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authorYann Collet <Cyan4973@users.noreply.github.com>2017-11-09 22:13:30 (GMT)
committerGitHub <noreply@github.com>2017-11-09 22:13:30 (GMT)
commitdac26084a902657f9b530b09c3a21e000249109b (patch)
tree39a25ffc21da8f40705677873f984d6e8428a2ef /lib
parente6365b1854eddb9772693db50b07e9057d0fe4f6 (diff)
parentdc3ed5b6a7d9cc7d251a1942558e37793d5575b8 (diff)
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Merge pull request #416 from lz4/newopt
Improve Optimal parser
Diffstat (limited to 'lib')
-rw-r--r--lib/README.md2
-rw-r--r--lib/lz4.c20
-rw-r--r--lib/lz4frame.c8
-rw-r--r--lib/lz4hc.c261
-rw-r--r--lib/lz4hc.h50
-rw-r--r--lib/lz4opt.h465
6 files changed, 415 insertions, 391 deletions
diff --git a/lib/README.md b/lib/README.md
index 7082fe3..fc5d4e9 100644
--- a/lib/README.md
+++ b/lib/README.md
@@ -15,7 +15,7 @@ They generate and decode data using [LZ4 block format].
For more compression ratio at the cost of compression speed,
the High Compression variant called **lz4hc** is available.
-Add files **`lz4hc.c`** and **`lz4hc.h`**.
+Add files **`lz4hc.c`**, **`lz4hc.h`** and **`lz4opt.h`**.
The variant still depends on regular `lib/lz4.*` source files.
diff --git a/lib/lz4.c b/lib/lz4.c
index 6157285..cc76eba 100644
--- a/lib/lz4.c
+++ b/lib/lz4.c
@@ -323,15 +323,24 @@ static const int LZ4_minLength = (MFLIMIT+1);
/*-************************************
* Error detection
**************************************/
+#if defined(LZ4_DEBUG) && (LZ4_DEBUG>=1)
+# include <assert.h>
+#else
+# ifndef assert
+# define assert(condition) ((void)0)
+# endif
+#endif
+
#define LZ4_STATIC_ASSERT(c) { enum { LZ4_static_assert = 1/(int)(!!(c)) }; } /* use only *after* variable declarations */
#if defined(LZ4_DEBUG) && (LZ4_DEBUG>=2)
# include <stdio.h>
-# define DEBUGLOG(l, ...) { \
- if (l<=LZ4_DEBUG) { \
- fprintf(stderr, __FILE__ ": "); \
- fprintf(stderr, __VA_ARGS__); \
- fprintf(stderr, " \n"); \
+static int g_debuglog_enable = 1;
+# define DEBUGLOG(l, ...) { \
+ if ((g_debuglog_enable) && (l<=LZ4_DEBUG)) { \
+ fprintf(stderr, __FILE__ ": "); \
+ fprintf(stderr, __VA_ARGS__); \
+ fprintf(stderr, " \n"); \
} }
#else
# define DEBUGLOG(l, ...) {} /* disabled */
@@ -990,6 +999,7 @@ LZ4_stream_t* LZ4_createStream(void)
void LZ4_resetStream (LZ4_stream_t* LZ4_stream)
{
+ DEBUGLOG(4, "LZ4_resetStream");
MEM_INIT(LZ4_stream, 0, sizeof(LZ4_stream_t));
}
diff --git a/lib/lz4frame.c b/lib/lz4frame.c
index 3adbdd9..ebd1089 100644
--- a/lib/lz4frame.c
+++ b/lib/lz4frame.c
@@ -322,7 +322,7 @@ size_t LZ4F_compressFrame_usingCDict(void* dstBuffer, size_t dstCapacity,
const LZ4F_preferences_t* preferencesPtr)
{
LZ4F_cctx_t cctxI;
- LZ4_stream_t lz4ctx;
+ LZ4_stream_t lz4ctx; /* pretty large on stack */
LZ4F_preferences_t prefs;
LZ4F_compressOptions_t options;
BYTE* const dstStart = (BYTE*) dstBuffer;
@@ -504,15 +504,15 @@ size_t LZ4F_compressBegin_usingCDict(LZ4F_cctx* cctxPtr,
cctxPtr->prefs = *preferencesPtr;
/* Ctx Management */
- { U32 const tableID = (cctxPtr->prefs.compressionLevel < LZ4HC_CLEVEL_MIN) ? 1 : 2; /* 0:nothing ; 1:LZ4 table ; 2:HC tables */
- if (cctxPtr->lz4CtxLevel < tableID) {
+ { U32 const ctxTypeID = (cctxPtr->prefs.compressionLevel < LZ4HC_CLEVEL_MIN) ? 1 : 2; /* 0:nothing ; 1:LZ4 table ; 2:HC tables */
+ if (cctxPtr->lz4CtxLevel < ctxTypeID) {
FREEMEM(cctxPtr->lz4CtxPtr);
if (cctxPtr->prefs.compressionLevel < LZ4HC_CLEVEL_MIN)
cctxPtr->lz4CtxPtr = (void*)LZ4_createStream();
else
cctxPtr->lz4CtxPtr = (void*)LZ4_createStreamHC();
if (cctxPtr->lz4CtxPtr == NULL) return err0r(LZ4F_ERROR_allocation_failed);
- cctxPtr->lz4CtxLevel = tableID;
+ cctxPtr->lz4CtxLevel = ctxTypeID;
} }
/* Buffer Management */
diff --git a/lib/lz4hc.c b/lib/lz4hc.c
index d7f8d23..60690a0 100644
--- a/lib/lz4hc.c
+++ b/lib/lz4hc.c
@@ -49,6 +49,7 @@
/*=== Dependency ===*/
+#define LZ4_HC_STATIC_LINKING_ONLY
#include "lz4hc.h"
@@ -116,54 +117,71 @@ LZ4_FORCE_INLINE void LZ4HC_Insert (LZ4HC_CCtx_internal* hc4, const BYTE* ip)
hc4->nextToUpdate = target;
}
-
-LZ4_FORCE_INLINE int LZ4HC_InsertAndFindBestMatch (LZ4HC_CCtx_internal* const hc4, /* Index table will be updated */
- const BYTE* const ip, const BYTE* const iLimit,
- const BYTE** matchpos,
- const int maxNbAttempts)
+/** LZ4HC_countBack() :
+ * @return : negative value, nb of common bytes before ip/match */
+LZ4_FORCE_INLINE
+int LZ4HC_countBack(const BYTE* const ip, const BYTE* const match,
+ const BYTE* const iMin, const BYTE* const mMin)
{
- U16* const chainTable = hc4->chainTable;
- U32* const HashTable = hc4->hashTable;
- const BYTE* const base = hc4->base;
- const BYTE* const dictBase = hc4->dictBase;
- const U32 dictLimit = hc4->dictLimit;
- const U32 lowLimit = (hc4->lowLimit + 64 KB > (U32)(ip-base)) ? hc4->lowLimit : (U32)(ip - base) - (64 KB - 1);
- U32 matchIndex;
- int nbAttempts = maxNbAttempts;
- size_t ml = 0;
+ int back=0;
+ while ( (ip+back > iMin)
+ && (match+back > mMin)
+ && (ip[back-1] == match[back-1]))
+ back--;
+ return back;
+}
- /* HC4 match finder */
- LZ4HC_Insert(hc4, ip);
- matchIndex = HashTable[LZ4HC_hashPtr(ip)];
+/* LZ4HC_countPattern() :
+ * pattern32 must be a sample of repetitive pattern of length 1, 2 or 4 (but not 3!) */
+static unsigned LZ4HC_countPattern(const BYTE* ip, const BYTE* const iEnd, U32 const pattern32)
+{
+ const BYTE* const iStart = ip;
+ reg_t const pattern = (sizeof(pattern)==8) ? (reg_t)pattern32 + (((reg_t)pattern32) << 32) : pattern32;
+
+ while (likely(ip < iEnd-(sizeof(pattern)-1))) {
+ reg_t const diff = LZ4_read_ARCH(ip) ^ pattern;
