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-rw-r--r--lib/zstd/compress/zstd_compress_internal.h375
1 files changed, 293 insertions, 82 deletions
diff --git a/lib/zstd/compress/zstd_compress_internal.h b/lib/zstd/compress/zstd_compress_internal.h
index 685d2f996cc2..71697a11ae30 100644
--- a/lib/zstd/compress/zstd_compress_internal.h
+++ b/lib/zstd/compress/zstd_compress_internal.h
@@ -57,7 +57,7 @@ typedef struct {
} ZSTD_localDict;
typedef struct {
- HUF_CElt CTable[HUF_CTABLE_SIZE_U32(255)];
+ HUF_CElt CTable[HUF_CTABLE_SIZE_ST(255)];
HUF_repeat repeatMode;
} ZSTD_hufCTables_t;
@@ -75,8 +75,55 @@ typedef struct {
ZSTD_fseCTables_t fse;
} ZSTD_entropyCTables_t;
+/* *********************************************
+* Entropy buffer statistics structs and funcs *
+***********************************************/
+/* ZSTD_hufCTablesMetadata_t :
+ * Stores Literals Block Type for a super-block in hType, and
+ * huffman tree description in hufDesBuffer.
+ * hufDesSize refers to the size of huffman tree description in bytes.
+ * This metadata is populated in ZSTD_buildBlockEntropyStats_literals() */
typedef struct {
- U32 off; /* Offset code (offset + ZSTD_REP_MOVE) for the match */
+ symbolEncodingType_e hType;
+ BYTE hufDesBuffer[ZSTD_MAX_HUF_HEADER_SIZE];
+ size_t hufDesSize;
+} ZSTD_hufCTablesMetadata_t;
+
+/* ZSTD_fseCTablesMetadata_t :
+ * Stores symbol compression modes for a super-block in {ll, ol, ml}Type, and
+ * fse tables in fseTablesBuffer.
+ * fseTablesSize refers to the size of fse tables in bytes.
+ * This metadata is populated in ZSTD_buildBlockEntropyStats_sequences() */
+typedef struct {
+ symbolEncodingType_e llType;
+ symbolEncodingType_e ofType;
+ symbolEncodingType_e mlType;
+ BYTE fseTablesBuffer[ZSTD_MAX_FSE_HEADERS_SIZE];
+ size_t fseTablesSize;
+ size_t lastCountSize; /* This is to account for bug in 1.3.4. More detail in ZSTD_entropyCompressSeqStore_internal() */
+} ZSTD_fseCTablesMetadata_t;
+
+typedef struct {
+ ZSTD_hufCTablesMetadata_t hufMetadata;
+ ZSTD_fseCTablesMetadata_t fseMetadata;
+} ZSTD_entropyCTablesMetadata_t;
+
+/* ZSTD_buildBlockEntropyStats() :
+ * Builds entropy for the block.
+ * @return : 0 on success or error code */
+size_t ZSTD_buildBlockEntropyStats(seqStore_t* seqStorePtr,
+ const ZSTD_entropyCTables_t* prevEntropy,
+ ZSTD_entropyCTables_t* nextEntropy,
+ const ZSTD_CCtx_params* cctxParams,
+ ZSTD_entropyCTablesMetadata_t* entropyMetadata,
+ void* workspace, size_t wkspSize);
+
+/* *******************************
+* Compression internals structs *
+*********************************/
+
+typedef struct {
+ U32 off; /* Offset sumtype code for the match, using ZSTD_storeSeq() format */
U32 len; /* Raw length of match */
} ZSTD_match_t;
@@ -126,7 +173,7 @@ typedef struct {
U32 offCodeSumBasePrice; /* to compare to log2(offreq) */
ZSTD_OptPrice_e priceType; /* prices can be determined dynamically, or follow a pre-defined cost structure */
const ZSTD_entropyCTables_t* symbolCosts; /* pre-calculated dictionary statistics */
- ZSTD_literalCompressionMode_e literalCompressionMode;
+ ZSTD_paramSwitch_e literalCompressionMode;
} optState_t;
typedef struct {
@@ -135,14 +182,23 @@ typedef struct {
} ZSTD_compressedBlockState_t;
typedef struct {
- BYTE const* nextSrc; /* next block here to continue on current prefix */
- BYTE const* base; /* All regular indexes relative to this position */
- BYTE const* dictBase; /* extDict indexes relative to this position */
- U32 dictLimit; /* below that point, need extDict */
- U32 lowLimit; /* below that point, no more valid data */
+ BYTE const* nextSrc; /* next block here to continue on current prefix */
+ BYTE const* base; /* All regular indexes relative to this position */
+ BYTE const* dictBase; /* extDict indexes relative to this position */
+ U32 dictLimit; /* below that point, need extDict */
+ U32 lowLimit; /* below that point, no more valid data */
+ U32 nbOverflowCorrections; /* Number of times overflow correction has run since
+ * ZSTD_window_init(). Useful for debugging coredumps
+ * and for ZSTD_WINDOW_OVERFLOW_CORRECT_FREQUENTLY.
