to enable obsolete enums */
+#ifdef LZ4F_ENABLE_OBSOLETE_ENUMS
 #  define LZ4F_OBSOLETE_ENUM(x) , LZ4F_DEPRECATE(x) = LZ4F_##x
 #else
 #  define LZ4F_OBSOLETE_ENUM(x)
@@ -145,7 +145,7 @@ typedef enum {
     LZ4F_OBSOLETE_ENUM(skippableFrame)
 } LZ4F_frameType_t;
 
-#ifndef LZ4F_DISABLE_OBSOLETE_ENUMS
+#ifdef LZ4F_ENABLE_OBSOLETE_ENUMS
 typedef LZ4F_blockSizeID_t blockSizeID_t;
 typedef LZ4F_blockMode_t blockMode_t;
 typedef LZ4F_frameType_t frameType_t;
@@ -183,9 +183,9 @@ LZ4FLIB_API int LZ4F_compressionLevel_max(void);
 /*-*********************************
 *  Simple compression function
 ***********************************/
-/*!LZ4F_compressFrameBound() :
- * Returns the maximum possible size of a frame compressed with LZ4F_compressFrame() given srcSize content and preferences.
- * Note : this result is only usable with LZ4F_compressFrame(), not with multi-segments compression.
+/*! LZ4F_compressFrameBound() :
+ *  Returns the maximum possible size of a frame compressed with LZ4F_compressFrame() given srcSize content and preferences.
+ *  Note : this result is only usable with LZ4F_compressFrame(), not with multi-segments compression.
  */
 LZ4FLIB_API size_t LZ4F_compressFrameBound(size_t srcSize, const LZ4F_preferences_t* preferencesPtr);
 
@@ -316,10 +316,10 @@ LZ4FLIB_API LZ4F_errorCode_t LZ4F_freeDecompressionContext(LZ4F_dctx* dctx);
 *************************************/
 
 /*! LZ4F_getFrameInfo() :
- * This function extracts frame parameters (such as max blockSize, frame checksum, etc.).
- * Its usage is optional.
- * Extracted information can typically be useful for allocation purposes.
- * This function works in 2 situations :
+ *  This function extracts frame parameters (max blockSize, dictID, etc.).
+ *  Its usage is optional.
+ *  Extracted information is typically useful for allocation and dictionary.
+ *  This function works in 2 situations :
  *   - At the beginning of a new frame, in which case
  *     it will decode information from `srcBuffer`, starting the decoding process.
  *     Input size must be large enough to successfully decode the entire frame header.
@@ -327,41 +327,42 @@ LZ4FLIB_API LZ4F_errorCode_t LZ4F_freeDecompressionContext(LZ4F_dctx* dctx);
  *     It's allowed to provide more input data than this minimum.
  *   - After decoding has been started.
  *     In which case, no input is read, frame parameters are extracted from dctx.
- *   - If decoding has barely started, but not yet extracted information from header, LZ4F_getFrameInfo() will fail.
- * The number of bytes consumed from srcBuffer will be updated within *srcSizePtr (necessarily <= original value).
- * Decompression must resume from (srcBuffer + *srcSizePtr).
+ *   - If decoding has barely started, but not yet extracted information from header,
+ *     LZ4F_getFrameInfo() will fail.
+ *  The number of bytes consumed from srcBuffer will be updated within *srcSizePtr (necessarily <= original value).
+ *  Decompression must resume from (srcBuffer + *srcSizePtr).
  * @return : an hint about how many srcSize bytes LZ4F_decompress() expects for next call,
- *           or an error code which can be tested using LZ4F_isError()
- * note 1 : in case of error, dctx is not modified. Decoding operation can resume safely.
- * note 2 : frame parameters are *copied into* an already allocated LZ4F_frameInfo_t structure.
+ *           or an error code which can be tested using LZ4F_isError().
+ *  note 1 : in case of error, dctx is not modified. Decoding operation can resume from beginning safely.
+ *  note 2 : frame parameters are *copied into* an already allocated LZ4F_frameInfo_t structure.
  */
 LZ4FLIB_API size_t LZ4F_getFrameInfo(LZ4F_dctx* dctx,
                                      LZ4F_frameInfo_t* frameInfoPtr,
                                      const void* srcBuffer, size_t* srcSizePtr);
 
 /*! LZ4F_decompress() :
- * Call this function repetitively to regenerate compressed data from `srcBuffer`.
- * The function will attempt to decode up to *srcSizePtr bytes from srcBuffer, into dstBuffer of capacity *dstSizePtr.
+ *  Call this function repetitively to regenerate compressed data from `srcBuffer`.
+ *  The function will attempt to decode up to *srcSizePtr bytes from srcBuffer, into dstBuffer of capacity *dstSizePtr.
  *
- * The number of bytes regenerated into dstBuffer is provided within *dstSizePtr (necessarily <= original value).
+ *  The number of bytes regenerated into dstBuffer is provided within *dstSizePtr (necessarily <= original value).
  *
- * The number of bytes consumed from srcBuffer is provided within *srcSizePtr (necessarily <= original value).
- * Number of bytes consumed can be < number of bytes provided.
- * It typically happens when dstBuffer is not large enough to contain all decoded data.
- * Unconsumed source data must be presented again in subsequent invocations.
+ *  The number of bytes consumed from srcBuffer is provided within *srcSizePtr (necessarily <= original value).
+ *  Number of bytes consumed can be < number of bytes provided.
+ *  It typically happens when dstBuffer is not large enough to contain all decoded data.
+ *  Unconsumed source data must be presented again in subsequent invocations.
  *
  * `dstBuffer` content is expected to be flushed between each invocation, as its content will be overwritten.
  * `dstBuffer` itself can be changed at will between each consecutive function invocation.
  *
- * @return is an hint of how many `srcSize` bytes LZ4F_decompress() expects for next call.
- * Schematically, it's the size of the current (or remaining) compressed block + header of next block.
- * Respecting the hint provides some small speed benefit, because it skips intermediate buffers.
- * This is just a hint though, it's always possible to provide any srcSize.
- * When a frame is fully decoded, @return will be 0 (no more data expected).
- * If decompression failed, @return is an error code, which can be tested using LZ4F_isError().
+ * @return : an hint of how many `srcSize` bytes LZ4F_decompress() expects for next call.
+ *  Schematically, it's the size of the current (or remaining) compressed block + header of next block.
+ *  Respecting the hint provides some small speed benefit, because it skips intermediate buffers.
+ *  This is just a hint though, it's always possible to provide any srcSize.
+ *  When a frame is fully decoded, @return will be 0 (no more data expected).
+ *  If decompression failed, @return is an error code, which can be tested using LZ4F_isError().
  *
- * After a frame is fully decoded, dctx can be used again to decompress another frame.
- * After a decompression error, use LZ4F_resetDecompressionContext() before re-using dctx, to return to clean state.
+ *  After a frame is fully decoded, dctx can be used again to decompress another frame.
+ *  After a decompression error, use LZ4F_resetDecompressionContext() before re-using dctx, to return to clean state.
  */
 LZ4FLIB_API size_t LZ4F_decompress(LZ4F_dctx* dctx,
                                    void* dstBuffer, size_t* dstSizePtr,
diff --git a/tests/frametest.c b/tests/frametest.c
index 4723aac..a30089f 100644
--- a/tests/frametest.c
+++ b/tests/frametest.c
@@ -532,6 +532,36 @@ int basicTests(U32 seed, double compressibility)
             DISPLAYLEVEL(3, "%u bytes \n", (unsigned)cSizeLevelMax);
         }
 
+        DISPLAYLEVEL(3, "LZ4F_compressFrame_usingCDict, multiple linked blocks : ");
+        {   size_t cSizeContiguous;
+            size_t const inSize = dictSize * 3;
+            size_t const outCapacity = LZ4F_compressFrameBound(inSize, NULL);
+            LZ4F_preferences_t cParams;
+            memset(&cParams, 0, sizeof(cParams));
+            cParams.frameInfo.blockMode = LZ4F_blockLinked;
+            cParams.frameInfo.blockSizeID = LZ4F_max64KB;
+            CHECK_V(cSizeContiguous,
+                LZ4F_compressFrame_usingCDict(compressedBuffer, outCapacity,
+                                              CNBuffer, inSize,
+                                              cdict, &cParams) );
+            DISPLAYLEVEL(3, "%u bytes \n", (unsigned)cSizeContiguous);
+        }
+
+        DISPLAYLEVEL(3, "LZ4F_compressFrame_usingCDict, multiple independent blocks : ");
+        {   size_t cSizeIndep;
+            size_t const inSize = dictSize * 3;
+            size_t const outCapacity = LZ4F_compressFrameBound(inSize, NULL);
+            LZ4F_preferences_t cParams;
+            memset(&cParams, 0, sizeof(cParams));
+            cParams.frameInfo.blockMode = LZ4F_blockIndependent;
+            cParams.frameInfo.blockSizeID = LZ4F_max64KB;
+            CHECK_V(cSizeIndep,
+                LZ4F_compressFrame_usingCDict(compressedBuffer, outCapacity,
+                                              CNBuffer, inSize,
+                                              cdict, &cParams) );
+            DISPLAYLEVEL(3, "%u bytes \n", (unsigned)cSizeIndep);
+        }
+
         LZ4F_freeCDict(cdict);
     }
 
-- 
cgit v0.12


From 757497ae3db93a78d146ff573ae267f54e49c9b6 Mon Sep 17 00:00:00 2001
From: Yann Collet <cyan@fb.com>
Date: Thu, 10 Aug 2017 16:53:57 -0700
Subject: implemented lz4frame decompression API

---
 doc/lz4frame_manual.html |  10 ++---
 lib/lz4frame.c           | 106 +++++++++++++++++++++++------------------------
 lib/lz4frame.h           |  10 ++---
 lib/lz4frame_static.h    |  20 ++++++---
 tests/frametest.c        |  67 ++++++++++++++++++++++++++++--
 5 files changed, 141 insertions(+), 72 deletions(-)

diff --git a/doc/lz4frame_manual.html b/doc/lz4frame_manual.html
index 9593181..2a625a6 100644
--- a/doc/lz4frame_manual.html
+++ b/doc/lz4frame_manual.html
@@ -176,13 +176,13 @@ LZ4F_errorCode_t LZ4F_freeCompressionContext(LZ4F_cctx* cctx);
 </p></pre><BR>
 
 <pre><b>size_t LZ4F_compressEnd(LZ4F_cctx* cctx, void* dstBuffer, size_t dstCapacity, const LZ4F_compressOptions_t* cOptPtr);
-</b><p> To properly finish an LZ4 frame, invoke LZ4F_compressEnd().
- It will flush whatever data remained within `cctx` (like LZ4_flush())
- and properly finalize the frame, with an endMark and a checksum.
+</b><p>  To properly finish an LZ4 frame, invoke LZ4F_compressEnd().
+  It will flush whatever data remained within `cctx` (like LZ4_flush())
+  and properly finalize the frame, with an endMark and a checksum.
  `cOptPtr` is optional : NULL can be provided, in which case all options will be set to default.
  @return : number of bytes written into dstBuffer (necessarily >= 4 (endMark), or 8 if optional frame checksum is enabled)
            or an error code if it fails (which can be tested using LZ4F_isError())
- A successful call to LZ4F_compressEnd() makes `cctx` available again for another compression task.
+  A successful call to LZ4F_compressEnd() makes `cctx` available again for another compression task.
  
 </p></pre><BR>
 
@@ -190,7 +190,7 @@ LZ4F_errorCode_t LZ4F_freeCompressionContext(LZ4F_cctx* cctx);
 
 <pre><b>typedef struct {
   unsigned stableDst;    </b>/* pledge that at least 64KB+64Bytes of previously decompressed data remain unmodifed where it was decoded. This optimization skips storage operations in tmp buffers */<b>
-  unsigned reserved[3];
+  unsigned reserved[3];  </b>/* must be set to zero for forward compatibility */<b>
 } LZ4F_decompressOptions_t;
 </b></pre><BR>
 <pre><b>LZ4F_errorCode_t LZ4F_createDecompressionContext(LZ4F_dctx** dctxPtr, unsigned version);
diff --git a/lib/lz4frame.c b/lib/lz4frame.c
index fbccc9d..c27fc51 100644
--- a/lib/lz4frame.c
+++ b/lib/lz4frame.c
@@ -926,6 +926,8 @@ typedef enum {
 void LZ4F_resetDecompressionContext(LZ4F_dctx* dctx)
 {
     dctx->dStage = dstage_getHeader;
+    dctx->dict = NULL;
+    dctx->dictSize = 0;
 }
 
 
@@ -1101,19 +1103,6 @@ LZ4F_errorCode_t LZ4F_getFrameInfo(LZ4F_dctx* dctxPtr, LZ4F_frameInfo_t* frameIn
 }
 
 
-/* trivial redirector, for common prototype */
-static int LZ4F_decompress_safe (const char* src,
-                                 char* dst,
-                                 int compressedSize,
-                                 int dstCapacity,
-                                 const char* dictStart,
-                                 int dictSize)
-{
-    (void)dictStart; (void)dictSize;
-    return LZ4_decompress_safe (src, dst, compressedSize, dstCapacity);
-}
-
-
 static void LZ4F_updateDict(LZ4F_dctx* dctxPtr, const BYTE* dstPtr, size_t dstSize, const BYTE* dstPtr0, unsigned withinTmp)
 {
     if (dctxPtr->dictSize==0)
@@ -1174,21 +1163,22 @@ static void LZ4F_updateDict(LZ4F_dctx* dctxPtr, const BYTE* dstPtr, size_t dstSi
 