+ if (!diff) { ip+=sizeof(pattern); continue; }
+ ip += LZ4_NbCommonBytes(diff);
+ return (unsigned)(ip - iStart);
+ }
- while ((matchIndex>=lowLimit) && (nbAttempts)) {
- nbAttempts--;
- if (matchIndex >= dictLimit) {
- const BYTE* const match = base + matchIndex;
- if ( (*(match+ml) == *(ip+ml)) /* can be longer */
- && (LZ4_read32(match) == LZ4_read32(ip)) )
- {
- size_t const mlt = LZ4_count(ip+MINMATCH, match+MINMATCH, iLimit) + MINMATCH;
- if (mlt > ml) { ml = mlt; *matchpos = match; }
- }
- } else {
- const BYTE* const match = dictBase + matchIndex;
- if (LZ4_read32(match) == LZ4_read32(ip)) {
- size_t mlt;
- const BYTE* vLimit = ip + (dictLimit - matchIndex);
- if (vLimit > iLimit) vLimit = iLimit;
- mlt = LZ4_count(ip+MINMATCH, match+MINMATCH, vLimit) + MINMATCH;
- if ((ip+mlt == vLimit) && (vLimit < iLimit))
- mlt += LZ4_count(ip+mlt, base+dictLimit, iLimit);
- if (mlt > ml) { ml = mlt; *matchpos = base + matchIndex; } /* virtual matchpos */
- }
+ if (LZ4_isLittleEndian()) {
+ reg_t patternByte = pattern;
+ while ((ip<iEnd) && (*ip == (BYTE)patternByte)) {
+ ip++; patternByte >>= 8;
+ }
+ } else { /* big endian */
+ U32 bitOffset = (sizeof(pattern)*8) - 8;
+ while (ip < iEnd) {
+ BYTE const byte = (BYTE)(pattern >> bitOffset);
+ if (*ip != byte) break;
+ ip ++; bitOffset -= 8;
}
- matchIndex -= DELTANEXTU16(chainTable, matchIndex);
}
- return (int)ml;
+ return (unsigned)(ip - iStart);
+}
+
+/* LZ4HC_reverseCountPattern() :
+ * pattern must be a sample of repetitive pattern of length 1, 2 or 4 (but not 3!)
+ * read using natural platform endianess */
+static unsigned LZ4HC_reverseCountPattern(const BYTE* ip, const BYTE* const iLow, U32 pattern)
+{
+ const BYTE* const iStart = ip;
+
+ while (likely(ip >= iLow+4)) {
+ if (LZ4_read32(ip-4) != pattern) break;
+ ip -= 4;
+ }
+ { const BYTE* bytePtr = (const BYTE*)(&pattern) + 3; /* works for any endianess */
+ while (likely(ip>iLow)) {
+ if (ip[-1] != *bytePtr) break;
+ ip--; bytePtr--;
+ } }
+ return (unsigned)(iStart - ip);
}
+typedef enum { rep_untested, rep_not, rep_confirmed } repeat_state_e;
LZ4_FORCE_INLINE int LZ4HC_InsertAndGetWiderMatch (
LZ4HC_CCtx_internal* hc4,
@@ -180,60 +198,117 @@ LZ4_FORCE_INLINE int LZ4HC_InsertAndGetWiderMatch (
const BYTE* const base = hc4->base;
const U32 dictLimit = hc4->dictLimit;
const BYTE* const lowPrefixPtr = base + dictLimit;
- const U32 lowLimit = (hc4->lowLimit + 64 KB > (U32)(ip-base)) ? hc4->lowLimit : (U32)(ip - base) - (64 KB - 1);
+ const U32 lowLimit = (hc4->lowLimit + 64 KB > (U32)(ip-base)) ? hc4->lowLimit : (U32)(ip - base) - MAX_DISTANCE;
const BYTE* const dictBase = hc4->dictBase;
int const delta = (int)(ip-iLowLimit);
int nbAttempts = maxNbAttempts;
+ U32 const pattern = LZ4_read32(ip);
U32 matchIndex;
+ repeat_state_e repeat = rep_untested;
+ size_t srcPatternLength = 0;
-
+ DEBUGLOG(7, "LZ4HC_InsertAndGetWiderMatch");
/* First Match */
LZ4HC_Insert(hc4, ip);
matchIndex = HashTable[LZ4HC_hashPtr(ip)];
+ DEBUGLOG(7, "First match at index %u / %u (lowLimit)",
+ matchIndex, lowLimit);
while ((matchIndex>=lowLimit) && (nbAttempts)) {
+ DEBUGLOG(7, "remaining attempts : %i", nbAttempts);
nbAttempts--;
if (matchIndex >= dictLimit) {
const BYTE* const matchPtr = base + matchIndex;
if (*(iLowLimit + longest) == *(matchPtr - delta + longest)) {
- if (LZ4_read32(matchPtr) == LZ4_read32(ip)) {
+ if (LZ4_read32(matchPtr) == pattern) {
int mlt = MINMATCH + LZ4_count(ip+MINMATCH, matchPtr+MINMATCH, iHighLimit);
+ #if 0
+ /* more generic but unfortunately slower on clang */
+ int const back = LZ4HC_countBack(ip, matchPtr, iLowLimit, lowPrefixPtr);
+ #else
int back = 0;
-
while ( (ip+back > iLowLimit)
&& (matchPtr+back > lowPrefixPtr)
&& (ip[back-1] == matchPtr[back-1])) {
back--;
}
-
+ #endif
mlt -= back;
if (mlt > longest) {
longest = mlt;
*matchpos = matchPtr+back;
*startpos = ip+back;
- } } }
- } else {
+ } }
+ }
+ } else { /* matchIndex < dictLimit */
const BYTE* const matchPtr = dictBase + matchIndex;
- if (LZ4_read32(matchPtr) == LZ4_read32(ip)) {
+ if (LZ4_read32(matchPtr) == pattern) {
int mlt;
- int back=0;
+ int back = 0;
const BYTE* vLimit = ip + (dictLimit - matchIndex);
if (vLimit > iHighLimit) vLimit = iHighLimit;
mlt = LZ4_count(ip+MINMATCH, matchPtr+MINMATCH, vLimit) + MINMATCH;
if ((ip+mlt == vLimit) && (vLimit < iHighLimit))
mlt += LZ4_count(ip+mlt, base+dictLimit, iHighLimit);
- while ((ip+back > iLowLimit) && (matchIndex+back > lowLimit) && (ip[back-1] == matchPtr[back-1])) back--;
+ while ( (ip+back > iLowLimit)
+ && (matchIndex+back > lowLimit)
+ && (ip[back-1] == matchPtr[back-1]))
+ back--;
mlt -= back;
- if (mlt > longest) { longest = mlt; *matchpos = base + matchIndex + back; *startpos = ip+back; }
- }
- }
- matchIndex -= DELTANEXTU16(chainTable, matchIndex);
- }
+ if (mlt > longest) {
+ longest = mlt;
+ *matchpos = base + matchIndex + back;
+ *startpos = ip + back;
+ } } }
+
+ { U32 const nextOffset = DELTANEXTU16(chainTable, matchIndex);
+ matchIndex -= nextOffset;
+ if (nextOffset==1) {
+ /* may be a repeated pattern */
+ if (repeat == rep_untested) {
+ if ( ((pattern & 0xFFFF) == (pattern >> 16))
+ & ((pattern & 0xFF) == (pattern >> 24)) ) {
+ repeat = rep_confirmed;
+ srcPatternLength = LZ4HC_countPattern(ip+4, iHighLimit, pattern) + 4;
+ } else {
+ repeat = rep_not;
+ } }
+ if ( (repeat == rep_confirmed)
+ && (matchIndex >= dictLimit) ) { /* same segment only */
+ const BYTE* const matchPtr = base + matchIndex;
+ if (LZ4_read32(matchPtr) == pattern) { /* good candidate */
+ size_t const forwardPatternLength = LZ4HC_countPattern(matchPtr+sizeof(pattern), iHighLimit, pattern) + sizeof(pattern);
