From: Yann Collet <yann.collet.73@gmail.com>
Date: Fri, 7 Aug 2015 14:50:42 +0000 (+0100)
Subject: zstd_compress() no longer requires maxDstSize >= ZSTD_compressBound(srcSize)
X-Git-Tag: v0.1.0~2^2~15
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=96f3b2c0f76015a3f37228370096f333d86338db;p=thirdparty%2Fzstd.git

zstd_compress() no longer requires maxDstSize >= ZSTD_compressBound(srcSize)
---

diff --git a/lib/zstd.c b/lib/zstd.c
index afa44e334..181eaf8fa 100644
--- a/lib/zstd.c
+++ b/lib/zstd.c
@@ -547,7 +547,6 @@ static size_t ZSTD_compressLiterals (void* dst, size_t dstSize,
 {
     const size_t minGain = ZSTD_minGain(srcSize);
 
-#if 1
 #define LHSIZE 5
     BYTE* const ostart = (BYTE*)dst;
     size_t hsize = HUF_compress(ostart+LHSIZE, dstSize-LHSIZE, src, srcSize);
@@ -569,65 +568,6 @@ static size_t ZSTD_compressLiterals (void* dst, size_t dstSize,
 
     hsize -= 2;
     return hsize+LHSIZE;
-
-#else
-
-    const BYTE* const istart = (const BYTE*) src;
-    const BYTE* ip = istart;
-
-    BYTE* const ostart = (BYTE*) dst;
-    BYTE* op = ostart + ZSTD_blockHeaderSize;
-    BYTE* const oend = ostart + dstSize;
-
-    U32 maxSymbolValue = 256;
-    U32 tableLog = LitFSELog;
-    U32 count[256];
-    S16 norm[256];
-    U32 CTable[ FSE_CTABLE_SIZE_U32(LitFSELog, 256) ];
-    size_t errorCode;
-
-    /* early out */
-    if (dstSize < FSE_compressBound(srcSize)) return (size_t)-ZSTD_ERROR_maxDstSize_tooSmall;
-
-    /* Scan input and build symbol stats */
-    errorCode = FSE_count (count, &maxSymbolValue, ip, srcSize);
-    if (FSE_isError(errorCode)) return (size_t)-ZSTD_ERROR_GENERIC;
-    if (errorCode == srcSize) return 1;
-    if (errorCode < (srcSize >> 6)) return 0;   /* cheap heuristic : probably not compressible enough */
-
-    tableLog = FSE_optimalTableLog(tableLog, srcSize, maxSymbolValue);
-    errorCode = (int)FSE_normalizeCount (norm, tableLog, count, srcSize, maxSymbolValue);
-    if (FSE_isError(errorCode)) return (size_t)-ZSTD_ERROR_GENERIC;
-
-    /* Write table description header */
-    errorCode = FSE_writeNCount (op, FSE_MAX_HEADERSIZE, norm, maxSymbolValue, tableLog);
-    if (FSE_isError(errorCode)) return (size_t)-ZSTD_ERROR_GENERIC;
-    op += errorCode;
-
-    /* Compress */
-    errorCode = FSE_buildCTable (CTable, norm, maxSymbolValue, tableLog);
-    if (FSE_isError(errorCode)) return (size_t)-ZSTD_ERROR_GENERIC;
-    errorCode = ZSTD_compressLiterals_usingCTable(op, oend - op, ip, srcSize, CTable);
-    if (ZSTD_isError(errorCode)) return errorCode;
-    op += errorCode;
-
-    /* check compressibility */
-    if ( (size_t)(op-ostart) >= srcSize-minGain)
-        return 0;
-
-    /* Build header */
-    {
-        size_t totalSize;
-        totalSize  = op - ostart - ZSTD_blockHeaderSize;
-        ostart[0]  = (BYTE)(totalSize>>16);
-        ostart[1]  = (BYTE)(totalSize>>8);
-        ostart[2]  = (BYTE)totalSize;
-        ostart[0] += (BYTE)(bt_compressed<<6); /* is a block, is compressed */
-    }
-
-    return op-ostart;
-
-#endif // 1
 }
 
 
@@ -1066,7 +1006,6 @@ size_t ZSTD_compressContinue(ZSTD_Cctx*  cctx, void* dst, size_t maxDstSize, con
     const U32 updateRate = 2 * BLOCKSIZE;
 
     /*  Init */
-    if (maxDstSize < ZSTD_compressBound(srcSize) - 4 /* frame header size*/) return (size_t)-ZSTD_ERROR_maxDstSize_tooSmall;
     if (ctx->base==NULL)
         ctx->base = (const BYTE*)src, ctx->current=0, ctx->nextUpdate = g_maxDistance;
     if (src != ctx->base + ctx->current)   /* not contiguous */
diff --git a/lib/zstd.h b/lib/zstd.h
index 50ee72c43..1e20b4f18 100644
--- a/lib/zstd.h
+++ b/lib/zstd.h
@@ -46,8 +46,8 @@ extern "C" {
 *  Version
 **************************************/
 #define ZSTD_VERSION_MAJOR    0    /* for breaking interface changes  */
-#define ZSTD_VERSION_MINOR    0    /* for new (non-breaking) interface capabilities */
-#define ZSTD_VERSION_RELEASE  2    /* for tweaks, bug-fixes, or development */
+#define ZSTD_VERSION_MINOR    1    /* for new (non-breaking) interface capabilities */
+#define ZSTD_VERSION_RELEASE  0    /* for tweaks, bug-fixes, or development */
 #define ZSTD_VERSION_NUMBER  (ZSTD_VERSION_MAJOR *100*100 + ZSTD_VERSION_MINOR *100 + ZSTD_VERSION_RELEASE)
 unsigned ZSTD_versionNumber (void);
 
@@ -64,8 +64,8 @@ size_t ZSTD_decompress( void* dst, size_t maxOriginalSize,
 /*
 ZSTD_compress() :
     Compresses 'srcSize' bytes from buffer 'src' into buffer 'dst', of maximum size 'dstSize'.
-    Destination buffer should be sized to handle worst cases situations (input data not compressible).
-    Worst case size evaluation is provided by function ZSTD_compressBound().
+    Destination buffer must be already allocated.
+    Compression runs faster if maxDstSize >=  ZSTD_compressBound(srcSize).
     return : the number of bytes written into buffer 'dst'
              or an error code if it fails (which can be tested using ZSTD_isError())