 
 /*! LZ4F_decompress() :
- * Call this function repetitively to regenerate data compressed within srcBuffer.
- * The function will attempt to decode up to *srcSizePtr bytes from srcBuffer, into dstBuffer of capacity *dstSizePtr.
+ *  Call this function repetitively to regenerate compressed data in srcBuffer.
+ *  The function will attempt to decode up to *srcSizePtr bytes from srcBuffer
+ *  into dstBuffer of capacity *dstSizePtr.
  *
- * The number of bytes regenerated into dstBuffer will be provided within *dstSizePtr (necessarily <= original value).
+ *  The number of bytes regenerated into dstBuffer will be provided within *dstSizePtr (necessarily <= original value).
  *
- * The number of bytes effectively read from srcBuffer will be provided within *srcSizePtr (necessarily <= original value).
- * If the number of bytes read is < number of bytes provided, then the decompression operation is not complete.
- * Remaining data will have to be presented again in a subsequent invocation.
+ *  The number of bytes effectively read from srcBuffer will be provided within *srcSizePtr (necessarily <= original value).
+ *  If number of bytes read is < number of bytes provided, then decompression operation is not complete.
+ *  Remaining data will have to be presented again in a subsequent invocation.
  *
- * The function result is an hint of the better srcSize to use for next call to LZ4F_decompress.
- * Basically, it's the size of the current (or remaining) compressed block + header of next block.
- * Respecting the hint provides some boost to performance, since it allows less buffer shuffling.
- * Note that this is just a hint, it's always possible to any srcSize value.
- * When a frame is fully decoded, @return will be 0.
- * If decompression failed, @return is an error code which can be tested using LZ4F_isError().
+ *  The function result is an hint of the better srcSize to use for next call to LZ4F_decompress.
+ *  Schematically, it's the size of the current (or remaining) compressed block + header of next block.
+ *  Respecting the hint provides a small boost to performance, since it allows less buffer shuffling.
+ *  Note that this is just a hint, and it's always possible to any srcSize value.
+ *  When a frame is fully decoded, @return will be 0.
+ *  If decompression failed, @return is an error code which can be tested using LZ4F_isError().
  */
 size_t LZ4F_decompress(LZ4F_dctx* dctxPtr,
                        void* dstBuffer, size_t* dstSizePtr,
@@ -1265,8 +1255,6 @@ size_t LZ4F_decompress(LZ4F_dctx* dctxPtr,
             }   }
             dctxPtr->tmpInSize = 0;
             dctxPtr->tmpInTarget = 0;
-            dctxPtr->dict = dctxPtr->tmpOutBuffer;
-            dctxPtr->dictSize = 0;
             dctxPtr->tmpOut = dctxPtr->tmpOutBuffer;
             dctxPtr->tmpOutStart = 0;
             dctxPtr->tmpOutSize = 0;
@@ -1381,15 +1369,8 @@ size_t LZ4F_decompress(LZ4F_dctx* dctxPtr,
             break;
 
         case dstage_decodeCBlock_intoDst:
-            {   int (*decoder)(const char*, char*, int, int, const char*, int);
-                int decodedSize;
-
-                if (dctxPtr->frameInfo.blockMode == LZ4F_blockLinked)
-                    decoder = LZ4_decompress_safe_usingDict;
-                else
-                    decoder = LZ4F_decompress_safe;
-
-                decodedSize = decoder((const char*)selectedIn, (char*)dstPtr,
+            {   int const decodedSize = LZ4_decompress_safe_usingDict(
+                        (const char*)selectedIn, (char*)dstPtr,
                         (int)dctxPtr->tmpInTarget, (int)dctxPtr->maxBlockSize,
                         (const char*)dctxPtr->dict, (int)dctxPtr->dictSize);
                 if (decodedSize < 0) return err0r(LZ4F_ERROR_GENERIC);   /* decompression failed */
@@ -1409,13 +1390,7 @@ size_t LZ4F_decompress(LZ4F_dctx* dctxPtr,
 
         case dstage_decodeCBlock_intoTmp:
             /* not enough place into dst : decode into tmpOut */
-            {   int (*decoder)(const char*, char*, int, int, const char*, int);
-                int decodedSize;
-
-                if (dctxPtr->frameInfo.blockMode == LZ4F_blockLinked)
-                    decoder = LZ4_decompress_safe_usingDict;
-                else
-                    decoder = LZ4F_decompress_safe;
+            {   int decodedSize;
 
                 /* ensure enough place for tmpOut */
                 if (dctxPtr->frameInfo.blockMode == LZ4F_blockLinked) {
@@ -1433,7 +1408,8 @@ size_t LZ4F_decompress(LZ4F_dctx* dctxPtr,
                 }
 
                 /* Decode */
-                decodedSize = decoder((const char*)selectedIn, (char*)dctxPtr->tmpOut,
+                decodedSize = LZ4_decompress_safe_usingDict(
+                        (const char*)selectedIn, (char*)dctxPtr->tmpOut,
                         (int)dctxPtr->tmpInTarget, (int)dctxPtr->maxBlockSize,
                         (const char*)dctxPtr->dict, (int)dctxPtr->dictSize);
                 if (decodedSize < 0)
@@ -1476,7 +1452,7 @@ size_t LZ4F_decompress(LZ4F_dctx* dctxPtr,
                     return err0r(LZ4F_ERROR_frameSize_wrong);   /* incorrect frame size decoded */
                 if (suffixSize == 0) {  /* frame completed */
                     nextSrcSizeHint = 0;
-                    dctxPtr->dStage = dstage_getHeader;
+                    LZ4F_resetDecompressionContext(dctxPtr);
                     doAnotherStage = 0;
                     break;
                 }
@@ -1510,7 +1486,7 @@ size_t LZ4F_decompress(LZ4F_dctx* dctxPtr,
                 U32 const resultCRC = XXH32_digest(&(dctxPtr->xxh));
                 if (readCRC != resultCRC) return err0r(LZ4F_ERROR_contentChecksum_invalid);
                 nextSrcSizeHint = 0;
-                dctxPtr->dStage = dstage_getHeader;
+                LZ4F_resetDecompressionContext(dctxPtr);
                 doAnotherStage = 0;
                 break;
             }
@@ -1530,7 +1506,8 @@ size_t LZ4F_decompress(LZ4F_dctx* dctxPtr,
         case dstage_storeSFrameSize:
             {
                 size_t sizeToCopy = dctxPtr->tmpInTarget - dctxPtr->tmpInSize;
-                if (sizeToCopy > (size_t)(srcEnd - srcPtr)) sizeToCopy = srcEnd - srcPtr;
+                if (sizeToCopy > (size_t)(srcEnd - srcPtr))
+                    sizeToCopy = srcEnd - srcPtr;
                 memcpy(dctxPtr->header + dctxPtr->tmpInSize, srcPtr, sizeToCopy);
                 srcPtr += sizeToCopy;
                 dctxPtr->tmpInSize += sizeToCopy;
@@ -1553,24 +1530,25 @@ size_t LZ4F_decompress(LZ4F_dctx* dctxPtr,
 
         case dstage_skipSkippable:
             {   size_t skipSize = dctxPtr->tmpInTarget;
-                if (skipSize > (size_t)(srcEnd-srcPtr)) skipSize = srcEnd-srcPtr;
+                if (skipSize > (size_t)(srcEnd-srcPtr))
+                    skipSize = srcEnd-srcPtr;
                 srcPtr += skipSize;
                 dctxPtr->tmpInTarget -= skipSize;
                 doAnotherStage = 0;
                 nextSrcSizeHint = dctxPtr->tmpInTarget;
                 if (nextSrcSizeHint) break;
-                dctxPtr->dStage = dstage_getHeader;
+                LZ4F_resetDecompressionContext(dctxPtr);
                 break;
             }
         }
     }
 
-    /* preserve dictionary within tmp if necessary */
+    /* preserve history within tmp if necessary */
     if ( (dctxPtr->frameInfo.blockMode==LZ4F_blockLinked)
-        &&(dctxPtr->dict != dctxPtr->tmpOutBuffer)
-        &&(!decompressOptionsPtr->stableDst)
-        &&((unsigned)(dctxPtr->dStage-1) < (unsigned)(dstage_getSuffix-1))
-        )
+      && (dctxPtr->dict != dctxPtr->tmpOutBuffer)
+      && (dctxPtr->dStage != dstage_getHeader)
+      && (!decompressOptionsPtr->stableDst)
+      && ((unsigned)(dctxPtr->dStage-1) < (unsigned)(dstage_getSuffix-1)) )
     {
         if (dctxPtr->dStage == dstage_flushOut) {
             size_t preserveSize = dctxPtr->tmpOut - dctxPtr->tmpOutBuffer;
@@ -1600,3 +1578,23 @@ size_t LZ4F_decompress(LZ4F_dctx* dctxPtr,
     *dstSizePtr = (dstPtr - dstStart);
     return nextSrcSizeHint;
 }
+
+/*! LZ4F_decompress_usingDict() :
+ *  Same as LZ4F_decompress(), using a predefined dictionary.
+ *  Dictionary is used "in place", without any preprocessing.
+ *  It must remain accessible throughout the entire frame decoding.
+ */
+size_t LZ4F_decompress_usingDict(LZ4F_dctx* dctxPtr,
+                       void* dstBuffer, size_t* dstSizePtr,
+                       const void* srcBuffer, size_t* srcSizePtr,
+                       const void* dict, size_t dictSize,
+                       const LZ4F_decompressOptions_t* decompressOptionsPtr)
+{
+    if (dctxPtr->dStage <= dstage_init) {
+        dctxPtr->dict = (const BYTE*)dict;
+        dctxPtr->dictSize = dictSize;
+    }
+    return LZ4F_decompress(dctxPtr, dstBuffer, dstSizePtr,
+                           srcBuffer, srcSizePtr,
+                           decompressOptionsPtr);
+}
diff --git a/lib/lz4frame.h b/lib/lz4frame.h
index dd76194..844255b 100644
--- a/lib/lz4frame.h
+++ b/lib/lz4frame.h
@@ -273,13 +273,13 @@ LZ4FLIB_API size_t LZ4F_compressUpdate(LZ4F_cctx* cctx, void* dstBuffer, size_t
 LZ4FLIB_API size_t LZ4F_flush(LZ4F_cctx* cctx, void* dstBuffer, size_t dstCapacity, const LZ4F_compressOptions_t* cOptPtr);
 
 /*! LZ4F_compressEnd() :
- * To properly finish an LZ4 frame, invoke LZ4F_compressEnd().
- * It will flush whatever data remained within `cctx` (like LZ4_flush())
- * and properly finalize the frame, with an endMark and a checksum.
+ *  To properly finish an LZ4 frame, invoke LZ4F_compressEnd().
+ *  It will flush whatever data remained within `cctx` (like LZ4_flush())
+ *  and properly finalize the frame, with an endMark and a checksum.
  * `cOptPtr` is optional : NULL can be provided, in which case all options will be set to default.
  * @return : number of bytes written into dstBuffer (necessarily >= 4 (endMark), or 8 if optional frame checksum is enabled)
  *           or an error code if it fails (which can be tested using LZ4F_isError())
- * A successful call to LZ4F_compressEnd() makes `cctx` available again for another compression task.
+ *  A successful call to LZ4F_compressEnd() makes `cctx` available again for another compression task.
  */
 LZ4FLIB_API size_t LZ4F_compressEnd(LZ4F_cctx* cctx, void* dstBuffer, size_t dstCapacity, const LZ4F_compressOptions_t* cOptPtr);
 
@@ -292,7 +292,7 @@ typedef LZ4F_dctx* LZ4F_decompressionContext_t;   /* compatibility with previous
 
 typedef struct {
   unsigned stableDst;    /* pledge that at least 64KB+64Bytes of previously decompressed data remain unmodifed where it was decoded. This optimization skips storage operations in tmp buffers */
-  unsigned reserved[3];
+  unsigned reserved[3];  /* must be set to zero for forward compatibility */
 } LZ4F_decompressOptions_t;
 
 
diff --git a/lib/lz4frame_static.h b/lib/lz4frame_static.h
index 5f22aed..b585b72 100644
--- a/lib/lz4frame_static.h
+++ b/lib/lz4frame_static.h
@@ -92,10 +92,11 @@ typedef struct LZ4F_CDict_s LZ4F_CDict;
  *  When compressing multiple messages / blocks with the same dictionary, it's recommended to load it just once.
  *  LZ4_createCDict() will create a digested dictionary, ready to start future compression operations without startup delay.
  *  LZ4_CDict can be created once and shared by multiple threads concurrently, since its usage is read-only.
- *  `dictBuffer` can be released after LZ4_CDict creation, since its content is copied within CDict */
+ * `dictBuffer` can be released after LZ4_CDict creation, since its content is copied within CDict */
 LZ4F_CDict* LZ4F_createCDict(const void* dictBuffer, size_t dictSize);
 void        LZ4F_freeCDict(LZ4F_CDict* CDict);
 
+
 /*! LZ4_compressFrame_usingCDict() :
  *  Compress an entire srcBuffer into a valid LZ4 frame using a digested Dictionary.
  *  If cdict==NULL, compress without a dictionary.
@@ -104,8 +105,7 @@ void        LZ4F_freeCDict(LZ4F_CDict* CDict);
  *  The LZ4F_preferences_t structure is optional : you may provide NULL as argument,
  *  but it's not recommended, as it's the only way to provide dictID in the frame header.
  * @return : number of bytes written into dstBuffer.
- *           or an error code if it fails (can be tested using LZ4F_isError())
- */
+ *           or an error code if it fails (can be tested using LZ4F_isError()) */
 size_t LZ4F_compressFrame_usingCDict(void* dst, size_t dstCapacity,
                                const void* src, size_t srcSize,
                                const LZ4F_CDict* cdict,
@@ -118,14 +118,24 @@ size_t LZ4F_compressFrame_usingCDict(void* dst, size_t dstCapacity,
  * `prefsPtr` is optional : you may provide NULL as argument,
  *  however, it's the only way to provide dictID in the frame header.
  * @return : number of bytes written into dstBuffer for the header,
- *           or an error code (which can be tested using LZ4F_isError())
- */
+ *           or an error code (which can be tested using LZ4F_isError()) */
 size_t LZ4F_compressBegin_usingCDict(LZ4F_cctx* cctx,
                                      void* dstBuffer, size_t dstCapacity,
                                      const LZ4F_CDict* cdict,
                                      const LZ4F_preferences_t* prefsPtr);
 
 
+/*! LZ4F_decompress_usingDict() :
+ *  Same as LZ4F_decompress(), using a predefined dictionary.
+ *  Dictionary is used "in place", without any preprocessing.
+ *  It must remain accessible throughout the entire frame decoding. */
+size_t LZ4F_decompress_usingDict(LZ4F_dctx* dctxPtr,
+                       void* dstBuffer, size_t* dstSizePtr,
+                       const void* srcBuffer, size_t* srcSizePtr,
+                       const void* dict, size_t dictSize,
+                       const LZ4F_decompressOptions_t* decompressOptionsPtr);
+
+
 #if defined (__cplusplus)
 }
 #endif
diff --git a/tests/frametest.c b/tests/frametest.c
index a30089f..d0665c5 100644
--- a/tests/frametest.c
+++ b/tests/frametest.c
@@ -505,8 +505,28 @@ int basicTests(U32 seed, double compressibility)
                 LZ4F_compressFrame_usingCDict(compressedBuffer, dstCapacity,
                                               CNBuffer, dictSize,
                                               cdict, NULL) );
-        DISPLAYLEVEL(3, "%u bytes \n", (unsigned)cSizeWithDict);
+        DISPLAYLEVEL(3, "compressed %u bytes into %u bytes \n",
+                        (unsigned)dictSize, (unsigned)cSizeWithDict);
         if (cSizeWithDict >= cSizeNoDict) goto _output_error;  /* must be more efficient */
+        crcOrig = XXH64(CNBuffer, dictSize, 0);
+
+        DISPLAYLEVEL(3, "LZ4F_decompress_usingDict : ");
+        {   LZ4F_dctx* dctx;
+            size_t decodedSize = COMPRESSIBLE_NOISE_LENGTH;
+            size_t compressedSize = cSizeWithDict;
+            CHECK( LZ4F_createDecompressionContext(&dctx, LZ4F_VERSION) );
+            CHECK( LZ4F_decompress_usingDict(dctx,
+                                        decodedBuffer, &decodedSize,
+                                        compressedBuffer, &compressedSize,
+                                        CNBuffer, dictSize,
+                                        NULL) );
+            if (compressedSize != cSizeWithDict) goto _output_error;
+            if (decodedSize != dictSize) goto _output_error;
+            { U64 const crcDest = XXH64(decodedBuffer, decodedSize, 0);
+              if (crcDest != crcOrig) goto _output_error; }
+            DISPLAYLEVEL(3, "Regenerated %u bytes \n", (U32)decodedSize);
+            CHECK( LZ4F_freeDecompressionContext(dctx) );
+        }
 
