Merge pull request #352 from lz4/resetDCtx

Reset decompression context

6 files changed, 150 insertions, 126 deletions

diff --git a/lib/Makefile b/lib/Makefile
index 9a794b8..c6fd7b8 100644
--- a/lib/Makefile
+++ b/lib/Makefile
@@ -46,10 +46,10 @@ BUILD_STATIC:= yes
 
 CPPFLAGS+= -DXXH_NAMESPACE=LZ4_
 CFLAGS  ?= -O3
-DEBUGFLAGS:=-g -Wall -Wextra -Wcast-qual -Wcast-align -Wshadow \
+DEBUGFLAGS:= -Wall -Wextra -Wcast-qual -Wcast-align -Wshadow \
            -Wswitch-enum -Wdeclaration-after-statement -Wstrict-prototypes -Wundef \
            -Wpointer-arith -Wstrict-aliasing=1
-CFLAGS  += $(MOREFLAGS)
+CFLAGS  += $(DEBUGFLAGS) $(MOREFLAGS)
 FLAGS    = $(CPPFLAGS) $(CFLAGS) $(LDFLAGS)
 
 
@@ -70,12 +70,13 @@ endif
 
 LIBLZ4 = liblz4.$(SHARED_EXT_VER)
 
+.PHONY: default
 default: lib-release
 
-lib-release: liblz4.a liblz4
+lib-release: DEBUGFLAGS :=
+lib-release: lib
 
-lib: CFLAGS += $(DEBUGFLAGS)
-lib: lib-release
+lib: liblz4.a liblz4
 
 all: lib
 
@@ -83,7 +84,7 @@ all32: CFLAGS+=-m32
 all32: all
 
 liblz4.a: *.c
-ifeq ($(BUILD_STATIC),yes)
+ifeq ($(BUILD_STATIC),yes)  # can be disabled on command line
 	@echo compiling static library
 	@$(CC) $(CPPFLAGS) $(CFLAGS) -c $^
 	@$(AR) rcs $@ *.o
diff --git a/lib/lz4.h b/lib/lz4.h
index d5a3016..5b6bc92 100644
--- a/lib/lz4.h
+++ b/lib/lz4.h
@@ -88,8 +88,8 @@ extern "C" {
 
 /*------   Version   ------*/
 #define LZ4_VERSION_MAJOR    1    /* for breaking interface changes  */
-#define LZ4_VERSION_MINOR    7    /* for new (non-breaking) interface capabilities */
-#define LZ4_VERSION_RELEASE  6    /* for tweaks, bug-fixes, or development */
+#define LZ4_VERSION_MINOR    8    /* for new (non-breaking) interface capabilities */
+#define LZ4_VERSION_RELEASE  0    /* for tweaks, bug-fixes, or development */
 
 #define LZ4_VERSION_NUMBER (LZ4_VERSION_MAJOR *100*100 + LZ4_VERSION_MINOR *100 + LZ4_VERSION_RELEASE)
 
diff --git a/lib/lz4frame.c b/lib/lz4frame.c
index 356be8a..fb37789 100644
--- a/lib/lz4frame.c
+++ b/lib/lz4frame.c
@@ -209,7 +209,8 @@ LZ4F_errorCodes LZ4F_getErrorCode(size_t functionResult)
 
 static LZ4F_errorCode_t err0r(LZ4F_errorCodes code)
 {
-    LZ4_STATIC_ASSERT(sizeof(ptrdiff_t) >= sizeof(size_t));    /* A compilation error here means sizeof(ptrdiff_t) is not large enough */
+    /* A compilation error here means sizeof(ptrdiff_t) is not large enough */
+    LZ4_STATIC_ASSERT(sizeof(ptrdiff_t) >= sizeof(size_t));
     return (LZ4F_errorCode_t)-(ptrdiff_t)code;
 }
 