+ */
} ZSTD_window_t;
+#define ZSTD_WINDOW_START_INDEX 2
+
typedef struct ZSTD_matchState_t ZSTD_matchState_t;
+
+#define ZSTD_ROW_HASH_CACHE_SIZE 8 /* Size of prefetching hash cache for row-based matchfinder */
+
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.
@@ -154,9 +210,17 @@ struct ZSTD_matchState_t {
*/
U32 nextToUpdate; /* index from which to continue table update */
U32 hashLog3; /* dispatch table for matches of len==3 : larger == faster, more memory */
+
+ U32 rowHashLog; /* For row-based matchfinder: Hashlog based on nb of rows in the hashTable.*/
+ U16* tagTable; /* For row-based matchFinder: A row-based table containing the hashes and head index. */
+ U32 hashCache[ZSTD_ROW_HASH_CACHE_SIZE]; /* For row-based matchFinder: a cache of hashes to improve speed */
+
U32* hashTable;
U32* hashTable3;
U32* chainTable;
+
+ U32 forceNonContiguous; /* Non-zero if we should force non-contiguous load for the next window update. */
+
int dedicatedDictSearch; /* Indicates whether this matchState is using the
* dedicated dictionary search structure.
*/
@@ -196,7 +260,7 @@ typedef struct {
} ldmState_t;
typedef struct {
- U32 enableLdm; /* 1 if enable long distance matching */
+ ZSTD_paramSwitch_e enableLdm; /* ZSTD_ps_enable to enable LDM. ZSTD_ps_auto by default */
U32 hashLog; /* Log size of hashTable */
U32 bucketSizeLog; /* Log bucket size for collision resolution, at most 8 */
U32 minMatchLength; /* Minimum match length */
@@ -227,7 +291,7 @@ struct ZSTD_CCtx_params_s {
* There is no guarantee that hint is close to actual source size */
ZSTD_dictAttachPref_e attachDictPref;
- ZSTD_literalCompressionMode_e literalCompressionMode;
+ ZSTD_paramSwitch_e literalCompressionMode;
/* Multithreading: used to pass parameters to mtctx */
int nbWorkers;
@@ -249,6 +313,15 @@ struct ZSTD_CCtx_params_s {
ZSTD_sequenceFormat_e blockDelimiters;
int validateSequences;
+ /* Block splitting */
+ ZSTD_paramSwitch_e useBlockSplitter;
+
+ /* Param for deciding whether to use row-based matchfinder */
+ ZSTD_paramSwitch_e useRowMatchFinder;
+
+ /* Always load a dictionary in ext-dict mode (not prefix mode)? */
+ int deterministicRefPrefix;
+
/* Internal use, for createCCtxParams() and freeCCtxParams() only */
ZSTD_customMem customMem;
}; /* typedef'd to ZSTD_CCtx_params within "zstd.h" */
@@ -266,12 +339,29 @@ typedef enum {
ZSTDb_buffered
} ZSTD_buffered_policy_e;
+/*
+ * Struct that contains all elements of block splitter that should be allocated
+ * in a wksp.
