diff options
Diffstat (limited to 'thirdparty/zstd/compress/zstd_compress_internal.h')
| -rw-r--r-- | thirdparty/zstd/compress/zstd_compress_internal.h | 84 |
1 files changed, 69 insertions, 15 deletions
diff --git a/thirdparty/zstd/compress/zstd_compress_internal.h b/thirdparty/zstd/compress/zstd_compress_internal.h index 5495899be3..6d623cc6be 100644 --- a/thirdparty/zstd/compress/zstd_compress_internal.h +++ b/thirdparty/zstd/compress/zstd_compress_internal.h @@ -134,9 +134,15 @@ typedef struct { typedef struct ZSTD_matchState_t ZSTD_matchState_t; struct ZSTD_matchState_t { ZSTD_window_t window; /* State for window round buffer management */ - 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 from zero */ + U32 loadedDictEnd; /* index of end of dictionary, within context's referential. + * When loadedDictEnd != 0, a dictionary is in use, and still valid. + * This relies on a mechanism to set loadedDictEnd=0 when dictionary is no longer within distance. + * Such mechanism is provided within ZSTD_window_enforceMaxDist() and ZSTD_checkDictValidity(). + * When dict referential is copied into active context (i.e. not attached), + * loadedDictEnd == dictSize, since referential starts from zero. + */ U32 nextToUpdate; /* index from which to continue table update */ - U32 hashLog3; /* dispatch table : larger == faster, more memory */ + U32 hashLog3; /* dispatch table for matches of len==3 : larger == faster, more memory */ U32* hashTable; U32* hashTable3; U32* chainTable; @@ -307,6 +313,30 @@ MEM_STATIC U32 ZSTD_MLcode(U32 mlBase) return (mlBase > 127) ? ZSTD_highbit32(mlBase) + ML_deltaCode : ML_Code[mlBase]; } +/* ZSTD_cParam_withinBounds: + * @return 1 if value is within cParam bounds, + * 0 otherwise */ +MEM_STATIC int ZSTD_cParam_withinBounds(ZSTD_cParameter cParam, int value) +{ + ZSTD_bounds const bounds = ZSTD_cParam_getBounds(cParam); + if (ZSTD_isError(bounds.error)) return 0; + if (value < bounds.lowerBound) return 0; + if (value > bounds.upperBound) return 0; + return 1; +} + +/* ZSTD_minGain() : + * minimum compression required + * to generate a compress block or a compressed literals section. + * note : use same formula for both situations */ +MEM_STATIC size_t ZSTD_minGain(size_t srcSize, ZSTD_strategy strat) +{ + U32 const minlog = (strat>=ZSTD_btultra) ? (U32)(strat) - 1 : 6; + ZSTD_STATIC_ASSERT(ZSTD_btultra == 8); + assert(ZSTD_cParam_withinBounds(ZSTD_c_strategy, strat)); + return (srcSize >> minlog) + 2; +} + /*! ZSTD_storeSeq() : * Store a sequence (literal length, literals, offset code and match length code) into seqStore_t. * `offsetCode` : distance to match + 3 (values 1-3 are repCodes). @@ -326,7 +356,7 @@ MEM_STATIC void ZSTD_storeSeq(seqStore_t* seqStorePtr, size_t litLength, const v /* copy Literals */ assert(seqStorePtr->maxNbLit <= 128 KB); assert(seqStorePtr->lit + litLength <= seqStorePtr->litStart + seqStorePtr->maxNbLit); - ZSTD_wildcopy(seqStorePtr->lit, literals, litLength, ZSTD_no_overlap); + ZSTD_wildcopy(seqStorePtr->lit, literals, (ptrdiff_t)litLength, ZSTD_no_overlap); seqStorePtr->lit += litLength; /* literal Length */ @@ -739,24 +769,37 @@ ZSTD_window_enforceMaxDist(ZSTD_window_t* window, /* Similar to ZSTD_window_enforceMaxDist(), * but only invalidates dictionary - * when input progresses beyond window size. */ + * when input progresses beyond window size. + * assumption : loadedDictEndPtr and dictMatchStatePtr are valid (non NULL) + * loadedDictEnd uses same referential as window->base + * maxDist is the window size */ MEM_STATIC void -ZSTD_checkDictValidity(ZSTD_window_t* window, +ZSTD_checkDictValidity(const ZSTD_window_t* window, const void* blockEnd, U32 maxDist, U32* loadedDictEndPtr, const ZSTD_matchState_t** dictMatchStatePtr) { - U32 const blockEndIdx = (U32)((BYTE const*)blockEnd - window->base); - U32 const loadedDictEnd = (loadedDictEndPtr != NULL) ? *loadedDictEndPtr : 0; - DEBUGLOG(5, "ZSTD_checkDictValidity: blockEndIdx=%u, maxDist=%u, loadedDictEnd=%u", - (unsigned)blockEndIdx, (unsigned)maxDist, (unsigned)loadedDictEnd); - - if (loadedDictEnd && (blockEndIdx > maxDist + loadedDictEnd)) { - /* On reaching window size, dictionaries are invalidated */ - if (loadedDictEndPtr) *loadedDictEndPtr = 0; - if (dictMatchStatePtr) *dictMatchStatePtr = NULL; - } + assert(loadedDictEndPtr != NULL); + assert(dictMatchStatePtr != NULL); + { U32 const blockEndIdx = (U32)((BYTE const*)blockEnd - window->base); + U32 const loadedDictEnd = *loadedDictEndPtr; + DEBUGLOG(5, "ZSTD_checkDictValidity: blockEndIdx=%u, maxDist=%u, loadedDictEnd=%u", + (unsigned)blockEndIdx, (unsigned)maxDist, (unsigned)loadedDictEnd); + assert(blockEndIdx >= loadedDictEnd); + + if (blockEndIdx > loadedDictEnd + maxDist) { + /* On reaching window size, dictionaries are invalidated. + * For simplification, if window size is reached anywhere within next block, + * the dictionary is invalidated for the full block. + */ + DEBUGLOG(6, "invalidating dictionary for current block (distance > windowSize)"); + *loadedDictEndPtr = 0; + *dictMatchStatePtr = NULL; + } else { + if (*loadedDictEndPtr != 0) { + DEBUGLOG(6, "dictionary considered valid for current block"); + } } } } /** @@ -798,6 +841,17 @@ MEM_STATIC U32 ZSTD_window_update(ZSTD_window_t* window, return contiguous; } +MEM_STATIC U32 ZSTD_getLowestMatchIndex(const ZSTD_matchState_t* ms, U32 current, unsigned windowLog) +{ + U32 const maxDistance = 1U << windowLog; + U32 const lowestValid = ms->window.lowLimit; + U32 const withinWindow = (current - lowestValid > maxDistance) ? current - maxDistance : lowestValid; + U32 const isDictionary = (ms->loadedDictEnd != 0); + U32 const matchLowest = isDictionary ? lowestValid : withinWindow; + return matchLowest; +} + + /* debug functions */ #if (DEBUGLEVEL>=2) |