@@ -241,7 +242,8 @@ static BYTE LZ4F_headerChecksum (const void* header, size_t length)
 /*-************************************
 *  Simple-pass compression functions
 **************************************/
-static LZ4F_blockSizeID_t LZ4F_optimalBSID(const LZ4F_blockSizeID_t requestedBSID, const size_t srcSize)
+static LZ4F_blockSizeID_t LZ4F_optimalBSID(const LZ4F_blockSizeID_t requestedBSID,
+                                           const size_t srcSize)
 {
     LZ4F_blockSizeID_t proposedBSID = LZ4F_max64KB;
     size_t maxBlockSize = 64 KB;
@@ -256,11 +258,13 @@ static LZ4F_blockSizeID_t LZ4F_optimalBSID(const LZ4F_blockSizeID_t requestedBSI
 
 /* LZ4F_compressBound() :
  * Provides dstCapacity given a srcSize to guarantee operation success in worst case situations.
- * prefsPtr is optional : you can provide NULL as argument, preferences will be set to cover worst case scenario.
- * Result is always the same for a srcSize and prefsPtr, so it can be trusted to size reusable buffers.
+ * 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.
  */
-static size_t LZ4F_compressBound_internal(size_t srcSize, const LZ4F_preferences_t* preferencesPtr, size_t alreadyBuffered)
+static size_t LZ4F_compressBound_internal(size_t srcSize,
+                                    const LZ4F_preferences_t* preferencesPtr,
+                                          size_t alreadyBuffered)
 {
     LZ4F_preferences_t prefsNull;
     memset(&prefsNull, 0, sizeof(prefsNull));
@@ -298,14 +302,14 @@ 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 (dstMaxSize) to ensure compression completion even in worst case.
-* You can get the minimum value of dstMaxSize by using 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 then 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())
-*/
+ *  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())
+ */
 size_t LZ4F_compressFrame(void* dstBuffer, size_t dstCapacity, const void* srcBuffer, size_t srcSize, const LZ4F_preferences_t* preferencesPtr)
 {
     LZ4F_cctx_t cctxI;
@@ -404,10 +408,10 @@ 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())
+ *  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())
  */
 size_t LZ4F_compressBegin(LZ4F_cctx* cctxPtr, void* dstBuffer, size_t dstCapacity, const LZ4F_preferences_t* preferencesPtr)
 {
@@ -650,13 +654,13 @@ size_t LZ4F_compressUpdate(LZ4F_cctx* cctxPtr, void* dstBuffer, size_t dstCapaci
 
 
 /*! LZ4F_flush() :
-* Should you need to create compressed data immediately, without waiting for a block to be filled,
-* you can call LZ4_flush(), which will immediately compress any remaining data stored within compressionContext.
-* The result of the function is the number of bytes written into dstBuffer
-* (it can be zero, this means there was no data left within compressionContext)
-* The function outputs an error code if it fails (can be tested using LZ4F_isError())
-* The LZ4F_compressOptions_t structure is optional : you can provide NULL as argument.
-*/
+ *  Should you need to create compressed data immediately, without waiting for a block to be filled,
+ *  you can call LZ4_flush(), which will immediately compress any remaining data stored within compressionContext.
+ *  The result of the function is the number of bytes written into dstBuffer
+ *  (it can be zero, this means there was no data left within compressionContext)
+ *  The function outputs an error code if it fails (can be tested using LZ4F_isError())
+ *  The LZ4F_compressOptions_t structure is optional : you can provide NULL as argument.
+ */
 size_t LZ4F_flush(LZ4F_cctx* cctxPtr, void* dstBuffer, size_t dstCapacity, const LZ4F_compressOptions_t* compressOptionsPtr)
 {
     BYTE* const dstStart = (BYTE*)dstBuffer;
@@ -687,14 +691,14 @@ size_t LZ4F_flush(LZ4F_cctx* cctxPtr, void* dstBuffer, size_t dstCapacity, const
 
