zstd/compress/zstd_opt.c

292  * Provides the cost of the match part (offset + matchLength) of a sequence
316     /* match Length */
354     /* match Length */
431     const BYTE* match;
469             smallerPtr = nextPtr+1;               /* new "smaller" => larger of match */
486             match = base + matchIndex;
487             matchLength += ZSTD_count(ip+matchLength, match+matchLength, iend);
489             match = dictBase + matchIndex;
490             matchLength += ZSTD_count_2segments(ip+matchLength, match+matchLength, iend, dictEnd, prefixStart);
492                 match = base + matchIndex;   /* to prepare for next usage of match[matchLength] */
505         if (match[matchLength] < ip[matchLength]) {  /* necessarily within buffer */
506             /* match is smaller than current */
510             smallerPtr = nextPtr+1;               /* new "candidate" => larger than match, which was smaller than target */
513             /* match is larger than current */
588     U32 matchEndIdx = curr+8+1;   /* farthest referenced position of any match => detects repetitive patterns */
655     /* HC3 match finder */
662                 const BYTE* const match = base + matchIndex3;
663                 mlen = ZSTD_count(ip, match, iLimit);
665                 const BYTE* const match = dictBase + matchIndex3;
666                 mlen = ZSTD_count_2segments(ip, match, iLimit, dictEnd, prefixStart);
671                 DEBUGLOG(8, "found small match with hlog3, of length %u",
691         const BYTE* match;
697             match = base + matchIndex;
698             if (matchIndex >= dictLimit) assert(memcmp(match, ip, matchLength) == 0);  /* ensure early section of match is equal as expected */
699             matchLength += ZSTD_count(ip+matchLength, match+matchLength, iLimit);
701             match = dictBase + matchIndex;
702             assert(memcmp(match, ip, matchLength) == 0);  /* ensure early section of match is equal as expected */
703             matchLength += ZSTD_count_2segments(ip+matchLength, match+matchLength, iLimit, dictEnd, prefixStart);
705                 match = base + matchIndex;   /* prepare for match[matchLength] read */
709             DEBUGLOG(8, "found match of length %u at distance %u (offCode=%u)",
724         if (match[matchLength] < ip[matchLength]) {
725             /* match smaller than current */
729             smallerPtr = nextPtr+1;               /* new candidate => larger than match, which was smaller than current */
750             const BYTE* match = dmsBase + dictMatchIndex;
751             matchLength += ZSTD_count_2segments(ip+matchLength, match+matchLength, iLimit, dmsEnd, prefixStart);
753                 match = base + dictMatchIndex + dmsIndexDelta;   /* to prepare for next usage of match[matchLength] */
757                 DEBUGLOG(8, "found dms match of length %u at distance %u (offCode=%u)",
771             if (match[matchLength] < ip[matchLength]) {
775                 /* match is larger than current */
871     rawSeqStore_t seqStore;   /* External match candidates store for this block */
872     U32 startPosInBlock;      /* Start position of the current match candidate */
873     U32 endPosInBlock;        /* End position of the current match candidate */
874     U32 offset;               /* Offset of the match candidate */
900  * Calculates the beginning and end of the next match in the current block.
912     /* Setting match end position to MAX to ensure we never use an LDM during this block */
945         /* Match ends after the block ends, we can't use the whole match */
955  * Adds a match if it's long enough,
966     /* Ensure that current block position is not outside of the match */
975         DEBUGLOG(6, "ZSTD_optLdm_maybeAddMatch(): Adding ldm candidate match (offCode: %u matchLength %u) at block position=%u",
998              * at the end of a match from the ldm seq store, and will often be some bytes
1080         /* find first match */
1099             /* large match -> immediate encoding */
1109                     DEBUGLOG(6, "large match (%u>%u), immediate encoding",
1184             /* last match must start at a minimum distance of 8 from oend */
1207                     DEBUGLOG(7, "rPos:%u : no match found", cur);
1220                         cur -= (opt[cur].mlen==0) ? opt[cur].litlen : 0;  /* last sequence is actually only literals, fix cur to last match - note : may underflow, in which case, it's first sequence, and it's okay */
1222                         if (cur > ZSTD_OPT_NUM) cur = 0;   /* underflow => first match */
1233                     DEBUGLOG(7, "testing match %u => offCode=%4u, mlen=%2u, llen=%2u",
1264          * of the last match, and the last sequence. This avoids us having to