         DISPLAYLEVEL(3, "LZ4F_compressFrame_usingCDict, with dict, negative level : ");
         {   size_t cSizeLevelMax;
@@ -544,9 +564,30 @@ int basicTests(U32 seed, double compressibility)
                 LZ4F_compressFrame_usingCDict(compressedBuffer, outCapacity,
                                               CNBuffer, inSize,
                                               cdict, &cParams) );
-            DISPLAYLEVEL(3, "%u bytes \n", (unsigned)cSizeContiguous);
+            DISPLAYLEVEL(3, "compressed %u bytes into %u bytes \n",
+                        (unsigned)inSize, (unsigned)cSizeContiguous);
+
+            DISPLAYLEVEL(3, "LZ4F_decompress_usingDict on multiple linked blocks : ");
+            {   LZ4F_dctx* dctx;
+                size_t decodedSize = COMPRESSIBLE_NOISE_LENGTH;
+                size_t compressedSize = cSizeContiguous;
+                CHECK( LZ4F_createDecompressionContext(&dctx, LZ4F_VERSION) );
+                CHECK( LZ4F_decompress_usingDict(dctx,
+                                            decodedBuffer, &decodedSize,
+                                            compressedBuffer, &compressedSize,
+                                            CNBuffer, dictSize,
+                                            NULL) );
+                if (compressedSize != cSizeContiguous) goto _output_error;
+                if (decodedSize != inSize) goto _output_error;
+                crcOrig = XXH64(CNBuffer, inSize, 0);
+                { U64 const crcDest = XXH64(decodedBuffer, decodedSize, 0);
+                  if (crcDest != crcOrig) goto _output_error; }
+                DISPLAYLEVEL(3, "Regenerated %u bytes \n", (U32)decodedSize);
+                CHECK( LZ4F_freeDecompressionContext(dctx) );
+            }
         }
 
+
         DISPLAYLEVEL(3, "LZ4F_compressFrame_usingCDict, multiple independent blocks : ");
         {   size_t cSizeIndep;
             size_t const inSize = dictSize * 3;
@@ -559,7 +600,27 @@ int basicTests(U32 seed, double compressibility)
                 LZ4F_compressFrame_usingCDict(compressedBuffer, outCapacity,
                                               CNBuffer, inSize,
                                               cdict, &cParams) );
-            DISPLAYLEVEL(3, "%u bytes \n", (unsigned)cSizeIndep);
+            DISPLAYLEVEL(3, "compressed %u bytes into %u bytes \n",
+                        (unsigned)inSize, (unsigned)cSizeIndep);
+
+            DISPLAYLEVEL(3, "LZ4F_decompress_usingDict on multiple independent blocks : ");
+            {   LZ4F_dctx* dctx;
+                size_t decodedSize = COMPRESSIBLE_NOISE_LENGTH;
+                size_t compressedSize = cSizeIndep;
+                CHECK( LZ4F_createDecompressionContext(&dctx, LZ4F_VERSION) );
+                CHECK( LZ4F_decompress_usingDict(dctx,
+                                            decodedBuffer, &decodedSize,
+                                            compressedBuffer, &compressedSize,
+                                            CNBuffer, dictSize,
+                                            NULL) );
+                if (compressedSize != cSizeIndep) goto _output_error;
+                if (decodedSize != inSize) goto _output_error;
+                crcOrig = XXH64(CNBuffer, inSize, 0);
+                { U64 const crcDest = XXH64(decodedBuffer, decodedSize, 0);
+                  if (crcDest != crcOrig) goto _output_error; }
+                DISPLAYLEVEL(3, "Regenerated %u bytes \n", (U32)decodedSize);
+                CHECK( LZ4F_freeDecompressionContext(dctx) );
+            }
         }
 
         LZ4F_freeCDict(cdict);
-- 
cgit v0.12


From 77f99d2922a82bd3187dd7086a8b9dee06bbaed6 Mon Sep 17 00:00:00 2001
From: Yann Collet <cyan@fb.com>
Date: Fri, 11 Aug 2017 17:46:52 -0700
Subject: restored block checksum capability at lz4frame API level

---
 NEWS                     |   1 +
 doc/lz4frame_manual.html |  25 +-
 examples/frameCompress.c |   6 +-
 lib/lz4frame.c           | 699 ++++++++++++++++++++++++++---------------------
 lib/lz4frame.h           |  25 +-
 lib/lz4frame_static.h    |   2 +-
 tests/frametest.c        |  28 +-
 7 files changed, 445 insertions(+), 341 deletions(-)

diff --git a/NEWS b/NEWS
index d10c48f..63d53a6 100644
--- a/NEWS
+++ b/NEWS
@@ -4,6 +4,7 @@ cli : added GNU separator -- specifying that all following arguments are files
 API : added LZ4_compress_HC_destSize(), by Oleg (@remittor)
 API : added LZ4F_resetDecompressionContext()
 API : lz4frame : negative compression levels trigger fast acceleration, request by Lawrence Chan
+API : lz4frame : can control block checksum and dictionary ID
 API : fix : expose obsolete decoding functions, reported by Chen Yufei
 build : fix : static lib installation, by Ido Rosen
 build : dragonFlyBSD, OpenBSD, NetBSD supported
diff --git a/doc/lz4frame_manual.html b/doc/lz4frame_manual.html
index 2a625a6..7529f6e 100644
--- a/doc/lz4frame_manual.html
+++ b/doc/lz4frame_manual.html
@@ -63,6 +63,11 @@
 } LZ4F_contentChecksum_t;
 </b></pre><BR>
 <pre><b>typedef enum {
+    LZ4F_noBlockChecksum=0,
+    LZ4F_blockChecksumEnabled
+} LZ4F_blockChecksum_t;
+</b></pre><BR>
+<pre><b>typedef enum {
     LZ4F_frame=0,
     LZ4F_skippableFrame
     LZ4F_OBSOLETE_ENUM(skippableFrame)
@@ -70,16 +75,16 @@
 </b></pre><BR>
 <pre><b>typedef struct {
   LZ4F_blockSizeID_t     blockSizeID;          </b>/* max64KB, max256KB, max1MB, max4MB ; 0 == default */<b>
-  LZ4F_blockMode_t       blockMode;            </b>/* blockLinked, blockIndependent ; 0 == default */<b>
-  LZ4F_contentChecksum_t contentChecksumFlag;  </b>/* noContentChecksum, contentChecksumEnabled ; 0 == default  */<b>
-  LZ4F_frameType_t       frameType;            </b>/* LZ4F_frame, skippableFrame ; 0 == default */<b>
+  LZ4F_blockMode_t       blockMode;            </b>/* LZ4F_blockLinked, LZ4F_blockIndependent ; 0 == default */<b>
+  LZ4F_contentChecksum_t contentChecksumFlag;  </b>/* if enabled, frame is terminated with a 32-bits checksum of decompressed data ; 0 == disabled (default)  */<b>
+  LZ4F_frameType_t       frameType;            </b>/* read-only field : LZ4F_frame or LZ4F_skippableFrame */<b>
   unsigned long long     contentSize;          </b>/* Size of uncompressed content ; 0 == unknown */<b>
   unsigned               dictID;               </b>/* Dictionary ID, sent by the compressor to help decoder select the correct dictionary; 0 == no dictID provided */<b>
-  unsigned               reserved[1];          </b>/* must be zero for forward compatibility */<b>
+  LZ4F_blockChecksum_t   blockChecksumFlag;    </b>/* if enabled, each block is followed by a checksum of block's compressed data ; 0 == disabled (default)  */<b>
 } LZ4F_frameInfo_t;
-</b><p> makes it possible to supply detailed frame parameters to the stream interface.
- It's not required to set all fields, as long as the structure was initially memset() to zero.
- All reserved fields must be set to zero. 
+</b><p>  makes it possible to set or read frame parameters.
+  It's not required to set all fields, as long as the structure was initially memset() to zero.
+  For all fields, 0 sets it to default value 
 </p></pre><BR>
 
 <pre><b>typedef struct {
@@ -88,9 +93,9 @@
   unsigned autoFlush;              </b>/* 1 == always flush, to reduce usage of internal buffers */<b>
   unsigned reserved[4];            </b>/* must be zero for forward compatibility */<b>
 } LZ4F_preferences_t;
-</b><p> makes it possible to supply detailed compression parameters to the stream interface.
- It's not required to set all fields, as long as the structure was initially memset() to zero.
- All reserved fields must be set to zero. 
+</b><p>  makes it possible to supply detailed compression parameters to the stream interface.
+  It's not required to set all fields, as long as the structure was initially memset() to zero.
+  All reserved fields must be set to zero. 
 </p></pre><BR>
 
 <a name="Chapter5"></a><h2>Simple compression function</h2><pre></pre>
diff --git a/examples/frameCompress.c b/examples/frameCompress.c
index 0a42fe3..8712725 100644
--- a/examples/frameCompress.c
+++ b/examples/frameCompress.c
@@ -14,7 +14,7 @@
 
 static const LZ4F_preferences_t lz4_preferences = {
     { LZ4F_max256KB, LZ4F_blockLinked, LZ4F_noContentChecksum, LZ4F_frame,
-      0 /* content size unknown */, 0 /* no dictID */ , { 0 } /* reserved */ },
+      0 /* content size unknown */, 0 /* no dictID */ , LZ4F_noBlockChecksum },
     0,   /* compression level */
     0,   /* autoflush */
     { 0, 0, 0, 0 },  /* reserved, must be set to 0 */
@@ -266,7 +266,7 @@ int main(int argc, const char **argv) {
         ret = compress_file(inpFp, outFp, &sizeIn, &sizeOut);
         if (ret) {
             printf("compress : failed with code %zu\n", ret);
-            return ret;
+            return (int)ret;
         }
         printf("%s: %zu → %zu bytes, %.1f%%\n",
             inpFilename, sizeIn, sizeOut,
@@ -286,7 +286,7 @@ int main(int argc, const char **argv) {
         ret = decompress_file(inpFp, outFp);
         if (ret) {
             printf("decompress : failed with code %zu\n", ret);
-            return ret;
+            return (int)ret;
         }
         printf("decompress : done\n");
 
diff --git a/lib/lz4frame.c b/lib/lz4frame.c
index c27fc51..e613901 100644
--- a/lib/lz4frame.c
+++ b/lib/lz4frame.c
@@ -68,7 +68,7 @@ You can contact the author at :
 
 
 /*-************************************
-*  Common Utils
+*  Debug
 **************************************/
 #define LZ4_STATIC_ASSERT(c)    { enum { LZ4_static_assert = 1/(int)(!!(c)) }; }   /* use only *after* variable declarations */
 
@@ -260,11 +260,11 @@ static LZ4F_blockSizeID_t LZ4F_optimalBSID(const LZ4F_blockSizeID_t requestedBSI
     return requestedBSID;
 }
 
-/* LZ4F_compressBound_internal() :
- * Provides dstCapacity given a srcSize to guarantee operation success in worst case situations.
- * prefsPtr is optional : if NULL is provided, preferences will be set to cover worst case scenario.
- * Result is always the same for a srcSize and prefsPtr, so it can be relied upon to size reusable buffers.
- * When srcSize==0, LZ4F_compressBound() provides an upper bound for LZ4F_flush() and LZ4F_compressEnd() operations.
+/*! LZ4F_compressBound_internal() :
+ *  Provides dstCapacity given a srcSize to guarantee operation success in worst case situations.
+ *  prefsPtr is optional : if NULL is provided, preferences will be set to cover worst case scenario.
+ * @return is always the same for a srcSize and prefsPtr, so it can be relied upon to size reusable buffers.
+ *  When srcSize==0, LZ4F_compressBound() provides an upper bound for LZ4F_flush() and LZ4F_compressEnd() operations.
  */
 static size_t LZ4F_compressBound_internal(size_t srcSize,
                                     const LZ4F_preferences_t* preferencesPtr,
@@ -275,8 +275,8 @@ static size_t LZ4F_compressBound_internal(size_t srcSize,
     prefsNull.frameInfo.contentChecksumFlag = LZ4F_contentChecksumEnabled;   /* worst case */
     {   const LZ4F_preferences_t* const prefsPtr = (preferencesPtr==NULL) ? &prefsNull : preferencesPtr;
         U32 const flush = prefsPtr->autoFlush | (srcSize==0);
-        LZ4F_blockSizeID_t const bid = prefsPtr->frameInfo.blockSizeID;
-        size_t const blockSize = LZ4F_getBlockSize(bid);
+        LZ4F_blockSizeID_t const blockID = prefsPtr->frameInfo.blockSizeID;
+        size_t const blockSize = LZ4F_getBlockSize(blockID);
         size_t const maxBuffered = blockSize - 1;
         size_t const bufferedSize = MIN(alreadyBuffered, maxBuffered);
         size_t const maxSrcSize = srcSize + bufferedSize;
@@ -285,10 +285,12 @@ static size_t LZ4F_compressBound_internal(size_t srcSize,
         size_t const lastBlockSize = flush ? partialBlockSize : 0;
         unsigned const nbBlocks = nbFullBlocks + (lastBlockSize>0);
 
-        size_t const blockHeaderSize = 4;   /* default, without block CRC option (which cannot be generated with current API) */
+        size_t const blockHeaderSize = 4;
+        size_t const blockCRCSize = 4 * prefsPtr->frameInfo.blockChecksumFlag;
         size_t const frameEnd = 4 + (prefsPtr->frameInfo.contentChecksumFlag*4);
 
-        return (blockHeaderSize * nbBlocks) + (blockSize * nbFullBlocks) + lastBlockSize + frameEnd;;
+        return ((blockHeaderSize + blockCRCSize) * nbBlocks) +
+               (blockSize * nbFullBlocks) + lastBlockSize + frameEnd;
     }
 }
 
@@ -400,11 +402,11 @@ struct LZ4F_CDict_s {
     LZ4_streamHC_t* HCCtx;
 }; /* typedef'd to LZ4F_CDict within lz4frame_static.h */
 
-/*! LZ4_createCDict() :
+/*! LZ4F_createCDict() :
  *  When compressing multiple messages / blocks with the same dictionary, it's recommended to load it just once.
- *  LZ4_createCDict() will create a digested dictionary, ready to start future compression operations without startup delay.
- *  LZ4_CDict can be created once and shared by multiple threads concurrently, since its usage is read-only.
- * `dictBuffer` can be released after LZ4_CDict creation, since its content is copied within CDict
+ *  LZ4F_createCDict() will create a digested dictionary, ready to start future compression operations without startup delay.
+ *  LZ4F_CDict can be created once and shared by multiple threads concurrently, since its usage is read-only.
+ * `dictBuffer` can be released after LZ4F_CDict creation, since its content is copied within CDict
  * @return : digested dictionary for compression, or NULL if failed */
 LZ4F_CDict* LZ4F_createCDict(const void* dictBuffer, size_t dictSize)
 {
@@ -559,10 +561,11 @@ size_t LZ4F_compressBegin_usingCDict(LZ4F_cctx* cctxPtr,
 
     /* FLG Byte */
     *dstPtr++ = (BYTE)(((1 & _2BITS) << 6)    /* Version('01') */
-        + ((cctxPtr->prefs.frameInfo.blockMode & _1BIT ) << 5)  /* Block mode */
-        + ((cctxPtr->prefs.frameInfo.contentSize > 0) << 3)     /* Frame content size */
-        + ((cctxPtr->prefs.frameInfo.contentChecksumFlag & _1BIT ) << 2)   /* Frame checksum */
-        +  (cctxPtr->prefs.frameInfo.dictID > 0) );   /* Dictionary ID */
+        + ((cctxPtr->prefs.frameInfo.blockMode & _1BIT ) << 5)
+        + ((cctxPtr->prefs.frameInfo.blockChecksumFlag & _1BIT ) << 4)
+        + ((cctxPtr->prefs.frameInfo.contentSize > 0) << 3)
+        + ((cctxPtr->prefs.frameInfo.contentChecksumFlag & _1BIT ) << 2)
+        +  (cctxPtr->prefs.frameInfo.dictID > 0) );
     /* BD Byte */
     *dstPtr++ = (BYTE)((cctxPtr->prefs.frameInfo.blockSizeID & _3BITS) << 4);
     /* Optional Frame content size field */
@@ -614,9 +617,14 @@ size_t LZ4F_compressBound(size_t srcSize, const LZ4F_preferences_t* preferencesP
 
 typedef int (*compressFunc_t)(void* ctx, const char* src, char* dst, int srcSize, int dstSize, int level, const LZ4F_CDict* cdict);
 