 
 /*! LZ4F_compressEnd() :
-* When you want to properly finish the compressed frame, just call LZ4F_compressEnd().
-* It will flush whatever data remained within compressionContext (like LZ4_flush())
-* but also properly finalize the frame, with an endMark and a checksum.
-* The result of the function is the number of bytes written into dstBuffer (necessarily >= 4 (endMark size))
-* The function outputs an error code if it fails (can be tested using LZ4F_isError())
-* The LZ4F_compressOptions_t structure is optional : you can provide NULL as argument.
-* compressionContext can then be used again, starting with LZ4F_compressBegin(). The preferences will remain the same.
-*/
+ * When you want to properly finish the compressed frame, just call LZ4F_compressEnd().
+ * It will flush whatever data remained within compressionContext (like LZ4_flush())
+ * but also properly finalize the frame, with an endMark and a checksum.
+ * The result of the function is the number of bytes written into dstBuffer (necessarily >= 4 (endMark size))
+ * The function outputs an error code if it fails (can be tested using LZ4F_isError())
+ * The LZ4F_compressOptions_t structure is optional : you can provide NULL as argument.
+ * compressionContext can then be used again, starting with LZ4F_compressBegin(). The preferences will remain the same.
+ */
 size_t LZ4F_compressEnd(LZ4F_cctx* cctxPtr, void* dstBuffer, size_t dstMaxSize, const LZ4F_compressOptions_t* compressOptionsPtr)
 {
     BYTE* const dstStart = (BYTE*)dstBuffer;
@@ -751,11 +755,11 @@ struct LZ4F_dctx_s {
 
 
 /*! 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));
@@ -794,17 +798,16 @@ typedef enum {
     dstage_skipSkippable
 } dStage_t;
 
-LZ4F_errorCode_t LZ4F_resetDecompressionContext(LZ4F_dctx* dctx)
+void LZ4F_resetDecompressionContext(LZ4F_dctx* dctx)
 {
     dctx->dStage = dstage_getHeader;
-    return 0;
 }
 
 
 /*! LZ4F_headerSize() :
-*   @return : size of frame header
-*             or an error code, which can be tested using LZ4F_isError()
-*/
+ *   @return : size of frame header
+ *             or an error code, which can be tested using LZ4F_isError()
+ */
 static size_t LZ4F_headerSize(const void* src, size_t srcSize)
 {
     /* minimal srcSize to determine header size */
@@ -825,13 +828,13 @@ 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.
-             Also allocates internal buffers.
-   @return : nb Bytes read from src (necessarily <= srcSize)
-             or an error code (testable with LZ4F_isError())
-*/
+ *  input   : `src` points at the **beginning of the frame**
+ *  output  : set internal values of dctx, such as
+ *            dctxPtr->frameInfo and dctxPtr->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)
 {
     unsigned blockMode, contentSizeFlag, contentChecksumFlag, blockSizeID;
@@ -913,8 +916,8 @@ static size_t LZ4F_decodeHeader(LZ4F_dctx* dctxPtr, const void* src, size_t srcS
 
 
 /*! LZ4F_getFrameInfo() :
- * This function extracts frame parameters (such as max blockSize, frame checksum, etc.).
- * Its usage is optional. The objective is to provide relevant information for allocation purposes.
+ * 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.
@@ -935,7 +938,8 @@ LZ4F_errorCode_t LZ4F_getFrameInfo(LZ4F_dctx* dctxPtr, LZ4F_frameInfo_t* frameIn
         size_t o=0, i=0;
         *srcSizePtr = 0;
         *frameInfoPtr = dctxPtr->frameInfo;
-        return LZ4F_decompress(dctxPtr, NULL, &o, NULL, &i, NULL);  /* returns : recommended nb of bytes for LZ4F_decompress() */
+        /* returns : recommended nb of bytes for LZ4F_decompress() */
+        return LZ4F_decompress(dctxPtr, NULL, &o, NULL, &i, NULL);
     } else {
         if (dctxPtr->dStage == dstage_storeHeader) {
             /* frame decoding already started, in the middle of header => automatic fail */
@@ -945,7 +949,10 @@ LZ4F_errorCode_t LZ4F_getFrameInfo(LZ4F_dctx* dctxPtr, LZ4F_frameInfo_t* frameIn
             size_t decodeResult;
             size_t const hSize = LZ4F_headerSize(srcBuffer, *srcSizePtr);
             if (LZ4F_isError(hSize)) { *srcSizePtr=0; return hSize; }
-            if (*srcSizePtr < hSize) { *srcSizePtr=0; return err0r(LZ4F_ERROR_frameHeader_incomplete); }
+            if (*srcSizePtr < hSize) {
+                *srcSizePtr=0;
+                return err0r(LZ4F_ERROR_frameHeader_incomplete);
+            }
 
             decodeResult = LZ4F_decodeHeader(dctxPtr, srcBuffer, hSize);
             if (LZ4F_isError(decodeResult)) {
@@ -961,10 +968,15 @@ LZ4F_errorCode_t LZ4F_getFrameInfo(LZ4F_dctx* dctxPtr, LZ4F_frameInfo_t* frameIn
 