+ const BYTE* const maxLowPtr = (lowPrefixPtr + MAX_DISTANCE >= ip) ? lowPrefixPtr : ip - MAX_DISTANCE;
+ size_t const backLength = LZ4HC_reverseCountPattern(matchPtr, maxLowPtr, pattern);
+ size_t const currentSegmentLength = backLength + forwardPatternLength;
+
+ if ( (currentSegmentLength >= srcPatternLength) /* current pattern segment large enough to contain full srcPatternLength */
+ && (forwardPatternLength <= srcPatternLength) ) { /* haven't reached this position yet */
+ matchIndex += (U32)forwardPatternLength - (U32)srcPatternLength; /* best position, full pattern, might be followed by more match */
+ } else {
+ matchIndex -= (U32)backLength; /* let's go to farthest segment position, will find a match of length currentSegmentLength + maybe some back */
+ }
+ } } } }
+ } /* while ((matchIndex>=lowLimit) && (nbAttempts)) */
return longest;
}
+LZ4_FORCE_INLINE
+int LZ4HC_InsertAndFindBestMatch(LZ4HC_CCtx_internal* const hc4, /* Index table will be updated */
+ const BYTE* const ip, const BYTE* const iLimit,
+ const BYTE** matchpos,
+ const int maxNbAttempts)
+{
+ const BYTE* uselessPtr = ip;
+ /* note : LZ4HC_InsertAndGetWiderMatch() is able to modify the starting position of a match (*startpos),
+ * but this won't be the case here, as we define iLowLimit==ip,
+ * so LZ4HC_InsertAndGetWiderMatch() won't be allowed to search past ip */
+ return LZ4HC_InsertAndGetWiderMatch(hc4, ip, ip, iLimit, MINMATCH-1, matchpos, &uselessPtr, maxNbAttempts);
+}
+
+
typedef enum {
noLimit = 0,
@@ -241,10 +316,6 @@ typedef enum {
limitedDestSize = 2,
} limitedOutput_directive;
-#ifndef LZ4HC_DEBUG
-# define LZ4HC_DEBUG 0
-#endif
-
/* LZ4HC_encodeSequence() :
* @return : 0 if ok,
* 1 if buffer issue detected */
@@ -260,9 +331,21 @@ LZ4_FORCE_INLINE int LZ4HC_encodeSequence (
size_t length;
BYTE* const token = (*op)++;
-#if LZ4HC_DEBUG
- printf("literal : %u -- match : %u -- offset : %u\n",
- (U32)(*ip - *anchor), (U32)matchLength, (U32)(*ip-match));
+#if defined(LZ4_DEBUG) && (LZ4_DEBUG >= 2)
+ static const BYTE* start = NULL;
+ static U32 totalCost = 0;
+ U32 const pos = (start==NULL) ? 0 : (U32)(*anchor - start);
+ U32 const ll = (U32)(*ip - *anchor);
+ U32 const llAdd = (ll>=15) ? ((ll-15) / 255) + 1 : 0;
+ U32 const mlAdd = (matchLength>=19) ? ((matchLength-19) / 255) + 1 : 0;
+ U32 const cost = 1 + llAdd + ll + 2 + mlAdd;
+ if (start==NULL) start = *anchor; /* only works for single segment */
+ //g_debuglog_enable = (pos >= 2228) & (pos <= 2262);
+ DEBUGLOG(2, "pos:%7u -- literals:%3u, match:%4i, offset:%5u, cost:%3u + %u",
+ pos,
+ (U32)(*ip - *anchor), matchLength, (U32)(*ip-match),
+ cost, totalCost);
+ totalCost += cost;
#endif
/* Encode Literal length */
@@ -285,6 +368,7 @@ LZ4_FORCE_INLINE int LZ4HC_encodeSequence (
LZ4_writeLE16(*op, (U16)(*ip-match)); *op += 2;
/* Encode MatchLength */
+ assert(matchLength >= MINMATCH);
length = (size_t)(matchLength - MINMATCH);
if ((limit) && (*op + (length >> 8) + (1 + LASTLITERALS) > oend)) return 1; /* Check output limit */
if (length >= ML_MASK) {
@@ -344,16 +428,13 @@ static int LZ4HC_compress_hashChain (
if (limit == limitedDestSize && maxOutputSize < 1) return 0; /* Impossible to store anything */
if ((U32)inputSize > (U32)LZ4_MAX_INPUT_SIZE) return 0; /* Unsupported input size, too large (or negative) */
- ctx->end += inputSize;
if (limit == limitedDestSize) oend -= LASTLITERALS; /* Hack for support limitations LZ4 decompressor */
if (inputSize < LZ4_minLength) goto _last_literals; /* Input too small, no compression (all literals) */
- ip++;
-
/* Main Loop */
while (ip < mflimit) {
- ml = LZ4HC_InsertAndFindBestMatch (ctx, ip, matchlimit, (&ref), maxNbAttempts);
- if (!ml) { ip++; continue; }
+ ml = LZ4HC_InsertAndFindBestMatch (ctx, ip, matchlimit, &ref, maxNbAttempts);
+ if (ml<MINMATCH) { ip++; continue; }
/* saved, in case we would skip too much */
start0 = ip;
@@ -527,14 +608,6 @@ _dest_overflow:
return 0;
}
-static int LZ4HC_getSearchNum(int compressionLevel)
-{
- switch (compressionLevel) {
- default: return 0; /* unused */
- case 11: return 128;
- case 12: return 1<<10;
- }
-}
static int LZ4HC_compress_generic (
LZ4HC_CCtx_internal* const ctx,
@@ -546,21 +619,19 @@ static int LZ4HC_compress_generic (
limitedOutput_directive limit
)
{
- if (cLevel < 1) cLevel = LZ4HC_CLEVEL_DEFAULT; /* note : convention is different from lz4frame, maybe to reconsider */
+ ctx->end += *srcSizePtr;
+ if (cLevel < 1) cLevel = LZ4HC_CLEVEL_DEFAULT; /* note : convention is different from lz4frame, maybe something to review */
if (cLevel > 9) {
if (limit == limitedDestSize) cLevel = 10;
switch (cLevel) {
case 10:
- return LZ4HC_compress_hashChain(ctx, src, dst, srcSizePtr, dstCapacity, 1 << 12, limit);
+ return LZ4HC_compress_hashChain(ctx, src, dst, srcSizePtr, dstCapacity, 1<<12, limit);
case 11:
- ctx->searchNum = LZ4HC_getSearchNum(cLevel);
- return LZ4HC_compress_optimal(ctx, src, dst, *srcSizePtr, dstCapacity, limit, 128, 0);
+ return LZ4HC_compress_optimal(ctx, src, dst, *srcSizePtr, dstCapacity, limit, 512, 128, 0);
default:
- cLevel = 12;
/* fall-through */
case 12:
- ctx->searchNum = LZ4HC_getSearchNum(cLevel);
- return LZ4HC_compress_optimal(ctx, src, dst, *srcSizePtr, dstCapacity, limit, LZ4_OPT_NUM, 1);
+ return LZ4HC_compress_optimal(ctx, src, dst, *srcSizePtr, dstCapacity, limit, 1<<13, LZ4_OPT_NUM, 1);
}
}
return LZ4HC_compress_hashChain(ctx, src, dst, srcSizePtr, dstCapacity, 1 << (cLevel-1), limit); /* levels 1-9 */
@@ -596,8 +667,7 @@ int LZ4_compress_HC(const char* src, char* dst, int srcSize, int dstCapacity, in