-static size_t LZ4F_makeBlock(void* dst, const void* src, size_t srcSize, compressFunc_t compress, void* lz4ctx, int level, const LZ4F_CDict* cdict)
+
+/*! LZ4F_makeBlock():
+ *  compress a single block, add header and checksum
+ *  assumption : dst buffer capacity is >= srcSize */
+static size_t LZ4F_makeBlock(void* dst, const void* src, size_t srcSize,
+                             compressFunc_t compress, void* lz4ctx, int level,
+                             const LZ4F_CDict* cdict, LZ4F_blockChecksum_t crcFlag)
 {
-    /* compress a single block */
     BYTE* const cSizePtr = (BYTE*)dst;
     U32 cSize = (U32)compress(lz4ctx, (const char*)src, (char*)(cSizePtr+4),
                                       (int)(srcSize), (int)(srcSize-1),
@@ -627,7 +635,11 @@ static size_t LZ4F_makeBlock(void* dst, const void* src, size_t srcSize, compres
         LZ4F_writeLE32(cSizePtr, cSize | LZ4F_BLOCKUNCOMPRESSED_FLAG);
         memcpy(cSizePtr+4, src, srcSize);
     }
-    return cSize + 4;
+    if (crcFlag) {
+        U32 const crc32 = XXH32(cSizePtr+4, cSize, 0);  /* checksum of compressed data */
+        LZ4F_writeLE32(cSizePtr+4+cSize, crc32);
+    }
+    return 4 + cSize + ((U32)crcFlag)*4;
 }
 
 
@@ -690,7 +702,10 @@ typedef enum { notDone, fromTmpBuffer, fromSrcBuffer } LZ4F_lastBlockStatus;
  * @return : the number of bytes written into dstBuffer. It can be zero, meaning input data was just buffered.
  *           or an error code if it fails (which can be tested using LZ4F_isError())
  */
-size_t LZ4F_compressUpdate(LZ4F_cctx* cctxPtr, void* dstBuffer, size_t dstCapacity, const void* srcBuffer, size_t srcSize, const LZ4F_compressOptions_t* compressOptionsPtr)
+size_t LZ4F_compressUpdate(LZ4F_cctx* cctxPtr,
+                           void* dstBuffer, size_t dstCapacity,
+                     const void* srcBuffer, size_t srcSize,
+                     const LZ4F_compressOptions_t* compressOptionsPtr)
 {
     LZ4F_compressOptions_t cOptionsNull;
     size_t const blockSize = cctxPtr->maxBlockSize;
@@ -722,7 +737,9 @@ size_t LZ4F_compressUpdate(LZ4F_cctx* cctxPtr, void* dstBuffer, size_t dstCapaci
             memcpy(cctxPtr->tmpIn + cctxPtr->tmpInSize, srcBuffer, sizeToCopy);
             srcPtr += sizeToCopy;
 
-            dstPtr += LZ4F_makeBlock(dstPtr, cctxPtr->tmpIn, blockSize, compress, cctxPtr->lz4CtxPtr, cctxPtr->prefs.compressionLevel, cctxPtr->cdict);
+            dstPtr += LZ4F_makeBlock(dstPtr, cctxPtr->tmpIn, blockSize,
+                                     compress, cctxPtr->lz4CtxPtr, cctxPtr->prefs.compressionLevel,
+                                     cctxPtr->cdict, cctxPtr->prefs.frameInfo.blockChecksumFlag);
 
             if (cctxPtr->prefs.frameInfo.blockMode==LZ4F_blockLinked) cctxPtr->tmpIn += blockSize;
             cctxPtr->tmpInSize = 0;
@@ -732,14 +749,18 @@ size_t LZ4F_compressUpdate(LZ4F_cctx* cctxPtr, void* dstBuffer, size_t dstCapaci
     while ((size_t)(srcEnd - srcPtr) >= blockSize) {
         /* compress full blocks */
         lastBlockCompressed = fromSrcBuffer;
-        dstPtr += LZ4F_makeBlock(dstPtr, srcPtr, blockSize, compress, cctxPtr->lz4CtxPtr, cctxPtr->prefs.compressionLevel, cctxPtr->cdict);
+        dstPtr += LZ4F_makeBlock(dstPtr, srcPtr, blockSize,
+                                 compress, cctxPtr->lz4CtxPtr, cctxPtr->prefs.compressionLevel,
+                                 cctxPtr->cdict, cctxPtr->prefs.frameInfo.blockChecksumFlag);
         srcPtr += blockSize;
     }
 
     if ((cctxPtr->prefs.autoFlush) && (srcPtr < srcEnd)) {
         /* compress remaining input < blockSize */
         lastBlockCompressed = fromSrcBuffer;
-        dstPtr += LZ4F_makeBlock(dstPtr, srcPtr, srcEnd - srcPtr, compress, cctxPtr->lz4CtxPtr, cctxPtr->prefs.compressionLevel, cctxPtr->cdict);
+        dstPtr += LZ4F_makeBlock(dstPtr, srcPtr, srcEnd - srcPtr,
+                                 compress, cctxPtr->lz4CtxPtr, cctxPtr->prefs.compressionLevel,
+                                 cctxPtr->cdict, cctxPtr->prefs.frameInfo.blockChecksumFlag);
         srcPtr  = srcEnd;
     }
 
@@ -801,7 +822,9 @@ size_t LZ4F_flush(LZ4F_cctx* cctxPtr, void* dstBuffer, size_t dstCapacity, const
     compress = LZ4F_selectCompression(cctxPtr->prefs.frameInfo.blockMode, cctxPtr->prefs.compressionLevel);
 
     /* compress tmp buffer */
-    dstPtr += LZ4F_makeBlock(dstPtr, cctxPtr->tmpIn, cctxPtr->tmpInSize, compress, cctxPtr->lz4CtxPtr, cctxPtr->prefs.compressionLevel, cctxPtr->cdict);
+    dstPtr += LZ4F_makeBlock(dstPtr, cctxPtr->tmpIn, cctxPtr->tmpInSize,
+                             compress, cctxPtr->lz4CtxPtr, cctxPtr->prefs.compressionLevel,
+                             cctxPtr->cdict, cctxPtr->prefs.frameInfo.blockChecksumFlag);
     if (cctxPtr->prefs.frameInfo.blockMode==LZ4F_blockLinked) cctxPtr->tmpIn += cctxPtr->tmpInSize;
     cctxPtr->tmpInSize = 0;
 
@@ -858,10 +881,23 @@ size_t LZ4F_compressEnd(LZ4F_cctx* cctxPtr, void* dstBuffer, size_t dstMaxSize,
 *   Frame Decompression
 *****************************************************/
 
+typedef enum {
+    dstage_getFrameHeader=0, dstage_storeFrameHeader,
+    dstage_init,
+    dstage_getBlockHeader, dstage_storeBlockHeader,
+    dstage_copyDirect, dstage_getBlockChecksum,
+    dstage_getCBlock, dstage_storeCBlock,
+    dstage_decodeCBlock, dstage_decodeCBlock_intoDst,
+    dstage_decodeCBlock_intoTmp, dstage_flushOut,
+    dstage_getSuffix, dstage_storeSuffix,
+    dstage_getSFrameSize, dstage_storeSFrameSize,
+    dstage_skipSkippable
+} dStage_t;
+
 struct LZ4F_dctx_s {
     LZ4F_frameInfo_t frameInfo;
     U32    version;
-    U32    dStage;
+    dStage_t dStage;
     U64    frameRemainingSize;
     size_t maxBlockSize;
     size_t maxBufferSize;
@@ -869,40 +905,41 @@ struct LZ4F_dctx_s {
     size_t tmpInSize;
     size_t tmpInTarget;
     BYTE*  tmpOutBuffer;
-    const BYTE*  dict;
+    const BYTE* dict;
     size_t dictSize;
     BYTE*  tmpOut;
     size_t tmpOutSize;
     size_t tmpOutStart;
     XXH32_state_t xxh;
+    XXH32_state_t blockChecksum;
     BYTE   header[16];
 };  /* typedef'd to LZ4F_dctx in lz4frame.h */
 
 
 /*! LZ4F_createDecompressionContext() :
- *   Create a decompressionContext object, which will track all decompression operations.
- *   Provides a pointer to a fully allocated and initialized LZ4F_decompressionContext object.
- *   Object can later be released using LZ4F_freeDecompressionContext().
- *   @return : if != 0, there was an error during context creation.
+ *  Create a decompressionContext object, which will track all decompression operations.
+ *  Provides a pointer to a fully allocated and initialized LZ4F_decompressionContext object.
+ *  Object can later be released using LZ4F_freeDecompressionContext().
+ * @return : if != 0, there was an error during context creation.
  */
 LZ4F_errorCode_t LZ4F_createDecompressionContext(LZ4F_dctx** LZ4F_decompressionContextPtr, unsigned versionNumber)
 {
-    LZ4F_dctx* const dctxPtr = (LZ4F_dctx*)ALLOCATOR(sizeof(LZ4F_dctx));
-    if (dctxPtr==NULL) return err0r(LZ4F_ERROR_GENERIC);
+    LZ4F_dctx* const dctx = (LZ4F_dctx*)ALLOCATOR(sizeof(LZ4F_dctx));
+    if (dctx==NULL) return err0r(LZ4F_ERROR_GENERIC);
 
-    dctxPtr->version = versionNumber;
-    *LZ4F_decompressionContextPtr = dctxPtr;
+    dctx->version = versionNumber;
+    *LZ4F_decompressionContextPtr = dctx;
     return LZ4F_OK_NoError;
 }
 
-LZ4F_errorCode_t LZ4F_freeDecompressionContext(LZ4F_dctx* dctxPtr)
+LZ4F_errorCode_t LZ4F_freeDecompressionContext(LZ4F_dctx* dctx)
 {
     LZ4F_errorCode_t result = LZ4F_OK_NoError;
-    if (dctxPtr != NULL) {   /* can accept NULL input, like free() */
-      result = (LZ4F_errorCode_t)dctxPtr->dStage;
-      FREEMEM(dctxPtr->tmpIn);
-      FREEMEM(dctxPtr->tmpOutBuffer);
-      FREEMEM(dctxPtr);
+    if (dctx != NULL) {   /* can accept NULL input, like free() */
+      result = (LZ4F_errorCode_t)dctx->dStage;
+      FREEMEM(dctx->tmpIn);
+      FREEMEM(dctx->tmpOutBuffer);
+      FREEMEM(dctx);
     }
     return result;
 }
@@ -910,22 +947,9 @@ LZ4F_errorCode_t LZ4F_freeDecompressionContext(LZ4F_dctx* dctxPtr)
 
 /*==---   Streaming Decompression operations   ---==*/
 
-typedef enum {
-    dstage_getHeader=0, dstage_storeHeader,
-    dstage_init,
-    dstage_getCBlockSize, dstage_storeCBlockSize,
-    dstage_copyDirect,
-    dstage_getCBlock, dstage_storeCBlock,
-    dstage_decodeCBlock, dstage_decodeCBlock_intoDst,
-    dstage_decodeCBlock_intoTmp, dstage_flushOut,
-    dstage_getSuffix, dstage_storeSuffix,
-    dstage_getSFrameSize, dstage_storeSFrameSize,
-    dstage_skipSkippable
-} dStage_t;
-
 void LZ4F_resetDecompressionContext(LZ4F_dctx* dctx)
 {
-    dctx->dStage = dstage_getHeader;
+    dctx->dStage = dstage_getFrameHeader;
     dctx->dict = NULL;
     dctx->dictSize = 0;
 }
@@ -959,31 +983,31 @@ static size_t LZ4F_headerSize(const void* src, size_t srcSize)
 /*! LZ4F_decodeHeader() :
  *  input   : `src` points at the **beginning of the frame**
  *  output  : set internal values of dctx, such as
- *            dctxPtr->frameInfo and dctxPtr->dStage.
+ *            dctx->frameInfo and dctx->dStage.
  *            Also allocates internal buffers.
  *  @return : nb Bytes read from src (necessarily <= srcSize)
  *            or an error code (testable with LZ4F_isError())
  */
-static size_t LZ4F_decodeHeader(LZ4F_dctx* dctxPtr, const void* src, size_t srcSize)
+static size_t LZ4F_decodeHeader(LZ4F_dctx* dctx, const void* src, size_t srcSize)
 {
-    unsigned blockMode, contentSizeFlag, contentChecksumFlag, dictIDFlag, blockSizeID;
+    unsigned blockMode, blockChecksumFlag, contentSizeFlag, contentChecksumFlag, dictIDFlag, blockSizeID;
     size_t frameHeaderSize;
     const BYTE* srcPtr = (const BYTE*)src;
 
     /* need to decode header to get frameInfo */
     if (srcSize < minFHSize) return err0r(LZ4F_ERROR_frameHeader_incomplete);   /* minimal frame header size */
-    memset(&(dctxPtr->frameInfo), 0, sizeof(dctxPtr->frameInfo));
+    memset(&(dctx->frameInfo), 0, sizeof(dctx->frameInfo));
 
     /* special case : skippable frames */
     if ((LZ4F_readLE32(srcPtr) & 0xFFFFFFF0U) == LZ4F_MAGIC_SKIPPABLE_START) {
-        dctxPtr->frameInfo.frameType = LZ4F_skippableFrame;
-        if (src == (void*)(dctxPtr->header)) {
-            dctxPtr->tmpInSize = srcSize;
-            dctxPtr->tmpInTarget = 8;
-            dctxPtr->dStage = dstage_storeSFrameSize;
+        dctx->frameInfo.frameType = LZ4F_skippableFrame;
+        if (src == (void*)(dctx->header)) {
+            dctx->tmpInSize = srcSize;
+            dctx->tmpInTarget = 8;
+            dctx->dStage = dstage_storeSFrameSize;
             return srcSize;
         } else {
-            dctxPtr->dStage = dstage_getSFrameSize;
+            dctx->dStage = dstage_getSFrameSize;
             return 4;
         }
     }
@@ -991,20 +1015,19 @@ static size_t LZ4F_decodeHeader(LZ4F_dctx* dctxPtr, const void* src, size_t srcS
     /* control magic number */
     if (LZ4F_readLE32(srcPtr) != LZ4F_MAGICNUMBER)
         return err0r(LZ4F_ERROR_frameType_unknown);
-    dctxPtr->frameInfo.frameType = LZ4F_frame;
+    dctx->frameInfo.frameType = LZ4F_frame;
 
     /* Flags */
     {   U32 const FLG = srcPtr[4];
         U32 const version = (FLG>>6) & _2BITS;
-        U32 const blockChecksumFlag = (FLG>>4) & _1BIT;
+        blockChecksumFlag = (FLG>>4) & _1BIT;
         blockMode = (FLG>>5) & _1BIT;
         contentSizeFlag = (FLG>>3) & _1BIT;
         contentChecksumFlag = (FLG>>2) & _1BIT;
         dictIDFlag = FLG & _1BIT;
         /* validate */
-        if (((FLG>>1)&_1BIT) != 0) return err0r(LZ4F_ERROR_reservedFlag_set); /* Reserved bits */
+        if (((FLG>>1)&_1BIT) != 0) return err0r(LZ4F_ERROR_reservedFlag_set); /* Reserved bit */
         if (version != 1) return err0r(LZ4F_ERROR_headerVersion_wrong);        /* Version Number, only supported value */
-        if (blockChecksumFlag != 0) return err0r(LZ4F_ERROR_blockChecksum_unsupported); /* Not supported for the time being */
     }
 