 
 /* trivial redirector, for common prototype */
-static int LZ4F_decompress_safe (const char* source, char* dest, int compressedSize, int maxDecompressedSize, const char* dictStart, int dictSize)
+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 (source, dest, compressedSize, maxDecompressedSize);
+    return LZ4_decompress_safe (src, dst, compressedSize, dstCapacity);
 }
 
 
@@ -1028,22 +1040,22 @@ 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.
-*
-* 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 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().
-*/
+ * 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.
+ *
+ * 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 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().
+ */
 size_t LZ4F_decompress(LZ4F_dctx* dctxPtr,
                        void* dstBuffer, size_t* dstSizePtr,
                        const void* srcBuffer, size_t* srcSizePtr,
@@ -1097,7 +1109,7 @@ size_t LZ4F_decompress(LZ4F_dctx* dctxPtr,
                     doAnotherStage = 0;   /* not enough src data, ask for some more */
                     break;
                 }
-                {   LZ4F_errorCode_t const hSize = LZ4F_decodeHeader(dctxPtr, dctxPtr->header, dctxPtr->tmpInTarget);
+                {   LZ4F_errorCode_t const hSize = LZ4F_decodeHeader(dctxPtr, dctxPtr->header, dctxPtr->tmpInTarget);  /* will change dStage appropriately */
                     if (LZ4F_isError(hSize)) return hSize;
                 }
                 break;
@@ -1145,7 +1157,7 @@ size_t LZ4F_decompress(LZ4F_dctx* dctxPtr,
                 memcpy(dctxPtr->tmpIn + dctxPtr->tmpInSize, srcPtr, sizeToCopy);
                 srcPtr += sizeToCopy;
                 dctxPtr->tmpInSize += sizeToCopy;
-                if (dctxPtr->tmpInSize < BHSize) {   /* not enough input to get full cBlockSize; wait for more */
+                if (dctxPtr->tmpInSize < BHSize) {   /* not enough input for cBlockSize */
                     nextSrcSizeHint = BHSize - dctxPtr->tmpInSize;
                     doAnotherStage  = 0;
                     break;
@@ -1153,13 +1165,14 @@ size_t LZ4F_decompress(LZ4F_dctx* dctxPtr,
                 selectedIn = dctxPtr->tmpIn;
             }
 
-        /* case dstage_decodeCBlockSize: */   /* no more direct access, to prevent scan-build warning */
+        /* case dstage_decodeCBlockSize: */   /* no more direct access, to remove scan-build warning */
             {   size_t const nextCBlockSize = LZ4F_readLE32(selectedIn) & 0x7FFFFFFFU;
                 if (nextCBlockSize==0) {  /* frameEnd signal, no more CBlock */
                     dctxPtr->dStage = dstage_getSuffix;
                     break;
                 }
-                if (nextCBlockSize > dctxPtr->maxBlockSize) return err0r(LZ4F_ERROR_GENERIC);   /* invalid cBlockSize */
+                if (nextCBlockSize > dctxPtr->maxBlockSize)
+                    return err0r(LZ4F_ERROR_maxBlockSize_invalid);
                 dctxPtr->tmpInTarget = nextCBlockSize;
                 if (LZ4F_readLE32(selectedIn) & LZ4F_BLOCKUNCOMPRESSED_FLAG) {
                     dctxPtr->dStage = dstage_copyDirect;
@@ -1175,11 +1188,13 @@ size_t LZ4F_decompress(LZ4F_dctx* dctxPtr,
 
