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[opt] Don't recompute repcodes while emitting sequences

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This commit is contained in:
Nick Terrell 2020-03-04 17:23:00 -08:00
parent c6caa2d04e
commit 0f9882deb9
1 changed files with 11 additions and 15 deletions
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26
lib/compress/zstd_opt.c
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@ -1017,6 +1017,17 @@ ZSTD_compressBlock_opt_generic(ZSTD_matchState_t* ms,
_shortestPath: /* cur, last_pos, best_mlen, best_off have to be set */
assert(opt[0].mlen == 0);
/* Set the next chunk's repcodes based on the repcodes of the beginning
* of the last match, and the last sequence. This avoids us having to
* update them while traversing the sequences.
*/
if (lastSequence.mlen != 0) {
repcodes_t reps = ZSTD_updateRep(opt[cur].rep, lastSequence.off, lastSequence.litlen==0);
memcpy(rep, &reps, sizeof(reps));
} else {
memcpy(rep, opt[cur].rep, sizeof(repcodes_t));
}
{ U32 const storeEnd = cur + 1;
U32 storeStart = storeEnd;
U32 seqPos = cur;
@ -1053,20 +1064,6 @@ _shortestPath: /* cur, last_pos, best_mlen, best_off have to be set */
continue; /* will finish */
}
/* repcodes update : like ZSTD_updateRep(), but update in place */
if (offCode >= ZSTD_REP_NUM) { /* full offset */
rep[2] = rep[1];
rep[1] = rep[0];
rep[0] = offCode - ZSTD_REP_MOVE;
} else { /* repcode */
U32 const repCode = offCode + (llen==0);
if (repCode) { /* note : if repCode==0, no change */
U32 const currentOffset = (repCode==ZSTD_REP_NUM) ? (rep[0] - 1) : rep[repCode];
if (repCode >= 2) rep[2] = rep[1];
rep[1] = rep[0];
rep[0] = currentOffset;
} }
assert(anchor + llen <= iend);
ZSTD_updateStats(optStatePtr, llen, anchor, offCode, mlen);
ZSTD_storeSeq(seqStore, llen, anchor, iend, offCode, mlen-MINMATCH);
@ -1075,7 +1072,6 @@ _shortestPath: /* cur, last_pos, best_mlen, best_off have to be set */
} }
ZSTD_setBasePrices(optStatePtr, optLevel);
}
} /* while (ip < ilimit) */
/* Return the last literals size */