     /* Frame Header Size */
@@ -1012,11 +1035,11 @@ static size_t LZ4F_decodeHeader(LZ4F_dctx* dctxPtr, const void* src, size_t srcS
 
     if (srcSize < frameHeaderSize) {
         /* not enough input to fully decode frame header */
-        if (srcPtr != dctxPtr->header)
-            memcpy(dctxPtr->header, srcPtr, srcSize);
-        dctxPtr->tmpInSize = srcSize;
-        dctxPtr->tmpInTarget = frameHeaderSize;
-        dctxPtr->dStage = dstage_storeHeader;
+        if (srcPtr != dctx->header)
+            memcpy(dctx->header, srcPtr, srcSize);
+        dctx->tmpInSize = srcSize;
+        dctx->tmpInTarget = frameHeaderSize;
+        dctx->dStage = dstage_storeFrameHeader;
         return srcSize;
     }
 
@@ -1035,49 +1058,50 @@ static size_t LZ4F_decodeHeader(LZ4F_dctx* dctxPtr, const void* src, size_t srcS
     }
 
     /* save */
-    dctxPtr->frameInfo.blockMode = (LZ4F_blockMode_t)blockMode;
-    dctxPtr->frameInfo.contentChecksumFlag = (LZ4F_contentChecksum_t)contentChecksumFlag;
-    dctxPtr->frameInfo.blockSizeID = (LZ4F_blockSizeID_t)blockSizeID;
-    dctxPtr->maxBlockSize = LZ4F_getBlockSize(blockSizeID);
+    dctx->frameInfo.blockMode = (LZ4F_blockMode_t)blockMode;
+    dctx->frameInfo.blockChecksumFlag = (LZ4F_blockChecksum_t)blockChecksumFlag;
+    dctx->frameInfo.contentChecksumFlag = (LZ4F_contentChecksum_t)contentChecksumFlag;
+    dctx->frameInfo.blockSizeID = (LZ4F_blockSizeID_t)blockSizeID;
+    dctx->maxBlockSize = LZ4F_getBlockSize(blockSizeID);
     if (contentSizeFlag)
-        dctxPtr->frameRemainingSize =
-            dctxPtr->frameInfo.contentSize = LZ4F_readLE64(srcPtr+6);
+        dctx->frameRemainingSize =
+            dctx->frameInfo.contentSize = LZ4F_readLE64(srcPtr+6);
     if (dictIDFlag)
-        dctxPtr->frameInfo.dictID = LZ4F_readLE32(srcPtr + frameHeaderSize - 5);
+        dctx->frameInfo.dictID = LZ4F_readLE32(srcPtr + frameHeaderSize - 5);
 
-    dctxPtr->dStage = dstage_init;
+    dctx->dStage = dstage_init;
 
     return frameHeaderSize;
 }
 
 
 /*! LZ4F_getFrameInfo() :
- * This function extracts frame parameters (max blockSize, frame checksum, etc.).
- * Usage is optional. Objective is to provide relevant information for allocation purposes.
- * This function works in 2 situations :
+ *  This function extracts frame parameters (max blockSize, frame checksum, etc.).
+ *  Usage is optional. Objective is to provide relevant information for allocation purposes.
+ *  This function works in 2 situations :
  *   - At the beginning of a new frame, in which case it will decode this information from `srcBuffer`, and start the decoding process.
  *     Amount of input data provided must be large enough to successfully decode the frame header.
  *     A header size is variable, but is guaranteed to be <= LZ4F_HEADER_SIZE_MAX bytes. It's possible to provide more input data than this minimum.
  *   - After decoding has been started. In which case, no input is read, frame parameters are extracted from dctx.
- * The number of bytes consumed from srcBuffer will be updated within *srcSizePtr (necessarily <= original value).
- * Decompression must resume from (srcBuffer + *srcSizePtr).
+ *  The number of bytes consumed from srcBuffer will be updated within *srcSizePtr (necessarily <= original value).
+ *  Decompression must resume from (srcBuffer + *srcSizePtr).
  * @return : an hint about how many srcSize bytes LZ4F_decompress() expects for next call,
  *           or an error code which can be tested using LZ4F_isError()
- * note 1 : in case of error, dctx is not modified. Decoding operations can resume from where they stopped.
- * note 2 : frame parameters are *copied into* an already allocated LZ4F_frameInfo_t structure.
+ *  note 1 : in case of error, dctx is not modified. Decoding operations can resume from where they stopped.
+ *  note 2 : frame parameters are *copied into* an already allocated LZ4F_frameInfo_t structure.
  */
-LZ4F_errorCode_t LZ4F_getFrameInfo(LZ4F_dctx* dctxPtr, LZ4F_frameInfo_t* frameInfoPtr,
+LZ4F_errorCode_t LZ4F_getFrameInfo(LZ4F_dctx* dctx, LZ4F_frameInfo_t* frameInfoPtr,
                                    const void* srcBuffer, size_t* srcSizePtr)
 {
-    if (dctxPtr->dStage > dstage_storeHeader) {  /* assumption :  dstage_* header enum at beginning of range */
+    if (dctx->dStage > dstage_storeFrameHeader) {  /* assumption :  dstage_* header enum at beginning of range */
         /* frameInfo already decoded */
         size_t o=0, i=0;
         *srcSizePtr = 0;
-        *frameInfoPtr = dctxPtr->frameInfo;
+        *frameInfoPtr = dctx->frameInfo;
         /* returns : recommended nb of bytes for LZ4F_decompress() */
-        return LZ4F_decompress(dctxPtr, NULL, &o, NULL, &i, NULL);
+        return LZ4F_decompress(dctx, NULL, &o, NULL, &i, NULL);
     } else {
-        if (dctxPtr->dStage == dstage_storeHeader) {
+        if (dctx->dStage == dstage_storeFrameHeader) {
             /* frame decoding already started, in the middle of header => automatic fail */
             *srcSizePtr = 0;
             return err0r(LZ4F_ERROR_frameDecoding_alreadyStarted);
@@ -1090,73 +1114,75 @@ LZ4F_errorCode_t LZ4F_getFrameInfo(LZ4F_dctx* dctxPtr, LZ4F_frameInfo_t* frameIn
                 return err0r(LZ4F_ERROR_frameHeader_incomplete);
             }
 
-            decodeResult = LZ4F_decodeHeader(dctxPtr, srcBuffer, hSize);
+            decodeResult = LZ4F_decodeHeader(dctx, srcBuffer, hSize);
             if (LZ4F_isError(decodeResult)) {
                 *srcSizePtr = 0;
             } else {
                 *srcSizePtr = decodeResult;
                 decodeResult = BHSize;   /* block header size */
             }
-            *frameInfoPtr = dctxPtr->frameInfo;
+            *frameInfoPtr = dctx->frameInfo;
             return decodeResult;
     }   }
 }
 
 
-static void LZ4F_updateDict(LZ4F_dctx* dctxPtr, const BYTE* dstPtr, size_t dstSize, const BYTE* dstPtr0, unsigned withinTmp)
+/* LZ4F_updateDict() :
+ * only used for LZ4F_blockLinked mode */
+static void LZ4F_updateDict(LZ4F_dctx* dctx, const BYTE* dstPtr, size_t dstSize, const BYTE* dstPtr0, unsigned withinTmp)
 {
-    if (dctxPtr->dictSize==0)
-        dctxPtr->dict = (const BYTE*)dstPtr;   /* priority to dictionary continuity */
+    if (dctx->dictSize==0)
+        dctx->dict = (const BYTE*)dstPtr;   /* priority to dictionary continuity */
 
-    if (dctxPtr->dict + dctxPtr->dictSize == dstPtr) {  /* dictionary continuity */
-        dctxPtr->dictSize += dstSize;
+    if (dctx->dict + dctx->dictSize == dstPtr) {  /* dictionary continuity */
+        dctx->dictSize += dstSize;
         return;
     }
 
     if (dstPtr - dstPtr0 + dstSize >= 64 KB) {  /* dstBuffer large enough to become dictionary */
-        dctxPtr->dict = (const BYTE*)dstPtr0;
-        dctxPtr->dictSize = dstPtr - dstPtr0 + dstSize;
+        dctx->dict = (const BYTE*)dstPtr0;
+        dctx->dictSize = dstPtr - dstPtr0 + dstSize;
         return;
     }
 
-    if ((withinTmp) && (dctxPtr->dict == dctxPtr->tmpOutBuffer)) {
-        /* assumption : dctxPtr->dict + dctxPtr->dictSize == dctxPtr->tmpOut + dctxPtr->tmpOutStart */
-        dctxPtr->dictSize += dstSize;
+    if ((withinTmp) && (dctx->dict == dctx->tmpOutBuffer)) {
+        /* assumption : dctx->dict + dctx->dictSize == dctx->tmpOut + dctx->tmpOutStart */
+        dctx->dictSize += dstSize;
         return;
     }
 
     if (withinTmp) { /* copy relevant dict portion in front of tmpOut within tmpOutBuffer */
-        size_t const preserveSize = dctxPtr->tmpOut - dctxPtr->tmpOutBuffer;
-        size_t copySize = 64 KB - dctxPtr->tmpOutSize;
-        const BYTE* const oldDictEnd = dctxPtr->dict + dctxPtr->dictSize - dctxPtr->tmpOutStart;
-        if (dctxPtr->tmpOutSize > 64 KB) copySize = 0;
+        size_t const preserveSize = dctx->tmpOut - dctx->tmpOutBuffer;
+        size_t copySize = 64 KB - dctx->tmpOutSize;
+        const BYTE* const oldDictEnd = dctx->dict + dctx->dictSize - dctx->tmpOutStart;
+        if (dctx->tmpOutSize > 64 KB) copySize = 0;
         if (copySize > preserveSize) copySize = preserveSize;
 
-        memcpy(dctxPtr->tmpOutBuffer + preserveSize - copySize, oldDictEnd - copySize, copySize);
+        memcpy(dctx->tmpOutBuffer + preserveSize - copySize, oldDictEnd - copySize, copySize);
 
-        dctxPtr->dict = dctxPtr->tmpOutBuffer;
-        dctxPtr->dictSize = preserveSize + dctxPtr->tmpOutStart + dstSize;
+        dctx->dict = dctx->tmpOutBuffer;
+        dctx->dictSize = preserveSize + dctx->tmpOutStart + dstSize;
         return;
     }
 
-    if (dctxPtr->dict == dctxPtr->tmpOutBuffer) {    /* copy dst into tmp to complete dict */
-        if (dctxPtr->dictSize + dstSize > dctxPtr->maxBufferSize) {  /* tmp buffer not large enough */
+    if (dctx->dict == dctx->tmpOutBuffer) {    /* copy dst into tmp to complete dict */
+        if (dctx->dictSize + dstSize > dctx->maxBufferSize) {  /* tmp buffer not large enough */
             size_t const preserveSize = 64 KB - dstSize;   /* note : dstSize < 64 KB */
-            memcpy(dctxPtr->tmpOutBuffer, dctxPtr->dict + dctxPtr->dictSize - preserveSize, preserveSize);
-            dctxPtr->dictSize = preserveSize;
+            memcpy(dctx->tmpOutBuffer, dctx->dict + dctx->dictSize - preserveSize, preserveSize);
+            dctx->dictSize = preserveSize;
         }
-        memcpy(dctxPtr->tmpOutBuffer + dctxPtr->dictSize, dstPtr, dstSize);
-        dctxPtr->dictSize += dstSize;
+        memcpy(dctx->tmpOutBuffer + dctx->dictSize, dstPtr, dstSize);
+        dctx->dictSize += dstSize;
         return;
     }
 
     /* join dict & dest into tmp */
     {   size_t preserveSize = 64 KB - dstSize;   /* note : dstSize < 64 KB */
-        if (preserveSize > dctxPtr->dictSize) preserveSize = dctxPtr->dictSize;
-        memcpy(dctxPtr->tmpOutBuffer, dctxPtr->dict + dctxPtr->dictSize - preserveSize, preserveSize);
-        memcpy(dctxPtr->tmpOutBuffer + preserveSize, dstPtr, dstSize);
-        dctxPtr->dict = dctxPtr->tmpOutBuffer;
-        dctxPtr->dictSize = preserveSize + dstSize;
+        if (preserveSize > dctx->dictSize) preserveSize = dctx->dictSize;
+        memcpy(dctx->tmpOutBuffer, dctx->dict + dctx->dictSize - preserveSize, preserveSize);
+        memcpy(dctx->tmpOutBuffer + preserveSize, dstPtr, dstSize);
+        dctx->dict = dctx->tmpOutBuffer;
+        dctx->dictSize = preserveSize + dstSize;
     }
 }
 
@@ -1180,7 +1206,7 @@ static void LZ4F_updateDict(LZ4F_dctx* dctxPtr, const BYTE* dstPtr, size_t dstSi
  *  When a frame is fully decoded, @return will be 0.
  *  If decompression failed, @return is an error code which can be tested using LZ4F_isError().
  */
-size_t LZ4F_decompress(LZ4F_dctx* dctxPtr,
+size_t LZ4F_decompress(LZ4F_dctx* dctx,
                        void* dstBuffer, size_t* dstSizePtr,
                        const void* srcBuffer, size_t* srcSizePtr,
                        const LZ4F_decompressOptions_t* decompressOptionsPtr)
@@ -1202,243 +1228,288 @@ size_t LZ4F_decompress(LZ4F_dctx* dctxPtr,
     *srcSizePtr = 0;
     *dstSizePtr = 0;
 
-    /* behaves like a state machine */
+    /* behaves as a state machine */
 
     while (doAnotherStage) {
 
-        switch(dctxPtr->dStage)
+        switch(dctx->dStage)
         {
 
-        case dstage_getHeader:
+        case dstage_getFrameHeader:
             if ((size_t)(srcEnd-srcPtr) >= maxFHSize) {  /* enough to decode - shortcut */
-                LZ4F_errorCode_t const hSize = LZ4F_decodeHeader(dctxPtr, srcPtr, srcEnd-srcPtr);  /* will change dStage appropriately */
+                size_t const hSize = LZ4F_decodeHeader(dctx, srcPtr, srcEnd-srcPtr);  /* will update dStage appropriately */
                 if (LZ4F_isError(hSize)) return hSize;
                 srcPtr += hSize;
                 break;
             }
-            dctxPtr->tmpInSize = 0;
+            dctx->tmpInSize = 0;
             if (srcEnd-srcPtr == 0) return minFHSize;   /* 0-size input */
-            dctxPtr->tmpInTarget = minFHSize;   /* minimum to attempt decode */
-            dctxPtr->dStage = dstage_storeHeader;
+            dctx->tmpInTarget = minFHSize;   /* minimum to attempt decode */
+            dctx->dStage = dstage_storeFrameHeader;
             /* fall-through */
 