+ */
+#define ZSTD_MAX_NB_BLOCK_SPLITS 196
+typedef struct {
+ seqStore_t fullSeqStoreChunk;
+ seqStore_t firstHalfSeqStore;
+ seqStore_t secondHalfSeqStore;
+ seqStore_t currSeqStore;
+ seqStore_t nextSeqStore;
+
+ U32 partitions[ZSTD_MAX_NB_BLOCK_SPLITS];
+ ZSTD_entropyCTablesMetadata_t entropyMetadata;
+} ZSTD_blockSplitCtx;
+
struct ZSTD_CCtx_s {
ZSTD_compressionStage_e stage;
int cParamsChanged; /* == 1 if cParams(except wlog) or compression level are changed in requestedParams. Triggers transmission of new params to ZSTDMT (if available) then reset to 0. */
int bmi2; /* == 1 if the CPU supports BMI2 and 0 otherwise. CPU support is determined dynamically once per context lifetime. */
ZSTD_CCtx_params requestedParams;
ZSTD_CCtx_params appliedParams;
+ ZSTD_CCtx_params simpleApiParams; /* Param storage used by the simple API - not sticky. Must only be used in top-level simple API functions for storage. */
U32 dictID;
size_t dictContentSize;
@@ -296,7 +386,7 @@ struct ZSTD_CCtx_s {
ZSTD_blockState_t blockState;
U32* entropyWorkspace; /* entropy workspace of ENTROPY_WORKSPACE_SIZE bytes */
- /* Wether we are streaming or not */
+ /* Whether we are streaming or not */
ZSTD_buffered_policy_e bufferedPolicy;
/* streaming */
@@ -324,6 +414,9 @@ struct ZSTD_CCtx_s {
/* Multi-threading */
/* Tracing */
+
+ /* Workspace for block splitter */
+ ZSTD_blockSplitCtx blockSplitCtx;
};
typedef enum { ZSTD_dtlm_fast, ZSTD_dtlm_full } ZSTD_dictTableLoadMethod_e;
@@ -358,7 +451,7 @@ typedef enum {
typedef size_t (*ZSTD_blockCompressor) (
ZSTD_matchState_t* bs, seqStore_t* seqStore, U32 rep[ZSTD_REP_NUM],
void const* src, size_t srcSize);
-ZSTD_blockCompressor ZSTD_selectBlockCompressor(ZSTD_strategy strat, ZSTD_dictMode_e dictMode);
+ZSTD_blockCompressor ZSTD_selectBlockCompressor(ZSTD_strategy strat, ZSTD_paramSwitch_e rowMatchfinderMode, ZSTD_dictMode_e dictMode);
MEM_STATIC U32 ZSTD_LLcode(U32 litLength)
@@ -392,31 +485,6 @@ MEM_STATIC U32 ZSTD_MLcode(U32 mlBase)
return (mlBase > 127) ? ZSTD_highbit32(mlBase) + ML_deltaCode : ML_Code[mlBase];
}
-typedef struct repcodes_s {
- U32 rep[3];
-} repcodes_t;
-
-MEM_STATIC repcodes_t ZSTD_updateRep(U32 const rep[3], U32 const offset, U32 const ll0)
-{
- repcodes_t newReps;
- if (offset >= ZSTD_REP_NUM) { /* full offset */
- newReps.rep[2] = rep[1];
- newReps.rep[1] = rep[0];
- newReps.rep[0] = offset - ZSTD_REP_MOVE;
- } else { /* repcode */
- U32 const repCode = offset + ll0;
- if (repCode > 0) { /* note : if repCode==0, no change */
- U32 const currentOffset = (repCode==ZSTD_REP_NUM) ? (rep[0] - 1) : rep[repCode];
- newReps.rep[2] = (repCode >= 2) ? rep[1] : rep[2];
- newReps.rep[1] = rep[0];
