ddidderr/zstd-rs
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zstd_compress() no longer requires maxDstSize >= ZSTD_compressBound(srcSize)

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This commit is contained in:
Yann Collet
2015-08-07 15:50:42 +01:00
parent a787550d1c
commit 96f3b2c0f7
2 changed files with 4 additions and 65 deletions
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lib/zstd.c
-61
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@@ -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 */
lib/zstd.h
+4 -4
View File
@@ -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())