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Improved speed of ZSTD_decompressStream()

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When ZSTD_decompressStream() detects
that there is enough space in dst
to complete decompression in a single pass,
delegates to ZSTD_decompress(),
for an extra ~5% speed boost
This commit is contained in:
Yann Collet 2017-02-28 00:14:28 -08:00
parent 1d7f30f9d4
commit d1760113ec
1 changed files with 15 additions and 1 deletions
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16
lib/decompress/zstd_decompress.c
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@ -2100,7 +2100,7 @@ size_t ZSTD_decompress_usingDDict(ZSTD_DCtx* dctx,
{ {
/* pass content and size in case legacy frames are encountered */ /* pass content and size in case legacy frames are encountered */
return ZSTD_decompressMultiFrame(dctx, dst, dstCapacity, src, srcSize, return ZSTD_decompressMultiFrame(dctx, dst, dstCapacity, src, srcSize,
ddict->dictContent, ddict->dictSize, NULL, 0,
ddict); ddict);
} }
@ -2301,6 +2301,20 @@ size_t ZSTD_decompressStream(ZSTD_DStream* zds, ZSTD_outBuffer* output, ZSTD_inB
break; break;
} } } }
/* check for single-pass mode opportunity */
if (zds->fParams.frameContentSize
&& (U64)(size_t)(oend-op) >= zds->fParams.frameContentSize) {
size_t const cSize = ZSTD_findFrameCompressedSize(istart, iend-istart);
if (cSize <= (size_t)(iend-istart)) {
size_t const decompressedSize = ZSTD_decompress_usingDDict(zds->dctx, op, oend-op, istart, cSize, zds->ddict);
if (ZSTD_isError(decompressedSize)) return decompressedSize;
ip += cSize;
op += decompressedSize;
zds->stage = zdss_init;
someMoreWork = 0;
break;
} }
/* Consume header */ /* Consume header */
ZSTD_refDDict(zds->dctx, zds->ddict); ZSTD_refDDict(zds->dctx, zds->ddict);
{ size_t const h1Size = ZSTD_nextSrcSizeToDecompress(zds->dctx); /* == ZSTD_frameHeaderSize_prefix */ { size_t const h1Size = ZSTD_nextSrcSizeToDecompress(zds->dctx); /* == ZSTD_frameHeaderSize_prefix */