- newReps.rep[0] = currentOffset;
- } else { /* repCode == 0 */
- ZSTD_memcpy(&newReps, rep, sizeof(newReps));
- }
- }
- return newReps;
-}
-
/* ZSTD_cParam_withinBounds:
* @return 1 if value is within cParam bounds,
* 0 otherwise */
@@ -465,17 +533,17 @@ MEM_STATIC size_t ZSTD_minGain(size_t srcSize, ZSTD_strategy strat)
return (srcSize >> minlog) + 2;
}
-MEM_STATIC int ZSTD_disableLiteralsCompression(const ZSTD_CCtx_params* cctxParams)
+MEM_STATIC int ZSTD_literalsCompressionIsDisabled(const ZSTD_CCtx_params* cctxParams)
{
switch (cctxParams->literalCompressionMode) {
- case ZSTD_lcm_huffman:
+ case ZSTD_ps_enable:
return 0;
- case ZSTD_lcm_uncompressed:
+ case ZSTD_ps_disable:
return 1;
default:
assert(0 /* impossible: pre-validated */);
ZSTD_FALLTHROUGH;
- case ZSTD_lcm_auto:
+ case ZSTD_ps_auto:
return (cctxParams->cParams.strategy == ZSTD_fast) && (cctxParams->cParams.targetLength > 0);
}
}
@@ -485,7 +553,9 @@ MEM_STATIC int ZSTD_disableLiteralsCompression(const ZSTD_CCtx_params* cctxParam
* Only called when the sequence ends past ilimit_w, so it only needs to be optimized for single
* large copies.
*/
-static void ZSTD_safecopyLiterals(BYTE* op, BYTE const* ip, BYTE const* const iend, BYTE const* ilimit_w) {
+static void
+ZSTD_safecopyLiterals(BYTE* op, BYTE const* ip, BYTE const* const iend, BYTE const* ilimit_w)
+{
assert(iend > ilimit_w);
if (ip <= ilimit_w) {
ZSTD_wildcopy(op, ip, ilimit_w - ip, ZSTD_no_overlap);
@@ -495,14 +565,30 @@ static void ZSTD_safecopyLiterals(BYTE* op, BYTE const* ip, BYTE const* const ie
while (ip < iend) *op++ = *ip++;
}
+#define ZSTD_REP_MOVE (ZSTD_REP_NUM-1)
+#define STORE_REPCODE_1 STORE_REPCODE(1)
+#define STORE_REPCODE_2 STORE_REPCODE(2)
+#define STORE_REPCODE_3 STORE_REPCODE(3)
+#define STORE_REPCODE(r) (assert((r)>=1), assert((r)<=3), (r)-1)
+#define STORE_OFFSET(o) (assert((o)>0), o + ZSTD_REP_MOVE)
+#define STORED_IS_OFFSET(o) ((o) > ZSTD_REP_MOVE)
+#define STORED_IS_REPCODE(o) ((o) <= ZSTD_REP_MOVE)
+#define STORED_OFFSET(o) (assert(STORED_IS_OFFSET(o)), (o)-ZSTD_REP_MOVE)
+#define STORED_REPCODE(o) (assert(STORED_IS_REPCODE(o)), (o)+1) /* returns ID 1,2,3 */
+#define STORED_TO_OFFBASE(o) ((o)+1)
+#define OFFBASE_TO_STORED(o) ((o)-1)
+
/*! ZSTD_storeSeq() :
- * Store a sequence (litlen, litPtr, offCode and mlBase) into seqStore_t.
- * `offCode` : distance to match + ZSTD_REP_MOVE (values <= ZSTD_REP_MOVE are repCodes).
- * `mlBase` : matchLength - MINMATCH
+ * Store a sequence (litlen, litPtr, offCode and matchLength) into seqStore_t.
+ * @offBase_minus1 : Users should use employ macros STORE_REPCODE_X and STORE_OFFSET().
+ * @matchLength : must be >= MINMATCH
* Allowed to overread literals up to litLimit.