         case dstage_copyDirect:   /* uncompressed block */
             {   size_t sizeToCopy = dctxPtr->tmpInTarget;
-                if ((size_t)(srcEnd-srcPtr) < sizeToCopy) sizeToCopy = srcEnd - srcPtr;  /* not enough input to read full block */
+                if ((size_t)(srcEnd-srcPtr) < sizeToCopy) sizeToCopy = srcEnd - srcPtr;
                 if ((size_t)(dstEnd-dstPtr) < sizeToCopy) sizeToCopy = dstEnd - dstPtr;
                 memcpy(dstPtr, srcPtr, sizeToCopy);
-                if (dctxPtr->frameInfo.contentChecksumFlag) XXH32_update(&(dctxPtr->xxh), srcPtr, sizeToCopy);
-                if (dctxPtr->frameInfo.contentSize) dctxPtr->frameRemainingSize -= sizeToCopy;
+                if (dctxPtr->frameInfo.contentChecksumFlag)
+                    XXH32_update(&(dctxPtr->xxh), srcPtr, sizeToCopy);
+                if (dctxPtr->frameInfo.contentSize)
+                    dctxPtr->frameRemainingSize -= sizeToCopy;
 
                 /* dictionary management */
                 if (dctxPtr->frameInfo.blockMode==LZ4F_blockLinked)
@@ -1240,10 +1255,14 @@ size_t LZ4F_decompress(LZ4F_dctx* dctxPtr,
                 else
                     decoder = LZ4F_decompress_safe;
 
-                decodedSize = decoder((const char*)selectedIn, (char*)dstPtr, (int)dctxPtr->tmpInTarget, (int)dctxPtr->maxBlockSize, (const char*)dctxPtr->dict, (int)dctxPtr->dictSize);
+                decodedSize = decoder((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 */
-                if (dctxPtr->frameInfo.contentChecksumFlag) XXH32_update(&(dctxPtr->xxh), dstPtr, decodedSize);
-                if (dctxPtr->frameInfo.contentSize) dctxPtr->frameRemainingSize -= decodedSize;
+                if (dctxPtr->frameInfo.contentChecksumFlag)
+                    XXH32_update(&(dctxPtr->xxh), dstPtr, decodedSize);
+                if (dctxPtr->frameInfo.contentSize)
+                    dctxPtr->frameRemainingSize -= decodedSize;
 
                 /* dictionary management */
                 if (dctxPtr->frameInfo.blockMode==LZ4F_blockLinked)
@@ -1280,10 +1299,15 @@ size_t LZ4F_decompress(LZ4F_dctx* dctxPtr,
                 }
 
                 /* Decode */
-                decodedSize = decoder((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;
+                decodedSize = decoder((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;
@@ -1314,7 +1338,8 @@ size_t LZ4F_decompress(LZ4F_dctx* dctxPtr,
 
         case dstage_getSuffix:
             {   size_t const suffixSize = dctxPtr->frameInfo.contentChecksumFlag * 4;
-                if (dctxPtr->frameRemainingSize) return err0r(LZ4F_ERROR_frameSize_wrong);   /* incorrect frame size decoded */
+                if (dctxPtr->frameRemainingSize)
+                    return err0r(LZ4F_ERROR_frameSize_wrong);   /* incorrect frame size decoded */
                 if (suffixSize == 0) {  /* frame completed */
                     nextSrcSizeHint = 0;
                     dctxPtr->dStage = dstage_getHeader;
@@ -1375,7 +1400,8 @@ size_t LZ4F_decompress(LZ4F_dctx* dctxPtr,
                 memcpy(dctxPtr->header + dctxPtr->tmpInSize, srcPtr, sizeToCopy);
                 srcPtr += sizeToCopy;
                 dctxPtr->tmpInSize += sizeToCopy;
-                if (dctxPtr->tmpInSize < dctxPtr->tmpInTarget) { /* not enough input to get full sBlockSize; wait for more */
+                if (dctxPtr->tmpInSize < dctxPtr->tmpInTarget) {
+                    /* not enough input to get full sBlockSize; wait for more */
                     nextSrcSizeHint = dctxPtr->tmpInTarget - dctxPtr->tmpInSize;
                     doAnotherStage = 0;
                     break;
diff --git a/lib/lz4frame.h b/lib/lz4frame.h
index 2e79a17..b1719e2 100644
--- a/lib/lz4frame.h
+++ b/lib/lz4frame.h
@@ -363,6 +363,14 @@ LZ4FLIB_API size_t LZ4F_decompress(LZ4F_dctx* dctx,
                                    const LZ4F_decompressOptions_t* dOptPtr);
 