-        case dstage_storeHeader:
-            {   size_t sizeToCopy = dctxPtr->tmpInTarget - dctxPtr->tmpInSize;
-                if (sizeToCopy > (size_t)(srcEnd - srcPtr)) sizeToCopy =  srcEnd - srcPtr;
-                memcpy(dctxPtr->header + dctxPtr->tmpInSize, srcPtr, sizeToCopy);
-                dctxPtr->tmpInSize += sizeToCopy;
+        case dstage_storeFrameHeader:
+            {   size_t const sizeToCopy = MIN(dctx->tmpInTarget - dctx->tmpInSize, (size_t)(srcEnd - srcPtr));
+                memcpy(dctx->header + dctx->tmpInSize, srcPtr, sizeToCopy);
+                dctx->tmpInSize += sizeToCopy;
                 srcPtr += sizeToCopy;
-                if (dctxPtr->tmpInSize < dctxPtr->tmpInTarget) {
-                    nextSrcSizeHint = (dctxPtr->tmpInTarget - dctxPtr->tmpInSize) + BHSize;   /* rest of header + nextBlockHeader */
+                if (dctx->tmpInSize < dctx->tmpInTarget) {
+                    nextSrcSizeHint = (dctx->tmpInTarget - dctx->tmpInSize) + BHSize;   /* rest of header + nextBlockHeader */
                     doAnotherStage = 0;   /* not enough src data, ask for some more */
                     break;
                 }
-                {   LZ4F_errorCode_t const hSize = LZ4F_decodeHeader(dctxPtr, dctxPtr->header, dctxPtr->tmpInTarget);  /* will change dStage appropriately */
+                {   size_t const hSize = LZ4F_decodeHeader(dctx, dctx->header, dctx->tmpInTarget);  /* will update dStage appropriately */
                     if (LZ4F_isError(hSize)) return hSize;
                 }
                 break;
             }
 
         case dstage_init:
-            if (dctxPtr->frameInfo.contentChecksumFlag) XXH32_reset(&(dctxPtr->xxh), 0);
+            if (dctx->frameInfo.contentChecksumFlag) XXH32_reset(&(dctx->xxh), 0);
             /* internal buffers allocation */
-            {   size_t const bufferNeeded = dctxPtr->maxBlockSize + ((dctxPtr->frameInfo.blockMode==LZ4F_blockLinked) * 128 KB);
-                if (bufferNeeded > dctxPtr->maxBufferSize) {   /* tmp buffers too small */
-                    dctxPtr->maxBufferSize = 0;   /* ensure allocation will be re-attempted on next entry*/
-                    FREEMEM(dctxPtr->tmpIn);
-                    dctxPtr->tmpIn = (BYTE*)ALLOCATOR(dctxPtr->maxBlockSize);
-                    if (dctxPtr->tmpIn == NULL) return err0r(LZ4F_ERROR_allocation_failed);
-                    FREEMEM(dctxPtr->tmpOutBuffer);
-                    dctxPtr->tmpOutBuffer= (BYTE*)ALLOCATOR(bufferNeeded);
-                    if (dctxPtr->tmpOutBuffer== NULL) return err0r(LZ4F_ERROR_allocation_failed);
-                    dctxPtr->maxBufferSize = bufferNeeded;
+            {   size_t const bufferNeeded = dctx->maxBlockSize + ((dctx->frameInfo.blockMode==LZ4F_blockLinked) * 128 KB) + 4 /* block checksum */;
+                if (bufferNeeded > dctx->maxBufferSize) {   /* tmp buffers too small */
+                    dctx->maxBufferSize = 0;   /* ensure allocation will be re-attempted on next entry*/
+                    FREEMEM(dctx->tmpIn);
+                    dctx->tmpIn = (BYTE*)ALLOCATOR(dctx->maxBlockSize);
+                    if (dctx->tmpIn == NULL) return err0r(LZ4F_ERROR_allocation_failed);
+                    FREEMEM(dctx->tmpOutBuffer);
+                    dctx->tmpOutBuffer= (BYTE*)ALLOCATOR(bufferNeeded);
+                    if (dctx->tmpOutBuffer== NULL) return err0r(LZ4F_ERROR_allocation_failed);
+                    dctx->maxBufferSize = bufferNeeded;
             }   }
-            dctxPtr->tmpInSize = 0;
-            dctxPtr->tmpInTarget = 0;
-            dctxPtr->tmpOut = dctxPtr->tmpOutBuffer;
-            dctxPtr->tmpOutStart = 0;
-            dctxPtr->tmpOutSize = 0;
+            dctx->tmpInSize = 0;
+            dctx->tmpInTarget = 0;
+            dctx->tmpOut = dctx->tmpOutBuffer;
+            dctx->tmpOutStart = 0;
+            dctx->tmpOutSize = 0;
 
-            dctxPtr->dStage = dstage_getCBlockSize;
+            dctx->dStage = dstage_getBlockHeader;
             /* fall-through */
 
-        case dstage_getCBlockSize:
+        case dstage_getBlockHeader:
             if ((size_t)(srcEnd - srcPtr) >= BHSize) {
                 selectedIn = srcPtr;
                 srcPtr += BHSize;
             } else {
                 /* not enough input to read cBlockSize field */
-                dctxPtr->tmpInSize = 0;
-                dctxPtr->dStage = dstage_storeCBlockSize;
+                dctx->tmpInSize = 0;
+                dctx->dStage = dstage_storeBlockHeader;
             }
 
-            if (dctxPtr->dStage == dstage_storeCBlockSize)   /* can be skipped */
-        case dstage_storeCBlockSize:
-            {   size_t sizeToCopy = BHSize - dctxPtr->tmpInSize;
+            if (dctx->dStage == dstage_storeBlockHeader)   /* can be skipped */
+        case dstage_storeBlockHeader:
+            {   size_t sizeToCopy = BHSize - dctx->tmpInSize;
                 if (sizeToCopy > (size_t)(srcEnd - srcPtr)) sizeToCopy = srcEnd - srcPtr;
-                memcpy(dctxPtr->tmpIn + dctxPtr->tmpInSize, srcPtr, sizeToCopy);
+                memcpy(dctx->tmpIn + dctx->tmpInSize, srcPtr, sizeToCopy);
                 srcPtr += sizeToCopy;
-                dctxPtr->tmpInSize += sizeToCopy;
-                if (dctxPtr->tmpInSize < BHSize) {   /* not enough input for cBlockSize */
-                    nextSrcSizeHint = BHSize - dctxPtr->tmpInSize;
+                dctx->tmpInSize += sizeToCopy;
+                if (dctx->tmpInSize < BHSize) {   /* not enough input for cBlockSize */
+                    nextSrcSizeHint = BHSize - dctx->tmpInSize;
                     doAnotherStage  = 0;
                     break;
                 }
-                selectedIn = dctxPtr->tmpIn;
+                selectedIn = dctx->tmpIn;
             }
 
-        /* case dstage_decodeCBlockSize: */   /* no more direct access, to remove scan-build warning */
+        /* decode block header */
             {   size_t const nextCBlockSize = LZ4F_readLE32(selectedIn) & 0x7FFFFFFFU;
-                if (nextCBlockSize==0) {  /* frameEnd signal, no more CBlock */
-                    dctxPtr->dStage = dstage_getSuffix;
+                size_t const crcSize = dctx->frameInfo.blockChecksumFlag * 4;
+                if (nextCBlockSize==0) {  /* frameEnd signal, no more block */
+                    dctx->dStage = dstage_getSuffix;
                     break;
                 }
-                if (nextCBlockSize > dctxPtr->maxBlockSize)
+                if (nextCBlockSize > dctx->maxBlockSize)
                     return err0r(LZ4F_ERROR_maxBlockSize_invalid);
-                dctxPtr->tmpInTarget = nextCBlockSize;
                 if (LZ4F_readLE32(selectedIn) & LZ4F_BLOCKUNCOMPRESSED_FLAG) {
-                    dctxPtr->dStage = dstage_copyDirect;
+                    /* next block is uncompressed */
+                    dctx->tmpInTarget = nextCBlockSize;
+                    if (dctx->frameInfo.blockChecksumFlag) {
+                        XXH32_reset(&dctx->blockChecksum, 0);
+                    }
+                    dctx->dStage = dstage_copyDirect;
                     break;
                 }
-                dctxPtr->dStage = dstage_getCBlock;
+                /* next block is a compressed block */
+                dctx->tmpInTarget = nextCBlockSize + crcSize;
+                dctx->dStage = dstage_getCBlock;
                 if (dstPtr==dstEnd) {
-                    nextSrcSizeHint = nextCBlockSize + BHSize;
+                    nextSrcSizeHint = nextCBlockSize + crcSize + BHSize;
                     doAnotherStage = 0;
                 }
                 break;
             }
 
         case dstage_copyDirect:   /* uncompressed block */
-            {   size_t sizeToCopy = dctxPtr->tmpInTarget;
-                if ((size_t)(srcEnd-srcPtr) < sizeToCopy) sizeToCopy = srcEnd - srcPtr;
-                if ((size_t)(dstEnd-dstPtr) < sizeToCopy) sizeToCopy = dstEnd - dstPtr;
+            {   size_t const minBuffSize = MIN((size_t)(srcEnd-srcPtr), (size_t)(dstEnd-dstPtr));
+                size_t const sizeToCopy = MIN(dctx->tmpInTarget, minBuffSize);
                 memcpy(dstPtr, srcPtr, sizeToCopy);
-                if (dctxPtr->frameInfo.contentChecksumFlag)
-                    XXH32_update(&(dctxPtr->xxh), srcPtr, sizeToCopy);
-                if (dctxPtr->frameInfo.contentSize)
-                    dctxPtr->frameRemainingSize -= sizeToCopy;
+                if (dctx->frameInfo.blockChecksumFlag) {
+                    XXH32_update(&dctx->blockChecksum, srcPtr, sizeToCopy);
+                }
+                if (dctx->frameInfo.contentChecksumFlag)
+                    XXH32_update(&dctx->xxh, srcPtr, sizeToCopy);
+                if (dctx->frameInfo.contentSize)
+                    dctx->frameRemainingSize -= sizeToCopy;
 
-                /* dictionary management */
-                if (dctxPtr->frameInfo.blockMode==LZ4F_blockLinked)
-                    LZ4F_updateDict(dctxPtr, dstPtr, sizeToCopy, dstStart, 0);
+                /* history management (linked blocks only)*/
+                if (dctx->frameInfo.blockMode == LZ4F_blockLinked)
+                    LZ4F_updateDict(dctx, dstPtr, sizeToCopy, dstStart, 0);
 
                 srcPtr += sizeToCopy;
                 dstPtr += sizeToCopy;
-                if (sizeToCopy == dctxPtr->tmpInTarget) {  /* all copied */
-                    dctxPtr->dStage = dstage_getCBlockSize;
+                if (sizeToCopy == dctx->tmpInTarget) {   /* all done */
+                    if (dctx->frameInfo.blockChecksumFlag) {
+                        dctx->tmpInSize = 0;
+                        dctx->dStage = dstage_getBlockChecksum;
+                    } else
+                        dctx->dStage = dstage_getBlockHeader;  /* new block */
                     break;
                 }
-                dctxPtr->tmpInTarget -= sizeToCopy;   /* still need to copy more */
-                nextSrcSizeHint = dctxPtr->tmpInTarget + BHSize;
+                dctx->tmpInTarget -= sizeToCopy;  /* need to copy more */
+                nextSrcSizeHint = dctx->tmpInTarget +
+                                + dctx->frameInfo.contentChecksumFlag * 4  /* block checksum */
+                                + BHSize /* next header size */;
                 doAnotherStage = 0;
                 break;
             }
 
+        /* check block checksum for recently transferred uncompressed block */
+        case dstage_getBlockChecksum:
+            {   const void* crcSrc;
+                if ((srcEnd-srcPtr >= 4) && (dctx->tmpInSize==0)) {
+                    crcSrc = srcPtr;
+                    srcPtr += 4;
+                } else {
+                    size_t const stillToCopy = 4 - dctx->tmpInSize;
+                    size_t const sizeToCopy = MIN(stillToCopy, (size_t)(srcEnd-srcPtr));
+                    memcpy(dctx->header + dctx->tmpInSize, srcPtr, sizeToCopy);
+                    dctx->tmpInSize += sizeToCopy;
+                    srcPtr += sizeToCopy;
+                    if (dctx->tmpInSize < 4) {  /* all input consumed */
+                        doAnotherStage = 0;
+                        break;
+                    }
+                    crcSrc = dctx->header;
+                }
+                {   U32 const readCRC = LZ4F_readLE32(crcSrc);
+                    U32 const calcCRC = XXH32_digest(&dctx->blockChecksum);
+                    if (readCRC != calcCRC)
+                        return err0r(LZ4F_ERROR_blockChecksum_invalid);
+                }
+            }
+            dctx->dStage = dstage_getBlockHeader;  /* new block */
+            break;
+
         case dstage_getCBlock:   /* entry from dstage_decodeCBlockSize */
-            if ((size_t)(srcEnd-srcPtr) < dctxPtr->tmpInTarget) {
-                dctxPtr->tmpInSize = 0;
-                dctxPtr->dStage = dstage_storeCBlock;
+            if ((size_t)(srcEnd-srcPtr) < dctx->tmpInTarget) {
+                dctx->tmpInSize = 0;
+                dctx->dStage = dstage_storeCBlock;
                 break;
             }
+            /* input large enough to read full block directly */
             selectedIn = srcPtr;
-            srcPtr += dctxPtr->tmpInTarget;
-            dctxPtr->dStage = dstage_decodeCBlock;
+            srcPtr += dctx->tmpInTarget;
+            dctx->dStage = dstage_decodeCBlock;
             break;
 
         case dstage_storeCBlock:
-            {   size_t sizeToCopy = dctxPtr->tmpInTarget - dctxPtr->tmpInSize;
-                if (sizeToCopy > (size_t)(srcEnd-srcPtr)) sizeToCopy = srcEnd-srcPtr;
-                memcpy(dctxPtr->tmpIn + dctxPtr->tmpInSize, srcPtr, sizeToCopy);
-                dctxPtr->tmpInSize += sizeToCopy;
+            {   size_t const sizeToCopy = MIN(dctx->tmpInTarget - dctx->tmpInSize, (size_t)(srcEnd-srcPtr));
+                memcpy(dctx->tmpIn + dctx->tmpInSize, srcPtr, sizeToCopy);
+                dctx->tmpInSize += sizeToCopy;
                 srcPtr += sizeToCopy;
-                if (dctxPtr->tmpInSize < dctxPtr->tmpInTarget) { /* need more input */
-                    nextSrcSizeHint = (dctxPtr->tmpInTarget - dctxPtr->tmpInSize) + BHSize;
+                if (dctx->tmpInSize < dctx->tmpInTarget) { /* need more input */
+                    nextSrcSizeHint = (dctx->tmpInTarget - dctx->tmpInSize) + BHSize;
                     doAnotherStage=0;
                     break;
                 }
-                selectedIn = dctxPtr->tmpIn;
-                dctxPtr->dStage = dstage_decodeCBlock;
+                selectedIn = dctx->tmpIn;
+                dctx->dStage = dstage_decodeCBlock;
             }
             /* fall-through */
 