*/
-HINT_INLINE UNUSED_ATTR
-void ZSTD_storeSeq(seqStore_t* seqStorePtr, size_t litLength, const BYTE* literals, const BYTE* litLimit, U32 offCode, size_t mlBase)
+HINT_INLINE UNUSED_ATTR void
+ZSTD_storeSeq(seqStore_t* seqStorePtr,
+ size_t litLength, const BYTE* literals, const BYTE* litLimit,
+ U32 offBase_minus1,
+ size_t matchLength)
{
BYTE const* const litLimit_w = litLimit - WILDCOPY_OVERLENGTH;
BYTE const* const litEnd = literals + litLength;
@@ -511,7 +597,7 @@ void ZSTD_storeSeq(seqStore_t* seqStorePtr, size_t litLength, const BYTE* litera
if (g_start==NULL) g_start = (const BYTE*)literals; /* note : index only works for compression within a single segment */
{ U32 const pos = (U32)((const BYTE*)literals - g_start);
DEBUGLOG(6, "Cpos%7u :%3u literals, match%4u bytes at offCode%7u",
- pos, (U32)litLength, (U32)mlBase+MINMATCH, (U32)offCode);
+ pos, (U32)litLength, (U32)matchLength, (U32)offBase_minus1);
}
#endif
assert((size_t)(seqStorePtr->sequences - seqStorePtr->sequencesStart) < seqStorePtr->maxNbSeq);
@@ -535,26 +621,66 @@ void ZSTD_storeSeq(seqStore_t* seqStorePtr, size_t litLength, const BYTE* litera
/* literal Length */
if (litLength>0xFFFF) {
- assert(seqStorePtr->longLengthID == 0); /* there can only be a single long length */
- seqStorePtr->longLengthID = 1;
+ assert(seqStorePtr->longLengthType == ZSTD_llt_none); /* there can only be a single long length */
+ seqStorePtr->longLengthType = ZSTD_llt_literalLength;
seqStorePtr->longLengthPos = (U32)(seqStorePtr->sequences - seqStorePtr->sequencesStart);
}
seqStorePtr->sequences[0].litLength = (U16)litLength;
/* match offset */
- seqStorePtr->sequences[0].offset = offCode + 1;
+ seqStorePtr->sequences[0].offBase = STORED_TO_OFFBASE(offBase_minus1);
/* match Length */
- if (mlBase>0xFFFF) {
- assert(seqStorePtr->longLengthID == 0); /* there can only be a single long length */
- seqStorePtr->longLengthID = 2;
- seqStorePtr->longLengthPos = (U32)(seqStorePtr->sequences - seqStorePtr->sequencesStart);
+ assert(matchLength >= MINMATCH);
+ { size_t const mlBase = matchLength - MINMATCH;
+ if (mlBase>0xFFFF) {
+ assert(seqStorePtr->longLengthType == ZSTD_llt_none); /* there can only be a single long length */
+ seqStorePtr->longLengthType = ZSTD_llt_matchLength;
+ seqStorePtr->longLengthPos = (U32)(seqStorePtr->sequences - seqStorePtr->sequencesStart);
+ }
+ seqStorePtr->sequences[0].mlBase = (U16)mlBase;
}
- seqStorePtr->sequences[0].matchLength = (U16)mlBase;
seqStorePtr->sequences++;
}
+/* ZSTD_updateRep() :
+ * updates in-place @rep (array of repeat offsets)
+ * @offBase_minus1 : sum-type, with same numeric representation as ZSTD_storeSeq()
+ */
+MEM_STATIC void
+ZSTD_updateRep(U32 rep[ZSTD_REP_NUM], U32 const offBase_minus1, U32 const ll0)
+{
+ if (STORED_IS_OFFSET(offBase_minus1)) { /* full offset */
+ rep[2] = rep[1];
+ rep[1] = rep[0];
+ rep[0] = STORED_OFFSET(offBase_minus1);
+ } else { /* repcode */
+ U32 const repCode = STORED_REPCODE(offBase_minus1) - 1 + ll0;
