diff options
Diffstat (limited to 'lib/lz4hc.c')
-rw-r--r-- | lib/lz4hc.c | 53 |
1 files changed, 34 insertions, 19 deletions
diff --git a/lib/lz4hc.c b/lib/lz4hc.c index 4126ef8..3593da7 100644 --- a/lib/lz4hc.c +++ b/lib/lz4hc.c @@ -199,6 +199,7 @@ LZ4HC_reverseCountPattern(const BYTE* ip, const BYTE* const iLow, U32 pattern) } typedef enum { rep_untested, rep_not, rep_confirmed } repeat_state_e; +typedef enum { favorCompressionRatio=0, favorDecompressionSpeed } HCfavor_e; LZ4_FORCE_INLINE int LZ4HC_InsertAndGetWiderMatch ( @@ -211,7 +212,8 @@ LZ4HC_InsertAndGetWiderMatch ( const BYTE** startpos, const int maxNbAttempts, const int patternAnalysis, - const dictCtx_directive dict) + const dictCtx_directive dict, + const HCfavor_e favorDecSpeed) { U16* const chainTable = hc4->chainTable; U32* const HashTable = hc4->hashTable; @@ -240,7 +242,10 @@ LZ4HC_InsertAndGetWiderMatch ( while ((matchIndex>=lowLimit) && (nbAttempts)) { DEBUGLOG(7, "remaining attempts : %i", nbAttempts); nbAttempts--; - if (matchIndex >= dictLimit) { + assert(matchIndex < ipIndex); + if (favorDecSpeed && (ipIndex - matchIndex < 8)) { + /* do nothing */ + } else if (matchIndex >= dictLimit) { const BYTE* const matchPtr = base + matchIndex; assert(longest >= 1); if (LZ4_read16(iLowLimit + longest - 1) == LZ4_read16(matchPtr - delta + longest - 1)) { @@ -326,14 +331,12 @@ LZ4HC_InsertAndGetWiderMatch ( } } - { - U32 const nextOffset = DELTANEXTU16(dictCtx->chainTable, dictMatchIndex); + { U32 const nextOffset = DELTANEXTU16(dictCtx->chainTable, dictMatchIndex); dictMatchIndex -= nextOffset; matchIndex -= nextOffset; } } } - return longest; } @@ -349,7 +352,7 @@ int LZ4HC_InsertAndFindBestMatch(LZ4HC_CCtx_internal* const hc4, /* Index tabl /* 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, patternAnalysis, dict); + return LZ4HC_InsertAndGetWiderMatch(hc4, ip, ip, iLimit, MINMATCH-1, matchpos, &uselessPtr, maxNbAttempts, patternAnalysis, dict, favorCompressionRatio); } @@ -484,7 +487,7 @@ _Search2: if (ip+ml <= mflimit) ml2 = LZ4HC_InsertAndGetWiderMatch(ctx, ip + ml - 2, ip + 0, matchlimit, ml, &ref2, &start2, - maxNbAttempts, patternAnalysis, dict); + maxNbAttempts, patternAnalysis, dict, favorCompressionRatio); else ml2 = ml; @@ -531,7 +534,7 @@ _Search3: if (start2 + ml2 <= mflimit) ml3 = LZ4HC_InsertAndGetWiderMatch(ctx, start2 + ml2 - 3, start2, matchlimit, ml2, &ref3, &start3, - maxNbAttempts, patternAnalysis, dict); + maxNbAttempts, patternAnalysis, dict, favorCompressionRatio); else ml3 = ml2; @@ -651,12 +654,14 @@ _dest_overflow: return 0; } + static int LZ4HC_compress_optimal( LZ4HC_CCtx_internal* ctx, const char* const source, char* dst, int* srcSizePtr, int dstCapacity, int const nbSearches, size_t sufficient_len, const limitedOutput_directive limit, int const fullUpdate, - const dictCtx_directive dict); + const dictCtx_directive dict, + HCfavor_e favorDecSpeed); LZ4_FORCE_INLINE int LZ4HC_compress_generic_internal ( @@ -711,7 +716,9 @@ LZ4_FORCE_INLINE int LZ4HC_compress_generic_internal ( return