minor lz4frame refactoring

2 files changed, 26 insertions, 37 deletions

diff --git a/lib/lz4.h b/lib/lz4.h
index f04344b..db55b11 100644
--- a/lib/lz4.h
+++ b/lib/lz4.h
@@ -45,7 +45,7 @@ extern "C" {
 */
 
 /**************************************
-   Version
+*  Version
 **************************************/
 #define LZ4_VERSION_MAJOR    1    /* for breaking interface changes  */
 #define LZ4_VERSION_MINOR    5    /* for new (non-breaking) interface capabilities */
@@ -54,7 +54,7 @@ extern "C" {
 int LZ4_versionNumber (void);
 
 /**************************************
-   Tuning parameter
+*  Tuning parameter
 **************************************/
 /*
  * LZ4_MEMORY_USAGE :
@@ -67,7 +67,7 @@ int LZ4_versionNumber (void);
 
 
 /**************************************
-   Simple Functions
+*  Simple Functions
 **************************************/
 
 int LZ4_compress        (const char* source, char* dest, int sourceSize);
@@ -96,7 +96,7 @@ LZ4_decompress_safe() :
 
 
 /**************************************
-   Advanced Functions
+*  Advanced Functions
 **************************************/
 #define LZ4_MAX_INPUT_SIZE        0x7E000000   /* 2 113 929 216 bytes */
 #define LZ4_COMPRESSBOUND(isize)  ((unsigned int)(isize) > (unsigned int)LZ4_MAX_INPUT_SIZE ? 0 : (isize) + ((isize)/255) + 16)
@@ -170,7 +170,7 @@ int LZ4_decompress_safe_partial (const char* source, char* dest, int compressedS
 
 
 /***********************************************
-   Streaming Compression Functions
+*  Streaming Compression Functions
 ***********************************************/
 
 #define LZ4_STREAMSIZE_U64 ((1 << (LZ4_MEMORY_USAGE-3)) + 4)
@@ -235,7 +235,7 @@ int LZ4_saveDict (LZ4_stream_t* LZ4_streamPtr, char* safeBuffer, int dictSize);
 
 
 /************************************************
-   Streaming Decompression Functions
+*  Streaming Decompression Functions
 ************************************************/
 
 #define LZ4_STREAMDECODESIZE_U64  4
@@ -286,7 +286,7 @@ int LZ4_decompress_fast_usingDict (const char* source, char* dest, int originalS
 
 
 /**************************************
-   Obsolete Functions
+*  Obsolete Functions
 **************************************/
 /*
 Obsolete decompression functions
diff --git a/lib/lz4frame.c b/lib/lz4frame.c
index d08cf94..ed47c0a 100644
--- a/lib/lz4frame.c
+++ b/lib/lz4frame.c
@@ -208,6 +208,21 @@ static BYTE LZ4F_headerChecksum (const BYTE* header, size_t length)
 /**************************************
 *  Simple compression functions
 **************************************/
+static blockSizeID_t LZ4F_optimalBSID(const blockSizeID_t requestedBSID, const size_t srcSize)
+{
+    blockSizeID_t proposedBSID = max64KB;
+    size_t maxBlockSize = 64 KB;
+    while (requestedBSID > proposedBSID)
+    {
+        if (srcSize <= maxBlockSize)
+            return proposedBSID;
+        proposedBSID = (blockSizeID_t)((int)proposedBSID + 1);
+        maxBlockSize <<= 2;
+    }
+    return requestedBSID;
+}
+
+
 size_t LZ4F_compressFrameBound(size_t srcSize, const LZ4F_preferences_t* preferencesPtr)
 {
     LZ4F_preferences_t prefs;
@@ -217,20 +232,7 @@ size_t LZ4F_compressFrameBound(size_t srcSize, const LZ4F_preferences_t* prefere
     if (preferencesPtr!=NULL) prefs = *preferencesPtr;
     else memset(&prefs, 0, sizeof(prefs));
 
-    {
-        blockSizeID_t proposedBSID = max64KB;
-        size_t maxBlockSize = 64 KB;
-        while (prefs.frameInfo.blockSizeID > proposedBSID)
-        {
-            if (srcSize <= maxBlockSize)
-            {
-                prefs.frameInfo.blockSizeID = proposedBSID;
-                break;
-            }
-            proposedBSID = (blockSizeID_t)( ((int)proposedBSID) + 1);
-            maxBlockSize <<= 2;
-        }
-    }
+    prefs.frameInfo.blockSizeID = LZ4F_optimalBSID(prefs.frameInfo.blockSizeID, srcSize);
     prefs.autoFlush = 1;
 
     headerSize = 7;      /* basic header size (no option) including magic number */
@@ -241,11 +243,11 @@ 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 v1.4.1, in a single step.
+* 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 be set to default.
+* 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())
 */
@@ -268,20 +270,7 @@ size_t LZ4F_compressFrame(void* dstBuffer, size_t dstMaxSize, const void* srcBuf
     if (preferencesPtr!=NULL) prefs = *preferencesPtr;
     else memset(&prefs, 0, sizeof(prefs));
 
-    {
-        blockSizeID_t proposedBSID = max64KB;
-        size_t maxBlockSize = 64 KB;
-        while (prefs.frameInfo.blockSizeID > proposedBSID)
-        {
-            if (srcSize <= maxBlockSize)
-            {
-                prefs.frameInfo.blockSizeID = proposedBSID;
-                break;
-            }
-            proposedBSID = (blockSizeID_t)((int)proposedBSID + 1);
-            maxBlockSize <<= 2;
-        }
-    }
+    prefs.frameInfo.blockSizeID = LZ4F_optimalBSID(prefs.frameInfo.blockSizeID, srcSize);
     prefs.autoFlush = 1;
     if (srcSize <= LZ4F_getBlockSize(prefs.frameInfo.blockSizeID))
         prefs.frameInfo.blockMode = blockIndependent;   /* no need for linked blocks */