ddidderr/zstd-rs
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added comments to better understand enforceMaxDist()

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This commit is contained in:
Yann Collet
2019-05-28 13:15:48 -07:00
parent 21bb78e908
commit 4baecdf72a
3 changed files with 79 additions and 58 deletions
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lib/compress/zstd_compress.c
+15 -16
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@@ -1282,8 +1282,8 @@ static void ZSTD_reset_compressedBlockState(ZSTD_compressedBlockState_t* bs)
}
/*! ZSTD_invalidateMatchState()
* Invalidate all the matches in the match finder tables.
* Requires nextSrc and base to be set (can be NULL).
* Invalidate all the matches in the match finder tables.
* Requires nextSrc and base to be set (can be NULL).
*/
static void ZSTD_invalidateMatchState(ZSTD_matchState_t* ms)
{
@@ -1587,15 +1587,14 @@ static int ZSTD_shouldAttachDict(const ZSTD_CDict* cdict,
* handled in _enforceMaxDist */
}
static size_t ZSTD_resetCCtx_byAttachingCDict(
ZSTD_CCtx* cctx,
const ZSTD_CDict* cdict,
ZSTD_CCtx_params params,
U64 pledgedSrcSize,
ZSTD_buffered_policy_e zbuff)
static size_t
ZSTD_resetCCtx_byAttachingCDict(ZSTD_CCtx* cctx,
const ZSTD_CDict* cdict,
ZSTD_CCtx_params params,
U64 pledgedSrcSize,
ZSTD_buffered_policy_e zbuff)
{
{
const ZSTD_compressionParameters *cdict_cParams = &cdict->matchState.cParams;
{ const ZSTD_compressionParameters* const cdict_cParams = &cdict->matchState.cParams;
unsigned const windowLog = params.cParams.windowLog;
assert(windowLog != 0);
/* Resize working context table params for input only, since the dict
@@ -1607,8 +1606,7 @@ static size_t ZSTD_resetCCtx_byAttachingCDict(
assert(cctx->appliedParams.cParams.strategy == cdict_cParams->strategy);
}
{
const U32 cdictEnd = (U32)( cdict->matchState.window.nextSrc
{ const U32 cdictEnd = (U32)( cdict->matchState.window.nextSrc
- cdict->matchState.window.base);
const U32 cdictLen = cdictEnd - cdict->matchState.window.dictLimit;
if (cdictLen == 0) {
@@ -1625,9 +1623,9 @@ static size_t ZSTD_resetCCtx_byAttachingCDict(
cctx->blockState.matchState.window.base + cdictEnd;
ZSTD_window_clear(&cctx->blockState.matchState.window);
}
/* loadedDictEnd is expressed within the referential of the active context */
cctx->blockState.matchState.loadedDictEnd = cctx->blockState.matchState.window.dictLimit;
}
}
} }
cctx->dictID = cdict->dictID;
@@ -2844,7 +2842,7 @@ static size_t ZSTD_compress_frameChunk (ZSTD_CCtx* cctx,
BYTE* const ostart = (BYTE*)dst;
BYTE* op = ostart;
U32 const maxDist = (U32)1 << cctx->appliedParams.cParams.windowLog;
assert(cctx->appliedParams.cParams.windowLog <= 31);
assert(cctx->appliedParams.cParams.windowLog <= ZSTD_WINDOWLOG_MAX);
DEBUGLOG(5, "ZSTD_compress_frameChunk (blockSize=%u)", (unsigned)blockSize);
if (cctx->appliedParams.fParams.checksumFlag && srcSize)
@@ -2899,7 +2897,7 @@ static size_t ZSTD_compress_frameChunk (ZSTD_CCtx* cctx,
} }
if (lastFrameChunk && (op>ostart)) cctx->stage = ZSTDcs_ending;
return op-ostart;
return (size_t)(op-ostart);
}
@@ -2991,6 +2989,7 @@ static size_t ZSTD_compressContinue_internal (ZSTD_CCtx* cctx,
fhSize = ZSTD_writeFrameHeader(dst, dstCapacity, cctx->appliedParams,
cctx->pledgedSrcSizePlusOne-1, cctx->dictID);
FORWARD_IF_ERROR(fhSize);
assert(fhSize <= dstCapacity);
dstCapacity -= fhSize;
dst = (char*)dst + fhSize;
cctx->stage = ZSTDcs_ongoing;