}
/* LZ4_compress_HC_destSize() :
- * currently, only compatible with Hash Chain implementation,
- * hence limit compression level to LZ4HC_CLEVEL_OPT_MIN-1*/
+ * only compatible with Hash Chain match finder */
int LZ4_compress_HC_destSize(void* LZ4HC_Data, const char* source, char* dest, int* sourceSizePtr, int targetDestSize, int cLevel)
{
LZ4HC_CCtx_internal* const ctx = &((LZ4_streamHC_t*)LZ4HC_Data)->internal_donotuse;
@@ -624,18 +694,13 @@ void LZ4_resetStreamHC (LZ4_streamHC_t* LZ4_streamHCPtr, int compressionLevel)
{
LZ4_STATIC_ASSERT(sizeof(LZ4HC_CCtx_internal) <= sizeof(size_t) * LZ4_STREAMHCSIZE_SIZET); /* if compilation fails here, LZ4_STREAMHCSIZE must be increased */
LZ4_streamHCPtr->internal_donotuse.base = NULL;
- if (compressionLevel > LZ4HC_CLEVEL_MAX) compressionLevel = LZ4HC_CLEVEL_MAX; /* cap compression level */
- LZ4_streamHCPtr->internal_donotuse.compressionLevel = compressionLevel;
- LZ4_streamHCPtr->internal_donotuse.searchNum = LZ4HC_getSearchNum(compressionLevel);
+ LZ4_setCompressionLevel(LZ4_streamHCPtr, compressionLevel);
}
void LZ4_setCompressionLevel(LZ4_streamHC_t* LZ4_streamHCPtr, int compressionLevel)
{
- int const currentCLevel = LZ4_streamHCPtr->internal_donotuse.compressionLevel;
- int const minCLevel = currentCLevel < LZ4HC_CLEVEL_OPT_MIN ? 1 : LZ4HC_CLEVEL_OPT_MIN;
- int const maxCLevel = currentCLevel < LZ4HC_CLEVEL_OPT_MIN ? LZ4HC_CLEVEL_OPT_MIN-1 : LZ4HC_CLEVEL_MAX;
- compressionLevel = MIN(compressionLevel, minCLevel);
- compressionLevel = MAX(compressionLevel, maxCLevel);
+ if (compressionLevel < 1) compressionLevel = 1;
+ if (compressionLevel > LZ4HC_CLEVEL_MAX) compressionLevel = LZ4HC_CLEVEL_MAX;
LZ4_streamHCPtr->internal_donotuse.compressionLevel = compressionLevel;
}
@@ -648,10 +713,7 @@ int LZ4_loadDictHC (LZ4_streamHC_t* LZ4_streamHCPtr, const char* dictionary, int
}
LZ4HC_init (ctxPtr, (const BYTE*)dictionary);
ctxPtr->end = (const BYTE*)dictionary + dictSize;
- if (ctxPtr->compressionLevel >= LZ4HC_CLEVEL_OPT_MIN)
- LZ4HC_updateBinTree(ctxPtr, ctxPtr->end - MFLIMIT, ctxPtr->end - LASTLITERALS);
- else
- if (dictSize >= 4) LZ4HC_Insert (ctxPtr, ctxPtr->end-3);
+ if (dictSize >= 4) LZ4HC_Insert (ctxPtr, ctxPtr->end-3);
return dictSize;
}
@@ -660,10 +722,7 @@ int LZ4_loadDictHC (LZ4_streamHC_t* LZ4_streamHCPtr, const char* dictionary, int
static void LZ4HC_setExternalDict(LZ4HC_CCtx_internal* ctxPtr, const BYTE* newBlock)
{
- if (ctxPtr->compressionLevel >= LZ4HC_CLEVEL_OPT_MIN)
- LZ4HC_updateBinTree(ctxPtr, ctxPtr->end - MFLIMIT, ctxPtr->end - LASTLITERALS);
- else
- if (ctxPtr->end >= ctxPtr->base + 4) LZ4HC_Insert (ctxPtr, ctxPtr->end-3); /* Referencing remaining dictionary content */
+ if (ctxPtr->end >= ctxPtr->base + 4) LZ4HC_Insert (ctxPtr, ctxPtr->end-3); /* Referencing remaining dictionary content */
/* Only one memory segment for extDict, so any previous extDict is lost at this stage */
ctxPtr->lowLimit = ctxPtr->dictLimit;
@@ -717,8 +776,6 @@ int LZ4_compress_HC_continue (LZ4_streamHC_t* LZ4_streamHCPtr, const char* src,
int LZ4_compress_HC_continue_destSize (LZ4_streamHC_t* LZ4_streamHCPtr, const char* src, char* dst, int* srcSizePtr, int targetDestSize)
{
- LZ4HC_CCtx_internal* const ctxPtr = &LZ4_streamHCPtr->internal_donotuse;
- if (ctxPtr->compressionLevel >= LZ4HC_CLEVEL_OPT_MIN) LZ4HC_init(ctxPtr, (const BYTE*)src); /* not compatible with btopt implementation */
return LZ4_compressHC_continue_generic(LZ4_streamHCPtr, src, dst, srcSizePtr, targetDestSize, limitedDestSize);
}
diff --git a/lib/lz4hc.h b/lib/lz4hc.h
index 66d5636..d791062 100644
--- a/lib/lz4hc.h
+++ b/lib/lz4hc.h
@@ -39,7 +39,7 @@ extern "C" {
#endif
/* --- Dependency --- */
-/* note : lz4hc is not an independent module, it requires lz4.h/lz4.c for proper compilation */
+/* note : lz4hc requires lz4.h/lz4.c for compilation */
#include "lz4.h" /* stddef, LZ4LIB_API, LZ4_DEPRECATED */
@@ -54,12 +54,12 @@ extern "C" {
* Block Compression
**************************************/
/*! LZ4_compress_HC() :
- * Compress data from `src` into `dst`, using the more powerful but slower "HC" algorithm.
+ * Compress data from `src` into `dst`, using the more powerful but slower "HC" algorithm.
* `dst` must be already allocated.
- * Compression is guaranteed to succeed if `dstCapacity >= LZ4_compressBound(srcSize)` (see "lz4.h")
- * Max supported `srcSize` value is LZ4_MAX_INPUT_SIZE (see "lz4.h")
- * `compressionLevel` : Recommended values are between 4 and 9, although any value between 1 and LZ4HC_CLEVEL_MAX will work.
- * Values >LZ4HC_CLEVEL_MAX behave the same as LZ4HC_CLEVEL_MAX.
+ * Compression is guaranteed to succeed if `dstCapacity >= LZ4_compressBound(srcSize)` (see "lz4.h")
+ * Max supported `srcSize` value is LZ4_MAX_INPUT_SIZE (see "lz4.h")
+ * `compressionLevel` : any value between 1 and LZ4HC_CLEVEL_MAX will work.
+ * Values > LZ4HC_CLEVEL_MAX behave the same as LZ4HC_CLEVEL_MAX.
* @return : the number of bytes written into 'dst'
* or 0 if compression fails.
*/
@@ -72,12 +72,12 @@ LZ4LIB_API int LZ4_compress_HC (const char* src, char* dst, int srcSize, int dst
/*! LZ4_compress_HC_extStateHC() :
- * Same as LZ4_compress_HC(), but using an externally allocated memory segment for `state`.
+ * Same as LZ4_compress_HC(), but using an externally allocated memory segment for `state`.
* `state` size is provided by LZ4_sizeofStateHC().
- * Memory segment must be aligned on 8-bytes boundaries (which a normal malloc() will do properly).
+ * Memory segment must be aligned on 8-bytes boundaries (which a normal malloc() should do properly).