+ if (repCode > 0) { /* note : if repCode==0, no change */
+ U32 const currentOffset = (repCode==ZSTD_REP_NUM) ? (rep[0] - 1) : rep[repCode];
+ rep[2] = (repCode >= 2) ? rep[1] : rep[2];
+ rep[1] = rep[0];
+ rep[0] = currentOffset;
+ } else { /* repCode == 0 */
+ /* nothing to do */
+ }
+ }
+}
+
+typedef struct repcodes_s {
+ U32 rep[3];
+} repcodes_t;
+
+MEM_STATIC repcodes_t
+ZSTD_newRep(U32 const rep[ZSTD_REP_NUM], U32 const offBase_minus1, U32 const ll0)
+{
+ repcodes_t newReps;
+ ZSTD_memcpy(&newReps, rep, sizeof(newReps));
+ ZSTD_updateRep(newReps.rep, offBase_minus1, ll0);
+ return newReps;
+}
+
/*-*************************************
* Match length counter
@@ -778,6 +904,13 @@ MEM_STATIC void ZSTD_window_clear(ZSTD_window_t* window)
window->dictLimit = end;
}
+MEM_STATIC U32 ZSTD_window_isEmpty(ZSTD_window_t const window)
+{
+ return window.dictLimit == ZSTD_WINDOW_START_INDEX &&
+ window.lowLimit == ZSTD_WINDOW_START_INDEX &&
+ (window.nextSrc - window.base) == ZSTD_WINDOW_START_INDEX;
+}
+
/*
* ZSTD_window_hasExtDict():
* Returns non-zero if the window has a non-empty extDict.
@@ -801,15 +934,71 @@ MEM_STATIC ZSTD_dictMode_e ZSTD_matchState_dictMode(const ZSTD_matchState_t *ms)
ZSTD_noDict;
}
+/* Defining this macro to non-zero tells zstd to run the overflow correction
+ * code much more frequently. This is very inefficient, and should only be
+ * used for tests and fuzzers.
+ */
+#ifndef ZSTD_WINDOW_OVERFLOW_CORRECT_FREQUENTLY
+# ifdef FUZZING_BUILD_MODE_UNSAFE_FOR_PRODUCTION
+# define ZSTD_WINDOW_OVERFLOW_CORRECT_FREQUENTLY 1
+# else
+# define ZSTD_WINDOW_OVERFLOW_CORRECT_FREQUENTLY 0
+# endif
+#endif
+
+/*
+ * ZSTD_window_canOverflowCorrect():
+ * Returns non-zero if the indices are large enough for overflow correction
+ * to work correctly without impacting compression ratio.
+ */
+MEM_STATIC U32 ZSTD_window_canOverflowCorrect(ZSTD_window_t const window,
+ U32 cycleLog,
+ U32 maxDist,
+ U32 loadedDictEnd,
+ void const* src)
+{
+ U32 const cycleSize = 1u << cycleLog;
+ U32 const curr = (U32)((BYTE const*)src - window.base);
+ U32 const minIndexToOverflowCorrect = cycleSize
+ + MAX(maxDist, cycleSize)
+ + ZSTD_WINDOW_START_INDEX;
+
+ /* Adjust the min index to backoff the overflow correction frequency,
+ * so we don't waste too much CPU in overflow correction. If this
+ * computation overflows we don't really care, we just need to make
+ * sure it is at least minIndexToOverflowCorrect.
+ */
+ U32 const adjustment = window.nbOverflowCorrections + 1;
+ U32 const adjustedIndex = MAX(minIndexToOverflowCorrect * adjustment,
+ minIndexToOverflowCorrect);
+ U32 const indexLargeEnough = curr > adjustedIndex;
+
+ /* Only overflow correct early if the dictionary is invalidated already,
+ * so we don't hurt compression ratio.
+ */
+ U32 const dictionaryInvalidated = curr > maxDist + loadedDictEnd;
+
+ return indexLargeEnough && dictionaryInvalidated;
+}
+
/*
* ZSTD_window_needOverflowCorrection():
* Returns non-zero if the indices are getting too large and need overflow
* protection.
