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 */