*/
-LZ4LIB_API int LZ4_compress_HC_extStateHC(void* state, const char* src, char* dst, int srcSize, int maxDstSize, int compressionLevel);
LZ4LIB_API int LZ4_sizeofStateHC(void);
+LZ4LIB_API int LZ4_compress_HC_extStateHC(void* state, const char* src, char* dst, int srcSize, int maxDstSize, int compressionLevel);
/*-************************************
@@ -87,10 +87,10 @@ LZ4LIB_API int LZ4_sizeofStateHC(void);
typedef union LZ4_streamHC_u LZ4_streamHC_t; /* incomplete type (defined later) */
/*! LZ4_createStreamHC() and LZ4_freeStreamHC() :
- * These functions create and release memory for LZ4 HC streaming state.
- * Newly created states are automatically initialized.
- * Existing states can be re-used several times, using LZ4_resetStreamHC().
- * These methods are API and ABI stable, they can be used in combination with a DLL.
+ * These functions create and release memory for LZ4 HC streaming state.
+ * Newly created states are automatically initialized.
+ * Existing states can be re-used several times, using LZ4_resetStreamHC().
+ * These methods are API and ABI stable, they can be used in combination with a DLL.
*/
LZ4LIB_API LZ4_streamHC_t* LZ4_createStreamHC(void);
LZ4LIB_API int LZ4_freeStreamHC (LZ4_streamHC_t* streamHCPtr);
@@ -123,13 +123,13 @@ LZ4LIB_API int LZ4_saveDictHC (LZ4_streamHC_t* streamHCPtr, char* safeBuffer, in
*/
- /*-*************************************
+/*-**************************************************************
* PRIVATE DEFINITIONS :
* Do not use these definitions.
* They are exposed to allow static allocation of `LZ4_streamHC_t`.
* Using these definitions makes the code vulnerable to potential API break when upgrading LZ4
- **************************************/
-#define LZ4HC_DICTIONARY_LOGSIZE 17 /* because of btopt, hc would only need 16 */
+ ****************************************************************/
+#define LZ4HC_DICTIONARY_LOGSIZE 16
#define LZ4HC_MAXD (1<<LZ4HC_DICTIONARY_LOGSIZE)
#define LZ4HC_MAXD_MASK (LZ4HC_MAXD - 1)
@@ -152,8 +152,7 @@ typedef struct
uint32_t dictLimit; /* below that point, need extDict */
uint32_t lowLimit; /* below that point, no more dict */
uint32_t nextToUpdate; /* index from which to continue dictionary update */
- uint32_t searchNum; /* only for optimal parser */
- uint32_t compressionLevel;
+ int compressionLevel;
} LZ4HC_CCtx_internal;
#else
@@ -169,13 +168,12 @@ typedef struct
unsigned int dictLimit; /* below that point, need extDict */
unsigned int lowLimit; /* below that point, no more dict */
unsigned int nextToUpdate; /* index from which to continue dictionary update */
- unsigned int searchNum; /* only for optimal parser */
int compressionLevel;
} LZ4HC_CCtx_internal;
#endif
-#define LZ4_STREAMHCSIZE (4*LZ4HC_HASHTABLESIZE + 2*LZ4HC_MAXD + 56) /* 393268 */
+#define LZ4_STREAMHCSIZE (4*LZ4HC_HASHTABLESIZE + 2*LZ4HC_MAXD + 56) /* 262200 */
#define LZ4_STREAMHCSIZE_SIZET (LZ4_STREAMHCSIZE / sizeof(size_t))
union LZ4_streamHC_u {
size_t table[LZ4_STREAMHCSIZE_SIZET];
@@ -197,7 +195,6 @@ union LZ4_streamHC_u {
/* see lz4.h LZ4_DISABLE_DEPRECATE_WARNINGS to turn off deprecation warnings */
/* deprecated compression functions */
-/* these functions will trigger warning messages in future releases */
LZ4LIB_API LZ4_DEPRECATED("use LZ4_compress_HC() instead") int LZ4_compressHC (const char* source, char* dest, int inputSize);
LZ4LIB_API LZ4_DEPRECATED("use LZ4_compress_HC() instead") int LZ4_compressHC_limitedOutput (const char* source, char* dest, int inputSize, int maxOutputSize);
LZ4LIB_API LZ4_DEPRECATED("use LZ4_compress_HC() instead") int LZ4_compressHC2 (const char* source, char* dest, int inputSize, int compressionLevel);
@@ -225,14 +222,15 @@ LZ4LIB_API LZ4_DEPRECATED("use LZ4_resetStreamHC() instead") int LZ4_resetStr
#endif /* LZ4_HC_H_19834876238432 */
-/*-************************************************
+
+/*-**************************************************
* !!!!! STATIC LINKING ONLY !!!!!
* Following definitions are considered experimental.
* They should not be linked from DLL,
* as there is no guarantee of API stability yet.
* Prototypes will be promoted to "stable" status
* after successfull usage in real-life scenarios.
- *************************************************/
+ ***************************************************/
#ifdef LZ4_HC_STATIC_LINKING_ONLY /* protection macro */
#ifndef LZ4_HC_SLO_098092834
#define LZ4_HC_SLO_098092834
@@ -258,17 +256,13 @@ int LZ4_compress_HC_destSize(void* LZ4HC_Data,
* @return : the number of bytes written into 'dst'
* or 0 if compression fails.
* `srcSizePtr` : value will be updated to indicate how much bytes were read from `src`.
- * Important : due to limitations, this prototype only works well up to cLevel < LZ4HC_CLEVEL_OPT_MIN
- * beyond that level, compression performance will be much reduced due to internal incompatibilities
*/
int LZ4_compress_HC_continue_destSize(LZ4_streamHC_t* LZ4_streamHCPtr,
const char* src, char* dst,
int* srcSizePtr, int targetDstSize);
/*! LZ4_setCompressionLevel() : v1.8.0 (experimental)
- * It's possible to change compression level after LZ4_resetStreamHC(), between 2 invocations of LZ4_compress_HC_continue*(),
- * but that requires to stay in the same mode (aka 1-10 or 11-12).
- * This function ensures this condition.