LZ4HC_compress_optimal(ctx, src, dst, srcSizePtr, dstCapacity, cParam.nbSearches, cParam.targetLength, limit, - cLevel == LZ4HC_CLEVEL_MAX, dict); /* ultra mode */ + cLevel == LZ4HC_CLEVEL_MAX, /* ultra mode */ + dict, + favorDecompressionSpeed); } } @@ -1082,23 +1089,26 @@ LZ4_FORCE_INLINE LZ4HC_match_t LZ4HC_FindLongerMatch(LZ4HC_CCtx_internal* const ctx, const BYTE* ip, const BYTE* const iHighLimit, int minLen, int nbSearches, - const dictCtx_directive dict) + const dictCtx_directive dict, + const HCfavor_e favorDecSpeed) { 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, + int matchLength = LZ4HC_InsertAndGetWiderMatch(ctx, ip, ip, iHighLimit, minLen, &matchPtr, &ip, - nbSearches, 1 /* patternAnalysis */, dict); + nbSearches, 1 /* patternAnalysis */, dict, favorDecSpeed); if (matchLength <= minLen) return match; + if (favorDecSpeed) { + if ((matchLength>18) & (matchLength<=36)) matchLength=18; /* favor shortcut */ + } match.len = matchLength; match.off = (int)(ip-matchPtr); return match; } - static int LZ4HC_compress_optimal ( LZ4HC_CCtx_internal* ctx, const char* const source, @@ -1109,7 +1119,8 @@ static int LZ4HC_compress_optimal ( size_t sufficient_len, const limitedOutput_directive limit, int const fullUpdate, - const dictCtx_directive dict + const dictCtx_directive dict, + HCfavor_e favorDecSpeed ) { #define TRAILING_LITERALS 3 @@ -1125,6 +1136,7 @@ static int LZ4HC_compress_optimal ( BYTE* oend = op + dstCapacity; /* init */ + favorDecSpeed = favorCompressionRatio; DEBUGLOG(5, "LZ4HC_compress_optimal"); *srcSizePtr = 0; if (limit == limitedDestSize) oend -= LASTLITERALS; /* Hack for support LZ4 format restriction */ @@ -1137,7 +1149,7 @@ static int LZ4HC_compress_optimal ( int best_mlen, best_off; int cur, last_match_pos = 0; - LZ4HC_match_t const firstMatch = LZ4HC_FindLongerMatch(ctx, ip, matchlimit, MINMATCH-1, nbSearches, dict); + LZ4HC_match_t const firstMatch = LZ4HC_FindLongerMatch(ctx, ip, matchlimit, MINMATCH-1, nbSearches, dict, favorDecSpeed); if (firstMatch.len==0) { ip++; continue; } if ((size_t)firstMatch.len > sufficient_len) { @@ -1207,10 +1219,10 @@ static int LZ4HC_compress_optimal ( DEBUGLOG(7, "search at rPos:%u", cur); if (fullUpdate) - newMatch = LZ4HC_FindLongerMatch(ctx, curPtr, matchlimit, MINMATCH-1, nbSearches, dict); + newMatch = LZ4HC_FindLongerMatch(ctx, curPtr, matchlimit, MINMATCH-1, nbSearches, dict, favorDecSpeed); 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, dict); + newMatch = LZ4HC_FindLongerMatch(ctx, curPtr, matchlimit, last_match_pos - cur, nbSearches, dict, favorDecSpeed); if (!newMatch.len) continue; if ( ((size_t)newMatch.len > sufficient_len) @@ -1258,7 +1270,10 @@ static int LZ4HC_compress_optimal ( price = opt[cur].price + LZ4HC_sequencePrice(0, ml); } - if (pos > last_match_pos+TRAILING_LITERALS || price <= opt[pos].price) { + assert(opt[pos].price > 1); + assert((U32)favorDecSpeed <= 1); + if (pos > last_match_pos+TRAILING_LITERALS + || price <= opt[pos].price - (int)favorDecSpeed) { DEBUGLOG(7, "rPos:%3i => price:%3i (matchlen=%i)", pos, price, ml); assert(pos < LZ4_OPT_NUM); |