+        /* At this stage, input is large enough to decode a block */
         case dstage_decodeCBlock:
-            if ((size_t)(dstEnd-dstPtr) < dctxPtr->maxBlockSize)   /* not enough place into dst : decode into tmpOut */
-                dctxPtr->dStage = dstage_decodeCBlock_intoTmp;
+            if (dctx->frameInfo.blockChecksumFlag) {
+                dctx->tmpInTarget -= 4;
+                {   U32 const readBlockCrc = LZ4F_readLE32(selectedIn + dctx->tmpInTarget);
+                    U32 const calcBlockCrc = XXH32(selectedIn, dctx->tmpInTarget, 0);
+                    if (readBlockCrc != calcBlockCrc)
+                        return err0r(LZ4F_ERROR_blockChecksum_invalid);
+            }   }
+            if ((size_t)(dstEnd-dstPtr) < dctx->maxBlockSize)   /* not enough place into dst : decode into tmpOut */
+                dctx->dStage = dstage_decodeCBlock_intoTmp;
             else
-                dctxPtr->dStage = dstage_decodeCBlock_intoDst;
+                dctx->dStage = dstage_decodeCBlock_intoDst;
             break;
 
         case dstage_decodeCBlock_intoDst:
             {   int const decodedSize = LZ4_decompress_safe_usingDict(
                         (const char*)selectedIn, (char*)dstPtr,
-                        (int)dctxPtr->tmpInTarget, (int)dctxPtr->maxBlockSize,
-                        (const char*)dctxPtr->dict, (int)dctxPtr->dictSize);
+                        (int)dctx->tmpInTarget, (int)dctx->maxBlockSize,
+                        (const char*)dctx->dict, (int)dctx->dictSize);
                 if (decodedSize < 0) return err0r(LZ4F_ERROR_GENERIC);   /* decompression failed */
-                if (dctxPtr->frameInfo.contentChecksumFlag)
-                    XXH32_update(&(dctxPtr->xxh), dstPtr, decodedSize);
-                if (dctxPtr->frameInfo.contentSize)
-                    dctxPtr->frameRemainingSize -= decodedSize;
+                if (dctx->frameInfo.contentChecksumFlag)
+                    XXH32_update(&(dctx->xxh), dstPtr, decodedSize);
+                if (dctx->frameInfo.contentSize)
+                    dctx->frameRemainingSize -= decodedSize;
 
                 /* dictionary management */
-                if (dctxPtr->frameInfo.blockMode==LZ4F_blockLinked)
-                    LZ4F_updateDict(dctxPtr, dstPtr, decodedSize, dstStart, 0);
+                if (dctx->frameInfo.blockMode==LZ4F_blockLinked)
+                    LZ4F_updateDict(dctx, dstPtr, decodedSize, dstStart, 0);
 
                 dstPtr += decodedSize;
-                dctxPtr->dStage = dstage_getCBlockSize;
+                dctx->dStage = dstage_getBlockHeader;
                 break;
             }
 
         case dstage_decodeCBlock_intoTmp:
             /* not enough place into dst : decode into tmpOut */
-            {   int decodedSize;
-
-                /* ensure enough place for tmpOut */
-                if (dctxPtr->frameInfo.blockMode == LZ4F_blockLinked) {
-                    if (dctxPtr->dict == dctxPtr->tmpOutBuffer) {
-                        if (dctxPtr->dictSize > 128 KB) {
-                            memcpy(dctxPtr->tmpOutBuffer, dctxPtr->dict + dctxPtr->dictSize - 64 KB, 64 KB);
-                            dctxPtr->dictSize = 64 KB;
-                        }
-                        dctxPtr->tmpOut = dctxPtr->tmpOutBuffer + dctxPtr->dictSize;
-                    } else {  /* dict not within tmp */
-                        size_t reservedDictSpace = dctxPtr->dictSize;
-                        if (reservedDictSpace > 64 KB) reservedDictSpace = 64 KB;
-                        dctxPtr->tmpOut = dctxPtr->tmpOutBuffer + reservedDictSpace;
+
+            /* ensure enough place for tmpOut */
+            if (dctx->frameInfo.blockMode == LZ4F_blockLinked) {
+                if (dctx->dict == dctx->tmpOutBuffer) {
+                    if (dctx->dictSize > 128 KB) {
+                        memcpy(dctx->tmpOutBuffer, dctx->dict + dctx->dictSize - 64 KB, 64 KB);
+                        dctx->dictSize = 64 KB;
                     }
+                    dctx->tmpOut = dctx->tmpOutBuffer + dctx->dictSize;
+                } else {  /* dict not within tmp */
+                    size_t const reservedDictSpace = MIN(dctx->dictSize, 64 KB);
+                    dctx->tmpOut = dctx->tmpOutBuffer + reservedDictSpace;
                 }
+            }
 
-                /* Decode */
-                decodedSize = LZ4_decompress_safe_usingDict(
-                        (const char*)selectedIn, (char*)dctxPtr->tmpOut,
-                        (int)dctxPtr->tmpInTarget, (int)dctxPtr->maxBlockSize,
-                        (const char*)dctxPtr->dict, (int)dctxPtr->dictSize);
-                if (decodedSize < 0)
-                    return err0r(LZ4F_ERROR_decompressionFailed);   /* decompression failed */
-                if (dctxPtr->frameInfo.contentChecksumFlag)
-                    XXH32_update(&(dctxPtr->xxh), dctxPtr->tmpOut, decodedSize);
-                if (dctxPtr->frameInfo.contentSize)
-                    dctxPtr->frameRemainingSize -= decodedSize;
-                dctxPtr->tmpOutSize = decodedSize;
-                dctxPtr->tmpOutStart = 0;
-                dctxPtr->dStage = dstage_flushOut;
-                break;
+            /* Decode block */
+            {   int const decodedSize = LZ4_decompress_safe_usingDict(
+                        (const char*)selectedIn, (char*)dctx->tmpOut,
+                        (int)dctx->tmpInTarget, (int)dctx->maxBlockSize,
+                        (const char*)dctx->dict, (int)dctx->dictSize);
+                if (decodedSize < 0)  /* decompression failed */
+                    return err0r(LZ4F_ERROR_decompressionFailed);
+                if (dctx->frameInfo.contentChecksumFlag)
+                    XXH32_update(&(dctx->xxh), dctx->tmpOut, decodedSize);
+                if (dctx->frameInfo.contentSize)
+                    dctx->frameRemainingSize -= decodedSize;
+                dctx->tmpOutSize = decodedSize;
+                dctx->tmpOutStart = 0;
+                dctx->dStage = dstage_flushOut;
             }
+            /* fall-through */
 
         case dstage_flushOut:  /* flush decoded data from tmpOut to dstBuffer */
-            {   size_t sizeToCopy = dctxPtr->tmpOutSize - dctxPtr->tmpOutStart;
-                if (sizeToCopy > (size_t)(dstEnd-dstPtr)) sizeToCopy = dstEnd-dstPtr;
-                memcpy(dstPtr, dctxPtr->tmpOut + dctxPtr->tmpOutStart, sizeToCopy);
+            {   size_t const sizeToCopy = MIN(dctx->tmpOutSize - dctx->tmpOutStart, (size_t)(dstEnd-dstPtr));
+                memcpy(dstPtr, dctx->tmpOut + dctx->tmpOutStart, sizeToCopy);
 
                 /* dictionary management */
-                if (dctxPtr->frameInfo.blockMode==LZ4F_blockLinked)
-                    LZ4F_updateDict(dctxPtr, dstPtr, sizeToCopy, dstStart, 1);
+                if (dctx->frameInfo.blockMode==LZ4F_blockLinked)
+                    LZ4F_updateDict(dctx, dstPtr, sizeToCopy, dstStart, 1);
 
-                dctxPtr->tmpOutStart += sizeToCopy;
+                dctx->tmpOutStart += sizeToCopy;
                 dstPtr += sizeToCopy;
 
-                /* end of flush ? */
-                if (dctxPtr->tmpOutStart == dctxPtr->tmpOutSize) {
-                    dctxPtr->dStage = dstage_getCBlockSize;
+                if (dctx->tmpOutStart == dctx->tmpOutSize) { /* all flushed */
+                    dctx->dStage = dstage_getBlockHeader;  /* get next block */
                     break;
                 }
                 nextSrcSizeHint = BHSize;
@@ -1447,46 +1518,47 @@ size_t LZ4F_decompress(LZ4F_dctx* dctxPtr,
             }
 
         case dstage_getSuffix:
-            {   size_t const suffixSize = dctxPtr->frameInfo.contentChecksumFlag * 4;
-                if (dctxPtr->frameRemainingSize)
+            {   size_t const suffixSize = dctx->frameInfo.contentChecksumFlag * 4;
+                if (dctx->frameRemainingSize)
                     return err0r(LZ4F_ERROR_frameSize_wrong);   /* incorrect frame size decoded */
                 if (suffixSize == 0) {  /* frame completed */
                     nextSrcSizeHint = 0;
-                    LZ4F_resetDecompressionContext(dctxPtr);
+                    LZ4F_resetDecompressionContext(dctx);
                     doAnotherStage = 0;
                     break;
                 }
                 if ((srcEnd - srcPtr) < 4) {  /* not enough size for entire CRC */
-                    dctxPtr->tmpInSize = 0;
-                    dctxPtr->dStage = dstage_storeSuffix;
+                    dctx->tmpInSize = 0;
+                    dctx->dStage = dstage_storeSuffix;
                 } else {
                     selectedIn = srcPtr;
                     srcPtr += 4;
                 }
             }
 
-            if (dctxPtr->dStage == dstage_storeSuffix)   /* can be skipped */
+            if (dctx->dStage == dstage_storeSuffix)   /* can be skipped */
         case dstage_storeSuffix:
             {
-                size_t sizeToCopy = 4 - dctxPtr->tmpInSize;
+                size_t sizeToCopy = 4 - dctx->tmpInSize;
                 if (sizeToCopy > (size_t)(srcEnd - srcPtr)) sizeToCopy = srcEnd - srcPtr;
-                memcpy(dctxPtr->tmpIn + dctxPtr->tmpInSize, srcPtr, sizeToCopy);
+                memcpy(dctx->tmpIn + dctx->tmpInSize, srcPtr, sizeToCopy);
                 srcPtr += sizeToCopy;
-                dctxPtr->tmpInSize += sizeToCopy;
-                if (dctxPtr->tmpInSize < 4) { /* not enough input to read complete suffix */
-                    nextSrcSizeHint = 4 - dctxPtr->tmpInSize;
+                dctx->tmpInSize += sizeToCopy;
+                if (dctx->tmpInSize < 4) { /* not enough input to read complete suffix */
+                    nextSrcSizeHint = 4 - dctx->tmpInSize;
                     doAnotherStage=0;
                     break;
                 }
-                selectedIn = dctxPtr->tmpIn;
+                selectedIn = dctx->tmpIn;
             }
 
-        /* case dstage_checkSuffix: */   /* no direct call, to avoid scan-build warning */
+        /* case dstage_checkSuffix: */   /* no direct call, avoid scan-build warning */
             {   U32 const readCRC = LZ4F_readLE32(selectedIn);
-                U32 const resultCRC = XXH32_digest(&(dctxPtr->xxh));
-                if (readCRC != resultCRC) return err0r(LZ4F_ERROR_contentChecksum_invalid);
+                U32 const resultCRC = XXH32_digest(&(dctx->xxh));
+                if (readCRC != resultCRC)
+                    return err0r(LZ4F_ERROR_contentChecksum_invalid);
                 nextSrcSizeHint = 0;
-                LZ4F_resetDecompressionContext(dctxPtr);
+                LZ4F_resetDecompressionContext(dctx);
                 doAnotherStage = 0;
                 break;
             }
@@ -1497,80 +1569,77 @@ size_t LZ4F_decompress(LZ4F_dctx* dctxPtr,
                 srcPtr += 4;
             } else {
                 /* not enough input to read cBlockSize field */
-                dctxPtr->tmpInSize = 4;
-                dctxPtr->tmpInTarget = 8;
-                dctxPtr->dStage = dstage_storeSFrameSize;
+                dctx->tmpInSize = 4;
+                dctx->tmpInTarget = 8;
+                dctx->dStage = dstage_storeSFrameSize;
             }
 
-            if (dctxPtr->dStage == dstage_storeSFrameSize)
+            if (dctx->dStage == dstage_storeSFrameSize)
         case dstage_storeSFrameSize:
             {
-                size_t sizeToCopy = dctxPtr->tmpInTarget - dctxPtr->tmpInSize;
-                if (sizeToCopy > (size_t)(srcEnd - srcPtr))
-                    sizeToCopy = srcEnd - srcPtr;
-                memcpy(dctxPtr->header + dctxPtr->tmpInSize, srcPtr, sizeToCopy);
+                size_t const sizeToCopy = MIN(dctx->tmpInTarget - dctx->tmpInSize,
+                                             (size_t)(srcEnd - srcPtr) );
+                memcpy(dctx->header + dctx->tmpInSize, srcPtr, sizeToCopy);
                 srcPtr += sizeToCopy;
-                dctxPtr->tmpInSize += sizeToCopy;
-                if (dctxPtr->tmpInSize < dctxPtr->tmpInTarget) {
+                dctx->tmpInSize += sizeToCopy;
+                if (dctx->tmpInSize < dctx->tmpInTarget) {
                     /* not enough input to get full sBlockSize; wait for more */
-                    nextSrcSizeHint = dctxPtr->tmpInTarget - dctxPtr->tmpInSize;
+                    nextSrcSizeHint = dctx->tmpInTarget - dctx->tmpInSize;
                     doAnotherStage = 0;
                     break;
                 }
-                selectedIn = dctxPtr->header + 4;
+                selectedIn = dctx->header + 4;
             }
 
         /* case dstage_decodeSFrameSize: */   /* no direct access */
             {   size_t const SFrameSize = LZ4F_readLE32(selectedIn);
-                dctxPtr->frameInfo.contentSize = SFrameSize;
-                dctxPtr->tmpInTarget = SFrameSize;
-                dctxPtr->dStage = dstage_skipSkippable;
+                dctx->frameInfo.contentSize = SFrameSize;
+                dctx->tmpInTarget = SFrameSize;
+                dctx->dStage = dstage_skipSkippable;
                 break;
             }
 
         case dstage_skipSkippable:
-            {   size_t skipSize = dctxPtr->tmpInTarget;
-                if (skipSize > (size_t)(srcEnd-srcPtr))
-                    skipSize = srcEnd-srcPtr;
+            {   size_t const skipSize = MIN(dctx->tmpInTarget, (size_t)(srcEnd-srcPtr));
                 srcPtr += skipSize;
-                dctxPtr->tmpInTarget -= skipSize;
+                dctx->tmpInTarget -= skipSize;
                 doAnotherStage = 0;
-                nextSrcSizeHint = dctxPtr->tmpInTarget;
-                if (nextSrcSizeHint) break;
-                LZ4F_resetDecompressionContext(dctxPtr);
+                nextSrcSizeHint = dctx->tmpInTarget;
+                if (nextSrcSizeHint) break;  /* still more to skip */
+                LZ4F_resetDecompressionContext(dctx);
                 break;
             }
         }
     }
 
     /* preserve history within tmp if necessary */
-    if ( (dctxPtr->frameInfo.blockMode==LZ4F_blockLinked)
-      && (dctxPtr->dict != dctxPtr->tmpOutBuffer)
-      && (dctxPtr->dStage != dstage_getHeader)
+    if ( (dctx->frameInfo.blockMode==LZ4F_blockLinked)
+      && (dctx->dict != dctx->tmpOutBuffer)
+      && (dctx->dStage != dstage_getFrameHeader)
       && (!decompressOptionsPtr->stableDst)
-      && ((unsigned)(dctxPtr->dStage-1) < (unsigned)(dstage_getSuffix-1)) )
+      && ((unsigned)(dctx->dStage-1) < (unsigned)(dstage_getSuffix-1)) )
     {
-        if (dctxPtr->dStage == dstage_flushOut) {
-            size_t preserveSize = dctxPtr->tmpOut - dctxPtr->tmpOutBuffer;
-            size_t copySize = 64 KB - dctxPtr->tmpOutSize;
-            const BYTE* oldDictEnd = dctxPtr->dict + dctxPtr->dictSize - dctxPtr->tmpOutStart;
-            if (dctxPtr->tmpOutSize > 64 KB) copySize = 0;
+        if (dctx->dStage == dstage_flushOut) {
+            size_t preserveSize = dctx->tmpOut - dctx->tmpOutBuffer;
+            size_t copySize = 64 KB - dctx->tmpOutSize;
+            const BYTE* oldDictEnd = dctx->dict + dctx->dictSize - dctx->tmpOutStart;
+            if (dctx->tmpOutSize > 64 KB) copySize = 0;
             if (copySize > preserveSize) copySize = preserveSize;
 