+ * It's possible to change compression level between 2 invocations of LZ4_compress_HC_continue*()
*/
void LZ4_setCompressionLevel(LZ4_streamHC_t* LZ4_streamHCPtr, int compressionLevel);
diff --git a/lib/lz4opt.h b/lib/lz4opt.h
index 584dc97..9917851 100644
--- a/lib/lz4opt.h
+++ b/lib/lz4opt.h
@@ -35,12 +35,6 @@
#define LZ4_OPT_NUM (1<<12)
-
-typedef struct {
- int off;
- int len;
-} LZ4HC_match_t;
-
typedef struct {
int price;
int off;
@@ -50,317 +44,286 @@ typedef struct {
/* price in bytes */
-LZ4_FORCE_INLINE size_t LZ4HC_literalsPrice(size_t litlen)
+LZ4_FORCE_INLINE int LZ4HC_literalsPrice(int const litlen)
{
- size_t price = litlen;
- if (litlen >= (size_t)RUN_MASK)
+ int price = litlen;
+ if (litlen >= (int)RUN_MASK)
price += 1 + (litlen-RUN_MASK)/255;
return price;
}
/* requires mlen >= MINMATCH */
-LZ4_FORCE_INLINE size_t LZ4HC_sequencePrice(size_t litlen, size_t mlen)
+LZ4_FORCE_INLINE int LZ4HC_sequencePrice(int litlen, int mlen)
{
- size_t price = 2 + 1; /* 16-bit offset + token */
+ int price = 1 + 2 ; /* token + 16-bit offset */
price += LZ4HC_literalsPrice(litlen);
- if (mlen >= (size_t)(ML_MASK+MINMATCH))
- price+= 1 + (mlen-(ML_MASK+MINMATCH))/255;
+ if (mlen >= (int)(ML_MASK+MINMATCH))
+ price += 1 + (mlen-(ML_MASK+MINMATCH))/255;
return price;
}
/*-*************************************
-* Binary Tree search
+* Match finder
***************************************/
-LZ4_FORCE_INLINE int LZ4HC_BinTree_InsertAndGetAllMatches (
- LZ4HC_CCtx_internal* ctx,
- const BYTE* const ip,
- const BYTE* const iHighLimit,
- size_t best_mlen,
- LZ4HC_match_t* matches,
- int* matchNum)
-{
- U16* const chainTable = ctx->chainTable;
- U32* const HashTable = ctx->hashTable;
- const BYTE* const base = ctx->base;
- const U32 dictLimit = ctx->dictLimit;
- const U32 current = (U32)(ip - base);
- const U32 lowLimit = (ctx->lowLimit + MAX_DISTANCE > current) ? ctx->lowLimit : current - (MAX_DISTANCE - 1);
- const BYTE* const dictBase = ctx->dictBase;
- const BYTE* match;
- int nbAttempts = ctx->searchNum;
- int mnum = 0;
- U16 *ptr0, *ptr1, delta0, delta1;
- U32 matchIndex;
- size_t matchLength = 0;
- U32* HashPos;
-
- if (ip + MINMATCH > iHighLimit) return 1;
-
- /* HC4 match finder */
- HashPos = &HashTable[LZ4HC_hashPtr(ip)];
- matchIndex = *HashPos;
- *HashPos = current;
-
- ptr0 = &DELTANEXTMAXD(current*2+1);
- ptr1 = &DELTANEXTMAXD(current*2);
- delta0 = delta1 = (U16)(current - matchIndex);
-
- while ((matchIndex < current) && (matchIndex>=lowLimit) && (nbAttempts)) {
- nbAttempts--;
- if (matchIndex >= dictLimit) {
- match = base + matchIndex;
- matchLength = LZ4_count(ip, match, iHighLimit);
- } else {
- const BYTE* vLimit = ip + (dictLimit - matchIndex);
- match = dictBase + matchIndex;
- if (vLimit > iHighLimit) vLimit = iHighLimit;
- matchLength = LZ4_count(ip, match, vLimit);
- if ((ip+matchLength == vLimit) && (vLimit < iHighLimit))
- matchLength += LZ4_count(ip+matchLength, base+dictLimit, iHighLimit);
- if (matchIndex+matchLength >= dictLimit)
- match = base + matchIndex; /* to prepare for next usage of match[matchLength] */
- }
-
- if (matchLength > best_mlen) {
- best_mlen = matchLength;
- if (matches) {
- if (matchIndex >= dictLimit)
- matches[mnum].off = (int)(ip - match);
- else
- matches[mnum].off = (int)(ip - (base + matchIndex)); /* virtual matchpos */
- matches[mnum].len = (int)matchLength;
- mnum++;
- }
- if (best_mlen > LZ4_OPT_NUM) break;
- }
-
- if (ip+matchLength >= iHighLimit) /* equal : no way to know if inf or sup */
- break; /* drop , to guarantee consistency ; miss a bit of compression, but other solutions can corrupt the tree */
-
- DEBUGLOG(6, "ip :%016llX", (U64)ip);
- DEBUGLOG(6, "match:%016llX", (U64)match);
- if (*(ip+matchLength) < *(match+matchLength)) {
- *ptr0 = delta0;
- ptr0 = &DELTANEXTMAXD(matchIndex*2);
- if (*ptr0 == (U16)-1) break;
- delta0 = *ptr0;
- delta1 += delta0;
- matchIndex -= delta0;
- } else {
- *ptr1 = delta1;
- ptr1 = &DELTANEXTMAXD(matchIndex*2+1);
- if (*ptr1 == (U16)-1) break;
- delta1 = *ptr1;
- delta0 += delta1;
- matchIndex -= delta1;
- }
- }
-
- *ptr0 = (U16)-1;
- *ptr1 = (U16)-1;
- if (matchNum) *matchNum = mnum;
- /* if (best_mlen > 8) return best_mlen-8; */
- if (!matchNum) return 1;
- return 1;
-}
-
-
-LZ4_FORCE_INLINE void LZ4HC_updateBinTree(LZ4HC_CCtx_internal* ctx, const BYTE* const ip, const BYTE* const iHighLimit)
-{
- const BYTE* const base = ctx->base;
- const U32 target = (U32)(ip - base);
- U32 idx = ctx->nextToUpdate;
- while(idx < target)
- idx += LZ4HC_BinTree_InsertAndGetAllMatches(ctx, base+idx, iHighLimit, 8, NULL, NULL);
-}
-
+typedef struct {
+ int off;
+ int len;
+} LZ4HC_match_t;
-/** Tree updater, providing best match */
-LZ4_FORCE_INLINE int LZ4HC_BinTree_GetAllMatches (
- LZ4HC_CCtx_internal* ctx,
- const BYTE* const ip, const BYTE* const iHighLimit,
- size_t best_mlen, LZ4HC_match_t* matches, const int fullUpdate)
+LZ4_FORCE_INLINE
+LZ4HC_match_t LZ4HC_FindLongerMatch(LZ4HC_CCtx_internal* const ctx,
+ const BYTE* ip, const BYTE* const iHighLimit,
+ int minLen, int nbSearches)
{
- int mnum = 0;
- if (ip < ctx->base + ctx->nextToUpdate) return 0; /* skipped area */
- if (fullUpdate) LZ4HC_updateBinTree(ctx, ip, iHighLimit);
- best_mlen = LZ4HC_BinTree_InsertAndGetAllMatches(ctx, ip, iHighLimit, best_mlen, matches, &mnum);
- ctx->nextToUpdate = (U32)(ip - ctx->base + best_mlen);
- return mnum;
-}
-
-
-#define SET_PRICE(pos, ml, offset, ll, cost) \
-{ \
- while (last_pos < pos) { opt[last_pos+1].price = 1<<30; last_pos++; } \
- opt[pos].mlen = (int)ml; \
- opt[pos].off = (int)offset; \
- opt[pos].litlen = (int)ll; \
- opt[pos].price = (int)cost; \
+ LZ4HC_match_t match = { 0 , 0 };
+ const BYTE* matchPtr = NULL;
+ /* note : LZ4HC_InsertAndGetWiderMatch() is able to modify the starting position of a match (*startpos),
+ * but this won't be the case here, as we define iLowLimit==ip,
+ * so LZ4HC_InsertAndGetWiderMatch() won't be allowed to search past ip */
+ int const matchLength = LZ4HC_InsertAndGetWiderMatch(ctx, ip, ip, iHighLimit, minLen, &matchPtr, &ip, nbSearches);
+ if (matchLength <= minLen) return match;
+ match.len = matchLength;
+ match.off = (int)(ip-matchPtr);
+ return match;
}
static int LZ4HC_compress_optimal (
LZ4HC_CCtx_internal* ctx,
const char* const source,
- char* dest,
+ char* dst,
int inputSize,
- int maxOutputSize,
+ int dstCapacity,
limitedOutput_directive limit,
+ int const nbSearches,
size_t sufficient_len,
- const int fullUpdate
+ int const fullUpdate
)
{
