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complementary code comments

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on variables used / impacted during maxDist check
This commit is contained in:
Yann Collet 2019-05-28 14:12:16 -07:00
parent 4baecdf72a
commit 6453f8158f
3 changed files with 6 additions and 3 deletions
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3
lib/compress/zstd_compress.c
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@ -2866,10 +2866,13 @@ static size_t ZSTD_compress_frameChunk (ZSTD_CCtx* cctx,
ZSTD_reduceIndex(cctx, correction); ZSTD_reduceIndex(cctx, correction);
if (ms->nextToUpdate < correction) ms->nextToUpdate = 0; if (ms->nextToUpdate < correction) ms->nextToUpdate = 0;
else ms->nextToUpdate -= correction; else ms->nextToUpdate -= correction;
/* invalidate dictionaries on overflow correction */
ms->loadedDictEnd = 0; ms->loadedDictEnd = 0;
ms->dictMatchState = NULL; ms->dictMatchState = NULL;
} }
ZSTD_window_enforceMaxDist(&ms->window, ip + blockSize, maxDist, &ms->loadedDictEnd, &ms->dictMatchState); ZSTD_window_enforceMaxDist(&ms->window, ip + blockSize, maxDist, &ms->loadedDictEnd, &ms->dictMatchState);
/* Ensure hash/chain table insertion resumes no sooner than lowlimit */
if (ms->nextToUpdate < ms->window.lowLimit) ms->nextToUpdate = ms->window.lowLimit; if (ms->nextToUpdate < ms->window.lowLimit) ms->nextToUpdate = ms->window.lowLimit;
{ size_t cSize = ZSTD_compressBlock_internal(cctx, { size_t cSize = ZSTD_compressBlock_internal(cctx,

4
lib/compress/zstd_compress_internal.h
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@ -134,9 +134,9 @@ typedef struct {
typedef struct ZSTD_matchState_t ZSTD_matchState_t; typedef struct ZSTD_matchState_t ZSTD_matchState_t;
struct ZSTD_matchState_t { struct ZSTD_matchState_t {
ZSTD_window_t window; /* State for window round buffer management */ ZSTD_window_t window; /* State for window round buffer management */
U32 loadedDictEnd; /* index of end of dictionary, within dictionary's referential. Only used for attached dictionaries. Effectively same value as dictSize, since dictionary indexes start a zero */ U32 loadedDictEnd; /* index of end of dictionary, within context's referential. When dict referential is copied into active context (i.e. not attached), effectively same value as dictSize, since referential starts at zero */
U32 nextToUpdate; /* index from which to continue table update */ U32 nextToUpdate; /* index from which to continue table update */
U32 nextToUpdate3; /* index from which to continue table update */ U32 nextToUpdate3; /* index from which to continue table update of hashTable3 */
U32 hashLog3; /* dispatch table : larger == faster, more memory */ U32 hashLog3; /* dispatch table : larger == faster, more memory */
U32* hashTable; U32* hashTable;
U32* hashTable3; U32* hashTable3;

2
lib/compress/zstd_opt.c
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@ -862,7 +862,7 @@ ZSTD_compressBlock_opt_generic(ZSTD_matchState_t* ms,
DEBUGLOG(5, "ZSTD_compressBlock_opt_generic: current=%u, prefix=%u, nextToUpdate=%u", DEBUGLOG(5, "ZSTD_compressBlock_opt_generic: current=%u, prefix=%u, nextToUpdate=%u",
(U32)(ip - base), ms->window.dictLimit, ms->nextToUpdate); (U32)(ip - base), ms->window.dictLimit, ms->nextToUpdate);
assert(optLevel <= 2); assert(optLevel <= 2);
ms->nextToUpdate3 = ms->nextToUpdate; ms->nextToUpdate3 = ms->nextToUpdate; /* note : why a separate nextToUpdate3 stored into cctx->ms if it's synchtonized from nextToUpdate anyway ? */
ZSTD_rescaleFreqs(optStatePtr, (const BYTE*)src, srcSize, optLevel); ZSTD_rescaleFreqs(optStatePtr, (const BYTE*)src, srcSize, optLevel);
ip += (ip==prefixStart); ip += (ip==prefixStart);