 
+/*! LZ4F_resetDecompressionContext() : v1.8.0
+ *  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. */
+LZ4FLIB_API void LZ4F_resetDecompressionContext(LZ4F_dctx* dctx);   /* always successful */
+
+
 
 #if defined (__cplusplus)
 }
diff --git a/lib/lz4frame_static.h b/lib/lz4frame_static.h
index 8ea496d..d3bae82 100644
--- a/lib/lz4frame_static.h
+++ b/lib/lz4frame_static.h
@@ -50,15 +50,6 @@ extern "C" {
 #include "lz4frame.h"
 
 
-/* ---   Experimental functions   --- */
-/* LZ4F_resetDecompressionContext() :
- * LZ4F_decompress() does not guarantee to leave dctx in clean state in case of errors.
- * In order to re-use a dctx after a decompression error,
- * use LZ4F_resetDecompressionContext() first.
- * dctx will be able to start decompression on a new frame */
-LZ4FLIB_API LZ4F_errorCode_t LZ4F_resetDecompressionContext(LZ4F_dctx* dctx);
-
-
 /* ---   Error List   --- */
 #define LZ4F_LIST_ERRORS(ITEM) \
         ITEM(OK_NoError) \
diff --git a/lib/lz4hc.c b/lib/lz4hc.c
index 16fe029..b987d39 100644
--- a/lib/lz4hc.c
+++ b/lib/lz4hc.c
@@ -69,9 +69,9 @@
 
 
 /*===   Macros   ===*/
-#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(p)        chainTable[(U16)(p)]   /* faster */
+#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 */
 
 static U32 LZ4HC_hashPtr(const void* ptr) { return HASH_FUNCTION(LZ4_read32(ptr)); }
 
@@ -106,7 +106,7 @@ FORCE_INLINE void LZ4HC_Insert (LZ4HC_CCtx_internal* hc4, const BYTE* ip)
         U32 const h = LZ4HC_hashPtr(base+idx);
         size_t delta = idx - hashTable[h];
         if (delta>MAX_DISTANCE) delta = MAX_DISTANCE;
-        DELTANEXTU16(idx) = (U16)delta;
+        DELTANEXTU16(chainTable, idx) = (U16)delta;
         hashTable[h] = idx;
         idx++;
     }
@@ -115,8 +115,8 @@ FORCE_INLINE void LZ4HC_Insert (LZ4HC_CCtx_internal* hc4, const BYTE* ip)
 }
 
 
-FORCE_INLINE int LZ4HC_InsertAndFindBestMatch (LZ4HC_CCtx_internal* hc4,   /* Index table will be updated */
-                                               const BYTE* ip, const BYTE* const iLimit,
+FORCE_INLINE int LZ4HC_InsertAndFindBestMatch (LZ4HC_CCtx_internal* const hc4,   /* Index table will be updated */
+                                               const BYTE* const ip, const BYTE* const iLimit,
                                                const BYTE** matchpos,
                                                const int maxNbAttempts)
 {
@@ -138,8 +138,8 @@ FORCE_INLINE int LZ4HC_InsertAndFindBestMatch (LZ4HC_CCtx_internal* hc4,   /* In
         nbAttempts--;
         if (matchIndex >= dictLimit) {
             const BYTE* const match = base + matchIndex;
-            if (*(match+ml) == *(ip+ml)
-                && (LZ4_read32(match) == LZ4_read32(ip)))
+            if ( (*(match+ml) == *(ip+ml))   /* can be longer */
+               && (LZ4_read32(match) == LZ4_read32(ip)) )
             {
                 size_t const mlt = LZ4_count(ip+MINMATCH, match+MINMATCH, iLimit) + MINMATCH;
                 if (mlt > ml) { ml = mlt; *matchpos = match; }
@@ -156,7 +156,7 @@ FORCE_INLINE int LZ4HC_InsertAndFindBestMatch (LZ4HC_CCtx_internal* hc4,   /* In
                 if (mlt > ml) { ml = mlt; *matchpos = base + matchIndex; }   /* virtual matchpos */
             }
         }
-        matchIndex -= DELTANEXTU16(matchIndex);
+        matchIndex -= DELTANEXTU16(chainTable, matchIndex);
     }
 