- LZ4HC_optimal_t opt[LZ4_OPT_NUM + 1]; /* this uses a bit too much stack memory to my taste ... */
- LZ4HC_match_t matches[LZ4_OPT_NUM + 1];
+#define TRAILING_LITERALS 3
+ LZ4HC_optimal_t opt[LZ4_OPT_NUM + TRAILING_LITERALS]; /* this uses a bit too much stack memory to my taste ... */
const BYTE* ip = (const BYTE*) source;
const BYTE* anchor = ip;
const BYTE* const iend = ip + inputSize;
const BYTE* const mflimit = iend - MFLIMIT;
- const BYTE* const matchlimit = (iend - LASTLITERALS);
- BYTE* op = (BYTE*) dest;
- BYTE* const oend = op + maxOutputSize;
+ const BYTE* const matchlimit = iend - LASTLITERALS;
+ BYTE* op = (BYTE*) dst;
+ BYTE* const oend = op + dstCapacity;
/* init */
DEBUGLOG(5, "LZ4HC_compress_optimal");
if (sufficient_len >= LZ4_OPT_NUM) sufficient_len = LZ4_OPT_NUM-1;
- ctx->end += inputSize;
- ip++;
/* Main Loop */
+ assert(ip - anchor < LZ4_MAX_INPUT_SIZE);
while (ip < mflimit) {
- size_t const llen = ip - anchor;
- size_t last_pos = 0;
- size_t match_num, cur, best_mlen, best_off;
- memset(opt, 0, sizeof(LZ4HC_optimal_t)); /* memset only the first one */
+ int const llen = (int)(ip - anchor);
+ int best_mlen, best_off;
+ int cur, last_match_pos = 0;
- match_num = LZ4HC_BinTree_GetAllMatches(ctx, ip, matchlimit, MINMATCH-1, matches, fullUpdate);
- if (!match_num) { ip++; continue; }
+ LZ4HC_match_t const firstMatch = LZ4HC_FindLongerMatch(ctx, ip, matchlimit, MINMATCH-1, nbSearches);
+ if (firstMatch.len==0) { ip++; continue; }
- if ((size_t)matches[match_num-1].len > sufficient_len) {
+ if ((size_t)firstMatch.len > sufficient_len) {
/* good enough solution : immediate encoding */
- best_mlen = matches[match_num-1].len;
- best_off = matches[match_num-1].off;
- cur = 0;
- last_pos = 1;
- goto encode;
+ int const firstML = firstMatch.len;
+ const BYTE* const matchPos = ip - firstMatch.off;
+ if ( LZ4HC_encodeSequence(&ip, &op, &anchor, firstML, matchPos, limit, oend) ) /* updates ip, op and anchor */
+ return 0; /* error */
+ continue;
}
- /* set prices using matches at position = 0 */
- { size_t matchNb;
- for (matchNb = 0; matchNb < match_num; matchNb++) {
- size_t mlen = (matchNb>0) ? (size_t)matches[matchNb-1].len+1 : MINMATCH;
- best_mlen = matches[matchNb].len; /* necessarily < sufficient_len < LZ4_OPT_NUM */
- for ( ; mlen <= best_mlen ; mlen++) {
- size_t const cost = LZ4HC_sequencePrice(llen, mlen) - LZ4HC_literalsPrice(llen);
- SET_PRICE(mlen, mlen, matches[matchNb].off, 0, cost); /* updates last_pos and opt[pos] */
- } } }
-
- if (last_pos < MINMATCH) { ip++; continue; } /* note : on clang at least, this test improves performance */
+ /* set prices for first positions (literals) */
+ { int rPos;
+ for (rPos = 0 ; rPos < MINMATCH ; rPos++) {
+ int const cost = LZ4HC_literalsPrice(llen + rPos);
+ opt[rPos].mlen = 1;
+ opt[rPos].off = 0;
+ opt[rPos].litlen = llen + rPos;
+ opt[rPos].price = cost;
+ DEBUGLOG(7, "rPos:%3i => price:%3i (litlen=%i) -- initial setup",
+ rPos, cost, opt[rPos].litlen);
+ } }
+ /* set prices using initial match */
+ { int mlen = MINMATCH;
+ int const matchML = firstMatch.len; /* necessarily < sufficient_len < LZ4_OPT_NUM */
+ int const offset = firstMatch.off;
+ assert(matchML < LZ4_OPT_NUM);
+ for ( ; mlen <= matchML ; mlen++) {
+ int const cost = LZ4HC_sequencePrice(llen, mlen);
+ opt[mlen].mlen = mlen;
+ opt[mlen].off = offset;
+ opt[mlen].litlen = llen;
+ opt[mlen].price = cost;
+ DEBUGLOG(7, "rPos:%3i => price:%3i (matchlen=%i) -- initial setup",
+ mlen, cost, mlen);
+ } }
+ last_match_pos = firstMatch.len;
+ { int addLit;
+ for (addLit = 1; addLit <= TRAILING_LITERALS; addLit ++) {
+ opt[last_match_pos+addLit].mlen = 1; /* literal */
+ opt[last_match_pos+addLit].off = 0;
+ opt[last_match_pos+addLit].litlen = addLit;
+ opt[last_match_pos+addLit].price = opt[last_match_pos].price + LZ4HC_literalsPrice(addLit);
+ DEBUGLOG(7, "rPos:%3i => price:%3i (litlen=%i) -- initial setup",
+ last_match_pos+addLit, opt[last_match_pos+addLit].price, addLit);
+ } }
/* check further positions */
- opt[0].mlen = opt[1].mlen = 1;
- for (cur = 1; cur <= last_pos; cur++) {
+ for (cur = 1; cur < last_match_pos; cur++) {
const BYTE* const curPtr = ip + cur;
-
- /* establish baseline price if cur is literal */
- { size_t price, litlen;
- if (opt[cur-1].mlen == 1) {
- /* no match at previous position */
- litlen = opt[cur-1].litlen + 1;
- if (cur > litlen) {
- price = opt[cur - litlen].price + LZ4HC_literalsPrice(litlen);
- } else {
- price = LZ4HC_literalsPrice(llen + litlen) - LZ4HC_literalsPrice(llen);
- }
- } else {
- litlen = 1;
- price = opt[cur - 1].price + LZ4HC_literalsPrice(1);
- }
-
- if (price < (size_t)opt[cur].price)
- SET_PRICE(cur, 1 /*mlen*/, 0 /*off*/, litlen, price); /* note : increases last_pos */
+ LZ4HC_match_t newMatch;
+
+ if (curPtr >= mflimit) break;
+ DEBUGLOG(7, "rPos:%u[%u] vs [%u]%u",
+ cur, opt[cur].price, opt[cur+1].price, cur+1);
+ if (fullUpdate) {
+ /* not useful to search here if next position has same (or lower) cost */
+ if ( (opt[cur+1].price <= opt[cur].price)
+ /* in some cases, next position has same cost, but cost rises sharply after, so a small match would still be beneficial */
+ && (opt[cur+MINMATCH].price < opt[cur].price + 3/*min seq price*/) )
+ continue;
+ } else {
+ /* not useful to search here if next position has same (or lower) cost */
+ if (opt[cur+1].price <= opt[cur].price) continue;
}
- if (cur == last_pos || curPtr >= mflimit) break;
+ DEBUGLOG(7, "search at rPos:%u", cur);
+ if (fullUpdate)
+ newMatch = LZ4HC_FindLongerMatch(ctx, curPtr, matchlimit, MINMATCH-1, nbSearches);
+ else
+ /* only test matches of minimum length; slightly faster, but misses a few bytes */
+ newMatch = LZ4HC_FindLongerMatch(ctx, curPtr, matchlimit, last_match_pos - cur, nbSearches);
+ if (!newMatch.len) continue;
- match_num = LZ4HC_BinTree_GetAllMatches(ctx, curPtr, matchlimit, MINMATCH-1, matches, fullUpdate);
- if ((match_num > 0) && (size_t)matches[match_num-1].len > sufficient_len) {
+ if ( ((size_t)newMatch.len > sufficient_len)
+ || (newMatch.len + cur >= LZ4_OPT_NUM) ) {
/* immediate encoding */
- best_mlen = matches[match_num-1].len;
- best_off = matches[match_num-1].off;
- last_pos = cur + 1;
+ best_mlen = newMatch.len;
+ best_off = newMatch.off;
+ last_match_pos = cur + 1;
goto encode;
}
- /* set prices using matches at position = cur */
- { size_t matchNb;
- for (matchNb = 0; matchNb < match_num; matchNb++) {
- size_t ml = (matchNb>0) ? (size_t)matches[matchNb-1].len+1 : MINMATCH;
- best_mlen = (cur + matches[matchNb].len < LZ4_OPT_NUM) ?