-            memcpy(dctxPtr->tmpOutBuffer + preserveSize - copySize, oldDictEnd - copySize, copySize);
+            memcpy(dctx->tmpOutBuffer + preserveSize - copySize, oldDictEnd - copySize, copySize);
 
-            dctxPtr->dict = dctxPtr->tmpOutBuffer;
-            dctxPtr->dictSize = preserveSize + dctxPtr->tmpOutStart;
+            dctx->dict = dctx->tmpOutBuffer;
+            dctx->dictSize = preserveSize + dctx->tmpOutStart;
         } else {
-            size_t newDictSize = dctxPtr->dictSize;
-            const BYTE* oldDictEnd = dctxPtr->dict + dctxPtr->dictSize;
+            size_t newDictSize = dctx->dictSize;
+            const BYTE* oldDictEnd = dctx->dict + dctx->dictSize;
             if ((newDictSize) > 64 KB) newDictSize = 64 KB;
 
-            memcpy(dctxPtr->tmpOutBuffer, oldDictEnd - newDictSize, newDictSize);
+            memcpy(dctx->tmpOutBuffer, oldDictEnd - newDictSize, newDictSize);
 
-            dctxPtr->dict = dctxPtr->tmpOutBuffer;
-            dctxPtr->dictSize = newDictSize;
-            dctxPtr->tmpOut = dctxPtr->tmpOutBuffer + newDictSize;
+            dctx->dict = dctx->tmpOutBuffer;
+            dctx->dictSize = newDictSize;
+            dctx->tmpOut = dctx->tmpOutBuffer + newDictSize;
         }
     }
 
@@ -1584,17 +1653,17 @@ size_t LZ4F_decompress(LZ4F_dctx* dctxPtr,
  *  Dictionary is used "in place", without any preprocessing.
  *  It must remain accessible throughout the entire frame decoding.
  */
-size_t LZ4F_decompress_usingDict(LZ4F_dctx* dctxPtr,
+size_t LZ4F_decompress_usingDict(LZ4F_dctx* dctx,
                        void* dstBuffer, size_t* dstSizePtr,
                        const void* srcBuffer, size_t* srcSizePtr,
                        const void* dict, size_t dictSize,
                        const LZ4F_decompressOptions_t* decompressOptionsPtr)
 {
-    if (dctxPtr->dStage <= dstage_init) {
-        dctxPtr->dict = (const BYTE*)dict;
-        dctxPtr->dictSize = dictSize;
+    if (dctx->dStage <= dstage_init) {
+        dctx->dict = (const BYTE*)dict;
+        dctx->dictSize = dictSize;
     }
-    return LZ4F_decompress(dctxPtr, dstBuffer, dstSizePtr,
+    return LZ4F_decompress(dctx, dstBuffer, dstSizePtr,
                            srcBuffer, srcSizePtr,
                            decompressOptionsPtr);
 }
diff --git a/lib/lz4frame.h b/lib/lz4frame.h
index 844255b..88a6513 100644
--- a/lib/lz4frame.h
+++ b/lib/lz4frame.h
@@ -140,6 +140,11 @@ typedef enum {
 } LZ4F_contentChecksum_t;
 
 typedef enum {
+    LZ4F_noBlockChecksum=0,
+    LZ4F_blockChecksumEnabled
+} LZ4F_blockChecksum_t;
+
+typedef enum {
     LZ4F_frame=0,
     LZ4F_skippableFrame
     LZ4F_OBSOLETE_ENUM(skippableFrame)
@@ -153,23 +158,23 @@ typedef LZ4F_contentChecksum_t contentChecksum_t;
 #endif
 
 /*! LZ4F_frameInfo_t :
- * makes it possible to supply detailed frame parameters to the stream interface.
- * It's not required to set all fields, as long as the structure was initially memset() to zero.
- * All reserved fields must be set to zero. */
+ *  makes it possible to set or read frame parameters.
+ *  It's not required to set all fields, as long as the structure was initially memset() to zero.
+ *  For all fields, 0 sets it to default value */
 typedef struct {
   LZ4F_blockSizeID_t     blockSizeID;          /* max64KB, max256KB, max1MB, max4MB ; 0 == default */
-  LZ4F_blockMode_t       blockMode;            /* blockLinked, blockIndependent ; 0 == default */
-  LZ4F_contentChecksum_t contentChecksumFlag;  /* noContentChecksum, contentChecksumEnabled ; 0 == default  */
-  LZ4F_frameType_t       frameType;            /* LZ4F_frame, skippableFrame ; 0 == default */
+  LZ4F_blockMode_t       blockMode;            /* LZ4F_blockLinked, LZ4F_blockIndependent ; 0 == default */
+  LZ4F_contentChecksum_t contentChecksumFlag;  /* if enabled, frame is terminated with a 32-bits checksum of decompressed data ; 0 == disabled (default)  */
+  LZ4F_frameType_t       frameType;            /* read-only field : LZ4F_frame or LZ4F_skippableFrame */
   unsigned long long     contentSize;          /* Size of uncompressed content ; 0 == unknown */
   unsigned               dictID;               /* Dictionary ID, sent by the compressor to help decoder select the correct dictionary; 0 == no dictID provided */
-  unsigned               reserved[1];          /* must be zero for forward compatibility */
+  LZ4F_blockChecksum_t   blockChecksumFlag;    /* if enabled, each block is followed by a checksum of block's compressed data ; 0 == disabled (default)  */
 } LZ4F_frameInfo_t;
 
 /*! LZ4F_preferences_t :
- * makes it possible to supply detailed compression parameters to the stream interface.
- * It's not required to set all fields, as long as the structure was initially memset() to zero.
- * All reserved fields must be set to zero. */
+ *  makes it possible to supply detailed compression parameters to the stream interface.
+ *  It's not required to set all fields, as long as the structure was initially memset() to zero.
+ *  All reserved fields must be set to zero. */
 typedef struct {
   LZ4F_frameInfo_t frameInfo;
   int      compressionLevel;       /* 0 == default (fast mode); values above LZ4HC_CLEVEL_MAX count as LZ4HC_CLEVEL_MAX; values below 0 trigger "fast acceleration", proportional to value */
diff --git a/lib/lz4frame_static.h b/lib/lz4frame_static.h
index b585b72..1899f8e 100644
--- a/lib/lz4frame_static.h
+++ b/lib/lz4frame_static.h
@@ -59,7 +59,7 @@ extern "C" {
         ITEM(ERROR_contentChecksumFlag_invalid) \
         ITEM(ERROR_compressionLevel_invalid) \
         ITEM(ERROR_headerVersion_wrong) \
-        ITEM(ERROR_blockChecksum_unsupported) \
+        ITEM(ERROR_blockChecksum_invalid) \
         ITEM(ERROR_reservedFlag_set) \
         ITEM(ERROR_allocation_failed) \
         ITEM(ERROR_srcSize_tooLarge) \
diff --git a/tests/frametest.c b/tests/frametest.c
index d0665c5..88d0afd 100644
--- a/tests/frametest.c
+++ b/tests/frametest.c
@@ -402,7 +402,7 @@ int basicTests(U32 seed, double compressibility)
     CHECK_V(cSize, LZ4F_compressFrame(compressedBuffer, LZ4F_compressFrameBound(testSize, &prefs), CNBuffer, testSize, &prefs) );
     DISPLAYLEVEL(3, "Compressed %i bytes into a %i bytes frame \n", (int)testSize, (int)cSize);
 
-    DISPLAYLEVEL(3, "without checksum : ");
+    DISPLAYLEVEL(3, "without frame checksum : ");
     prefs.frameInfo.contentChecksumFlag = LZ4F_noContentChecksum;
     CHECK_V(cSize, LZ4F_compressFrame(compressedBuffer, LZ4F_compressFrameBound(testSize, &prefs), CNBuffer, testSize, &prefs) );
     DISPLAYLEVEL(3, "Compressed %i bytes into a %i bytes frame \n", (int)testSize, (int)cSize);
@@ -416,7 +416,7 @@ int basicTests(U32 seed, double compressibility)
         DISPLAYLEVEL(3, "Compressed %u bytes into a %u bytes frame \n", (U32)testSize, (U32)cSize);
     }
 
-    DISPLAYLEVEL(3, "without checksum : ");
+    DISPLAYLEVEL(3, "without frame checksum : ");
     prefs.frameInfo.contentChecksumFlag = LZ4F_noContentChecksum;
     {   size_t const dstCapacity = LZ4F_compressFrameBound(testSize, &prefs);
         DISPLAYLEVEL(4, "dstCapacity = %u  ; ", (U32)dstCapacity)
@@ -424,6 +424,29 @@ int basicTests(U32 seed, double compressibility)
         DISPLAYLEVEL(3, "Compressed %u bytes into a %u bytes frame \n", (U32)testSize, (U32)cSize);
     }
 
+    DISPLAYLEVEL(3, "LZ4F_compressFrame with block checksum : ");
+    memset(&prefs, 0, sizeof(prefs));
+    prefs.frameInfo.blockChecksumFlag = LZ4F_blockChecksumEnabled;
+    CHECK_V(cSize, LZ4F_compressFrame(compressedBuffer, LZ4F_compressFrameBound(testSize, &prefs), CNBuffer, testSize, &prefs) );
+    DISPLAYLEVEL(3, "Compressed %i bytes into a %i bytes frame \n", (int)testSize, (int)cSize);
+
+    DISPLAYLEVEL(3, "Decompress with block checksum : ");
+    {   size_t iSize = cSize;
+        size_t decodedSize = COMPRESSIBLE_NOISE_LENGTH;
+        LZ4F_decompressionContext_t dctx;
+        CHECK( LZ4F_createDecompressionContext(&dctx, LZ4F_VERSION) );
+        CHECK( LZ4F_decompress(dctx, decodedBuffer, &decodedSize, compressedBuffer, &iSize, NULL) );
+        if (decodedSize != testSize) goto _output_error;
+        if (iSize != cSize) goto _output_error;
+        {   U64 const crcDest = XXH64(decodedBuffer, decodedSize, 1);
+            U64 const crcSrc = XXH64(CNBuffer, testSize, 1);
+            if (crcDest != crcSrc) goto _output_error;
+        }
+        DISPLAYLEVEL(3, "Regenerated %u bytes \n", (U32)decodedSize);
+
+        CHECK( LZ4F_freeDecompressionContext(dctx) );
+    }
+
     /* frame content size tests */
     {   size_t cErr;
         BYTE* const ostart = (BYTE*)compressedBuffer;
@@ -771,6 +794,7 @@ int fuzzerTests(U32 seed, unsigned nbTests, unsigned startTest, double compressi
         memset(&prefs, 0, sizeof(prefs));
         prefs.frameInfo.blockMode = (LZ4F_blockMode_t)(FUZ_rand(&randState) & 1);
         prefs.frameInfo.blockSizeID = (LZ4F_blockSizeID_t)(4 + (FUZ_rand(&randState) & 3));
+        prefs.frameInfo.blockChecksumFlag = (LZ4F_blockChecksum_t)(FUZ_rand(&randState) & 1);
         prefs.frameInfo.contentChecksumFlag = (LZ4F_contentChecksum_t)(FUZ_rand(&randState) & 1);
         prefs.frameInfo.contentSize = ((FUZ_rand(&randState) & 0xF) == 1) ? srcSize : 0;
         prefs.autoFlush = neverFlush ? 0 : (FUZ_rand(&randState) & 7) == 2;
-- 
cgit v0.12


From 930a6921103c3ae4e62c99f86fd5329ef957900f Mon Sep 17 00:00:00 2001
From: Yann Collet <cyan@fb.com>
Date: Fri, 11 Aug 2017 17:58:46 -0700
Subject: cli : restored command -BX to enable block checksum (#322)

---
 programs/lz4cli.c |  2 +-
 programs/lz4io.c  | 11 ++++++-----
 tests/Makefile    |  1 +
 3 files changed, 8 insertions(+), 6 deletions(-)

diff --git a/programs/lz4cli.c b/programs/lz4cli.c
index 55f3133..dede834 100644
--- a/programs/lz4cli.c
+++ b/programs/lz4cli.c
@@ -144,7 +144,7 @@ static int usage_advanced(const char* exeName)
     DISPLAY( " -l     : compress using Legacy format (Linux kernel compression)\n");
     DISPLAY( " -B#    : Block size [4-7] (default : 7) \n");
     DISPLAY( " -BD    : Block dependency (improve compression ratio) \n");
-    /* DISPLAY( " -BX    : enable block checksum (default:disabled)\n");   *//* Option currently inactive */
+    DISPLAY( " -BX    : enable block checksum (default:disabled) \n");
     DISPLAY( "--no-frame-crc : disable stream checksum (default:enabled) \n");
     DISPLAY( "--content-size : compressed frame includes original size (default:not present)\n");
     DISPLAY( "--[no-]sparse  : sparse mode (default:enabled on file, disabled on stdout)\n");
diff --git a/programs/lz4io.c b/programs/lz4io.c
index 1e6b437..06741b4 100644
--- a/programs/lz4io.c
+++ b/programs/lz4io.c
@@ -173,17 +173,17 @@ int LZ4IO_setBlockMode(LZ4IO_blockMode_t blockMode)
     return g_blockIndependence;
 }
 
-/* Default setting : no checksum */
-int LZ4IO_setBlockChecksumMode(int xxhash)
+/* Default setting : no block checksum */
+int LZ4IO_setBlockChecksumMode(int enable)
 {
-    g_blockChecksum = (xxhash != 0);
+    g_blockChecksum = (enable != 0);
     return g_blockChecksum;
 }
 
 /* Default setting : checksum enabled */
-int LZ4IO_setStreamChecksumMode(int xxhash)
+int LZ4IO_setStreamChecksumMode(int enable)
 {
-    g_streamChecksum = (xxhash != 0);
+    g_streamChecksum = (enable != 0);
     return g_streamChecksum;
 }
 
@@ -455,6 +455,7 @@ static int LZ4IO_compressFilename_extRess(cRess_t ress, const char* srcFileName,
     prefs.compressionLevel = compressionLevel;
     prefs.frameInfo.blockMode = (LZ4F_blockMode_t)g_blockIndependence;
     prefs.frameInfo.blockSizeID = (LZ4F_blockSizeID_t)g_blockSizeId;
+    prefs.frameInfo.blockChecksumFlag = (LZ4F_blockChecksum_t)g_blockChecksum;
     prefs.frameInfo.contentChecksumFlag = (LZ4F_contentChecksum_t)g_streamChecksum;
     if (g_contentSizeFlag) {
       U64 const fileSize = UTIL_getFileSize(srcFileName);
diff --git a/tests/Makefile b/tests/Makefile
index 5d2532f..f00778f 100644
--- a/tests/Makefile
+++ b/tests/Makefile
@@ -263,6 +263,7 @@ test-lz4-basic: lz4 datagen unlz4 lz4cat
 	$(LZ4) -f tmp
 	cat tmp >> tmp.lz4
 	$(LZ4) -f tmp.lz4         # uncompress valid frame followed by invalid data
+	$(LZ4) -BX tmp -c -q | $(LZ4) -tv  # test block checksum
 	@$(RM) tmp*
 
 test-lz4-hugefile: lz4 datagen
-- 
cgit v0.12