     return (int)ml;
@@ -180,9 +180,9 @@ FORCE_INLINE int LZ4HC_InsertAndGetWiderMatch (
     const BYTE* const lowPrefixPtr = base + dictLimit;
     const U32 lowLimit = (hc4->lowLimit + 64 KB > (U32)(ip-base)) ? hc4->lowLimit : (U32)(ip - base) - (64 KB - 1);
     const BYTE* const dictBase = hc4->dictBase;
-    U32   matchIndex;
+    int const delta = (int)(ip-iLowLimit);
     int nbAttempts = maxNbAttempts;
-    int delta = (int)(ip-iLowLimit);
+    U32   matchIndex;
 
 
     /* First Match */
@@ -206,14 +206,14 @@ FORCE_INLINE int LZ4HC_InsertAndGetWiderMatch (
                     mlt -= back;
 
                     if (mlt > longest) {
-                        longest = (int)mlt;
+                        longest = mlt;
                         *matchpos = matchPtr+back;
                         *startpos = ip+back;
             }   }   }
         } else {
             const BYTE* const matchPtr = dictBase + matchIndex;
             if (LZ4_read32(matchPtr) == LZ4_read32(ip)) {
-                size_t mlt;
+                int mlt;
                 int back=0;
                 const BYTE* vLimit = ip + (dictLimit - matchIndex);
                 if (vLimit > iHighLimit) vLimit = iHighLimit;
@@ -222,10 +222,10 @@ FORCE_INLINE int LZ4HC_InsertAndGetWiderMatch (
                     mlt += LZ4_count(ip+mlt, base+dictLimit, iHighLimit);
                 while ((ip+back > iLowLimit) && (matchIndex+back > lowLimit) && (ip[back-1] == matchPtr[back-1])) back--;
                 mlt -= back;
-                if ((int)mlt > longest) { longest = (int)mlt; *matchpos = base + matchIndex + back; *startpos = ip+back; }
+                if (mlt > longest) { longest = mlt; *matchpos = base + matchIndex + back; *startpos = ip+back; }
             }
         }
-        matchIndex -= DELTANEXTU16(matchIndex);
+        matchIndex -= DELTANEXTU16(chainTable, matchIndex);
     }
 
     return longest;
@@ -238,12 +238,10 @@ typedef enum {
     limitedDestSize = 2,
 } limitedOutput_directive;
 
-#define LZ4HC_DEBUG 0
-#if LZ4HC_DEBUG
-static unsigned debug = 0;
+#ifndef LZ4HC_DEBUG
+#  define LZ4HC_DEBUG 0
 #endif
 
-
 /* LZ4HC_encodeSequence() :
  * @return : 0 if ok,
  *           1 if buffer issue detected */
@@ -257,15 +255,15 @@ FORCE_INLINE int LZ4HC_encodeSequence (
     BYTE* oend)
 {
     size_t length;
-    BYTE* token;
+    BYTE* const token = (*op)++;
 
 #if LZ4HC_DEBUG
-    if (debug) printf("literal : %u  --  match : %u  --  offset : %u\n", (U32)(*ip - *anchor), (U32)matchLength, (U32)(*ip-match));
+    printf("literal : %u  --  match : %u  --  offset : %u\n",
+           (U32)(*ip - *anchor), (U32)matchLength, (U32)(*ip-match));
 #endif
 
     /* Encode Literal length */
     length = (size_t)(*ip - *anchor);
-    token = (*op)++;
     if ((limit) && ((*op + (length >> 8) + length + (2 + 1 + LASTLITERALS)) > oend)) return 1;   /* Check output limit */
     if (length >= RUN_MASK) {
         size_t len = length - RUN_MASK;