- (size_t)matches[matchNb].len : LZ4_OPT_NUM - cur;
-
- for ( ; ml <= best_mlen ; ml++) {
- size_t ll, price;
- if (opt[cur].mlen == 1) {
- ll = opt[cur].litlen;
- if (cur > ll)
- price = opt[cur - ll].price + LZ4HC_sequencePrice(ll, ml);
- else
- price = LZ4HC_sequencePrice(llen + ll, ml) - LZ4HC_literalsPrice(llen);
- } else {
- ll = 0;
- price = opt[cur].price + LZ4HC_sequencePrice(0, ml);
- }
-
- if (cur + ml > last_pos || price < (size_t)opt[cur + ml].price) {
- SET_PRICE(cur + ml, ml, matches[matchNb].off, ll, price);
- } } } }
- } /* for (cur = 1; cur <= last_pos; cur++) */
-
- best_mlen = opt[last_pos].mlen;
- best_off = opt[last_pos].off;
- cur = last_pos - best_mlen;
-
-encode: /* cur, last_pos, best_mlen, best_off must be set */
- opt[0].mlen = 1;
- while (1) { /* from end to beginning */
- size_t const ml = opt[cur].mlen;
- int const offset = opt[cur].off;
- opt[cur].mlen = (int)best_mlen;
- opt[cur].off = (int)best_off;
- best_mlen = ml;
- best_off = offset;
- if (ml > cur) break; /* can this happen ? */
- cur -= ml;
- }
+ /* before match : set price with literals at beginning */
+ { int const baseLitlen = opt[cur].litlen;
+ int litlen;
+ for (litlen = 1; litlen < MINMATCH; litlen++) {
+ int const price = opt[cur].price - LZ4HC_literalsPrice(baseLitlen) + LZ4HC_literalsPrice(baseLitlen+litlen);
+ int const pos = cur + litlen;
+ if (price < opt[pos].price) {
+ opt[pos].mlen = 1; /* literal */
+ opt[pos].off = 0;
+ opt[pos].litlen = baseLitlen+litlen;
+ opt[pos].price = price;
+ DEBUGLOG(7, "rPos:%3i => price:%3i (litlen=%i)",
+ pos, price, opt[pos].litlen);
+ } } }
+
+ /* set prices using match at position = cur */
+ { int const matchML = newMatch.len;
+ int ml = MINMATCH;
+
+ assert(cur + newMatch.len < LZ4_OPT_NUM);
+ for ( ; ml <= matchML ; ml++) {
+ int const pos = cur + ml;
+ int const offset = newMatch.off;
+ int price;
+ int ll;
+ DEBUGLOG(7, "testing price rPos %i (last_match_pos=%i)",
+ pos, last_match_pos);
+ if (opt[cur].mlen == 1) {
+ ll = opt[cur].litlen;
+ price = ((cur > ll) ? opt[cur - ll].price : 0)
+ + LZ4HC_sequencePrice(ll, ml);
+ } else {
+ ll = 0;
+ price = opt[cur].price + LZ4HC_sequencePrice(0, ml);
+ }
- /* encode all recorded sequences */
- cur = 0;
- while (cur < last_pos) {
- int const ml = opt[cur].mlen;
- int const offset = opt[cur].off;
- if (ml == 1) { ip++; cur++; continue; }
- cur += ml;
- if ( LZ4HC_encodeSequence(&ip, &op, &anchor, ml, ip - offset, limit, oend) ) return 0;
- }
+ if (pos > last_match_pos+TRAILING_LITERALS || price <= opt[pos].price) {
+ DEBUGLOG(7, "rPos:%3i => price:%3i (matchlen=%i)",
+ pos, price, ml);
+ assert(pos < LZ4_OPT_NUM);
+ if ( (ml == matchML) /* last pos of last match */
+ && (last_match_pos < pos) )
+ last_match_pos = pos;
+ opt[pos].mlen = ml;
+ opt[pos].off = offset;
+ opt[pos].litlen = ll;
+ opt[pos].price = price;
+ } } }
+ /* complete following positions with literals */
+ { int addLit;
+ for (addLit = 1; addLit <= TRAILING_LITERALS; addLit ++) {
+ opt[last_match_pos+addLit].mlen = 1; /* literal */
+ opt[last_match_pos+addLit].off = 0;
+ opt[last_match_pos+addLit].litlen = addLit;
+ opt[last_match_pos+addLit].price = opt[last_match_pos].price + LZ4HC_literalsPrice(addLit);
+ DEBUGLOG(7, "rPos:%3i => price:%3i (litlen=%i)", last_match_pos+addLit, opt[last_match_pos+addLit].price, addLit);
+ } }
+ } /* for (cur = 1; cur <= last_match_pos; cur++) */
+
+ best_mlen = opt[last_match_pos].mlen;
+ best_off = opt[last_match_pos].off;
+ cur = last_match_pos - best_mlen;
+
+encode: /* cur, last_match_pos, best_mlen, best_off must be set */
+ assert(cur < LZ4_OPT_NUM);
+ assert(last_match_pos >= 1); /* == 1 when only one candidate */
+ DEBUGLOG(6, "reverse traversal, looking for shortest path")
+ DEBUGLOG(6, "last_match_pos = %i", last_match_pos);
+ { int candidate_pos = cur;
+ int selected_matchLength = best_mlen;
+ int selected_offset = best_off;
+ while (1) { /* from end to beginning */
+ int const next_matchLength = opt[candidate_pos].mlen; /* can be 1, means literal */
+ int const next_offset = opt[candidate_pos].off;
+ DEBUGLOG(6, "pos %i: sequence length %i", candidate_pos, selected_matchLength);
+ opt[candidate_pos].mlen = selected_matchLength;
+ opt[candidate_pos].off = selected_offset;
+ selected_matchLength = next_matchLength;
+ selected_offset = next_offset;
+ if (next_matchLength > candidate_pos) break; /* last match elected, first match to encode */
+ assert(next_matchLength > 0); /* can be 1, means literal */
+ candidate_pos -= next_matchLength;
+ } }
+
+ /* encode all recorded sequences in order */
+ { int rPos = 0; /* relative position (to ip) */
+ while (rPos < last_match_pos) {
+ int const ml = opt[rPos].mlen;
+ int const offset = opt[rPos].off;
+ if (ml == 1) { ip++; rPos++; continue; } /* literal; note: can end up with several literals, in which case, skip them */
+ rPos += ml;
+ assert(ml >= MINMATCH);
+ assert((offset >= 1) && (offset <= MAX_DISTANCE));
+ if ( LZ4HC_encodeSequence(&ip, &op, &anchor, ml, ip - offset, limit, oend) ) /* updates ip, op and anchor */
+ return 0; /* error */
+ } }
} /* while (ip < mflimit) */
/* Encode Last Literals */
{ int lastRun = (int)(iend - anchor);
- if ((limit) && (((char*)op - dest) + lastRun + 1 + ((lastRun+255-RUN_MASK)/255) > (U32)maxOutputSize)) return 0; /* Check output limit */
- if (lastRun>=(int)RUN_MASK) { *op++=(RUN_MASK<<ML_BITS); lastRun-=RUN_MASK; for(; lastRun > 254 ; lastRun-=255) *op++ = 255; *op++ = (BYTE) lastRun; }
- else *op++ = (BYTE)(lastRun<<ML_BITS);
+ if ( (limit)
+ && (((char*)op - dst) + lastRun + 1 + ((lastRun+255-RUN_MASK)/255) > (U32)dstCapacity))
+ return 0; /* Check output limit */
+ if (lastRun >= (int)RUN_MASK) {
+ *op++=(RUN_MASK<<ML_BITS);
+ lastRun-=RUN_MASK;
+ for (; lastRun > 254 ; lastRun-=255) *op++ = 255;
+ *op++ = (BYTE) lastRun;
+ } else *op++ = (BYTE)(lastRun<<ML_BITS);
memcpy(op, anchor, iend - anchor);
op += iend-anchor;
}
/* End */
- return (int) ((char*)op-dest);
+ return (int) ((char*)op-dst);
}