*/
MEM_STATIC U32 ZSTD_window_needOverflowCorrection(ZSTD_window_t const window,
+ U32 cycleLog,
+ U32 maxDist,
+ U32 loadedDictEnd,
+ void const* src,
void const* srcEnd)
{
U32 const curr = (U32)((BYTE const*)srcEnd - window.base);
+ if (ZSTD_WINDOW_OVERFLOW_CORRECT_FREQUENTLY) {
+ if (ZSTD_window_canOverflowCorrect(window, cycleLog, maxDist, loadedDictEnd, src)) {
+ return 1;
+ }
+ }
return curr > ZSTD_CURRENT_MAX;
}
@@ -821,7 +1010,6 @@ MEM_STATIC U32 ZSTD_window_needOverflowCorrection(ZSTD_window_t const window,
*
* The least significant cycleLog bits of the indices must remain the same,
* which may be 0. Every index up to maxDist in the past must be valid.
- * NOTE: (maxDist & cycleMask) must be zero.
*/
MEM_STATIC U32 ZSTD_window_correctOverflow(ZSTD_window_t* window, U32 cycleLog,
U32 maxDist, void const* src)
@@ -845,32 +1033,52 @@ MEM_STATIC U32 ZSTD_window_correctOverflow(ZSTD_window_t* window, U32 cycleLog,
* 3. (cctx->lowLimit + 1<<windowLog) < 1<<32:
* windowLog <= 31 ==> 3<<29 + 1<<windowLog < 7<<29 < 1<<32.
*/
- U32 const cycleMask = (1U << cycleLog) - 1;
+ U32 const cycleSize = 1u << cycleLog;
+ U32 const cycleMask = cycleSize - 1;
U32 const curr = (U32)((BYTE const*)src - window->base);
- U32 const currentCycle0 = curr & cycleMask;
- /* Exclude zero so that newCurrent - maxDist >= 1. */
- U32 const currentCycle1 = currentCycle0 == 0 ? (1U << cycleLog) : currentCycle0;
- U32 const newCurrent = currentCycle1 + maxDist;
+ U32 const currentCycle = curr & cycleMask;
+ /* Ensure newCurrent - maxDist >= ZSTD_WINDOW_START_INDEX. */
+ U32 const currentCycleCorrection = currentCycle < ZSTD_WINDOW_START_INDEX
+ ? MAX(cycleSize, ZSTD_WINDOW_START_INDEX)
+ : 0;
+ U32 const newCurrent = currentCycle
+ + currentCycleCorrection
+ + MAX(maxDist, cycleSize);
U32 const correction = curr - newCurrent;
- assert((maxDist & cycleMask) == 0);
+ /* maxDist must be a power of two so that:
+ * (newCurrent & cycleMask) == (curr & cycleMask)
+ * This is required to not corrupt the chains / binary tree.
+ */
+ assert((maxDist & (maxDist - 1)) == 0);
+ assert((curr & cycleMask) == (newCurrent & cycleMask));
assert(curr > newCurrent);
- /* Loose bound, should be around 1<<29 (see above) */
- assert(correction > 1<<28);
+ if (!ZSTD_WINDOW_OVERFLOW_CORRECT_FREQUENTLY) {
+ /* Loose bound, should be around 1<<29 (see above) */
+ assert(correction > 1<<28);
+ }
window->base += correction;
window->dictBase += correction;
- if (window->lowLimit <= correction) window->lowLimit = 1;
- else window->lowLimit -= correction;
- if (window->dictLimit <= correction) window->dictLimit = 1;
- else window->dictLimit -= correction;
+ if (window->lowLimit < correction + ZSTD_WINDOW_START_INDEX) {
+ window->lowLimit = ZSTD_WINDOW_START_INDEX;
+ } else {
+ window->lowLimit -= correction;
+ }
+ if (window->dictLimit < correction + ZSTD_WINDOW_START_INDEX) {
+ window->dictLimit = ZSTD_WINDOW_START_INDEX;
+ } else {
+ window->dictLimit -= correction;
+ }
/* Ensure we can still reference the full window. */
assert(newCurrent >= maxDist);
- assert(newCurrent - maxDist >= 1);
+ assert(newCurrent - maxDist >= ZSTD_WINDOW_START_INDEX);
/* Ensure that lowLimit and dictLimit didn't underflow. */
assert(window->lowLimit <= newCurrent);
assert(window->dictLimit <= newCurrent);
+ ++window->nbOverflowCorrections;
+
DEBUGLOG(4, "Correction of 0x%x bytes to lowLimit=0x%x", correction,
window->lowLimit);
return correction;
@@ -975,11 +1183,13 @@ ZSTD_checkDictValidity(const ZSTD_window_t* window,
MEM_STATIC void ZSTD_window_init(ZSTD_window_t* window) {
ZSTD_memset(window, 0, sizeof(*window));
- window->base = (BYTE const*)"";
- window->dictBase = (BYTE const*)"";
- window->dictLimit = 1; /* start from 1, so that 1st position is valid */
- window->lowLimit = 1; /* it ensures first and later CCtx usages compress the same */
- window->nextSrc = window->base + 1; /* see issue #1241 */
+ window->base = (BYTE const*)" ";
+ window->dictBase = (BYTE const*)" ";
+ ZSTD_STATIC_ASSERT(ZSTD_DUBT_UNSORTED_MARK < ZSTD_WINDOW_START_INDEX); /* Start above ZSTD_DUBT_UNSORTED_MARK */
+ window->dictLimit = ZSTD_WINDOW_START_INDEX; /* start from >0, so that 1st position is valid */
+ window->lowLimit = ZSTD_WINDOW_START_INDEX; /* it ensures first and later CCtx usages compress the same */
+ window->nextSrc = window->base + ZSTD_WINDOW_START_INDEX; /* see issue #1241 */
+ window->nbOverflowCorrections = 0;
}
/*
@@ -990,7 +1200,8 @@ MEM_STATIC void ZSTD_window_init(ZSTD_window_t* window) {
* Returns non-zero if the segment is contiguous.
*/
MEM_STATIC U32 ZSTD_window_update(ZSTD_window_t* window,
- void const* src, size_t srcSize)
+ void const* src, size_t srcSize,
+ int forceNonContiguous)
{
BYTE const* const ip = (BYTE const*)src;
U32 contiguous = 1;
@@ -1000,7 +1211,7 @@ MEM_STATIC U32 ZSTD_window_update(ZSTD_window_t* window,
assert(window->base != NULL);
assert(window->dictBase != NULL);
/* Check if blocks follow each other */
- if (src != window->nextSrc) {
+ if (src != window->nextSrc || forceNonContiguous) {
/* not contiguous */
size_t const distanceFromBase = (size_t)(window->nextSrc - window->base);
DEBUGLOG(5, "Non contiguous blocks, new segment starts at %u", window->dictLimit);
@@ -1030,15 +1241,15 @@ MEM_STATIC U32 ZSTD_window_update(ZSTD_window_t* window,
*/
MEM_STATIC U32 ZSTD_getLowestMatchIndex(const ZSTD_matchState_t* ms, U32 curr, unsigned windowLog)
{
- U32 const maxDistance = 1U << windowLog;
- U32 const lowestValid = ms->window.lowLimit;
- U32 const withinWindow = (curr - lowestValid > maxDistance) ? curr - maxDistance : lowestValid;
- U32 const isDictionary = (ms->loadedDictEnd != 0);
+ U32 const maxDistance = 1U << windowLog;
+ U32 const lowestValid = ms->window.lowLimit;
+ U32 const withinWindow = (curr - lowestValid > maxDistance) ? curr - maxDistance : lowestValid;
+ U32 const isDictionary = (ms->loadedDictEnd != 0);
/* When using a dictionary the entire dictionary is valid if a single byte of the dictionary
* is within the window. We invalidate the dictionary (and set loadedDictEnd to 0) when it isn't
* valid for the entire block. So this check is sufficient to find the lowest valid match index.
*/
- U32 const matchLowest = isDictionary ? lowestValid : withinWindow;
+ U32 const matchLowest = isDictionary ? lowestValid : withinWindow;
return matchLowest;
}
generated by cgit v1.2.3 (git 2.39.1) at 2025-01-18 20:11:23 +0100