AuroraMiddleware/zstd
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best_off

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This commit is contained in:
inikep 2016-01-31 12:36:41 +01:00
parent 9bfb1a3357
commit c0dc4c361d
1 changed files with 61 additions and 17 deletions
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78
lib/zstd_opt.c
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@ -424,7 +424,7 @@ void ZSTD_compressBlock_opt_generic(ZSTD_CCtx* ctx,
LZ5HC_match_t matches[LZ5_OPT_NUM+1];
const uint8_t *inr;
int res, cur, cur2, cur_min, skip_num = 0;
int rep = 1, llen, litlen, price, offset, best_off, match_num, last_pos;
int rep = 1, llen, litlen, price, match_num, last_pos;
const int sufficient_len = 128; //ctx->params.sufficientLength;
const int faster_get_matches = (ctx->params.strategy == ZSTD_opt);
@ -437,7 +437,7 @@ void ZSTD_compressBlock_opt_generic(ZSTD_CCtx* ctx,
while (ip < ilimit) {
size_t mlen=0;
size_t best_mlen=0;
size_t offset=0;
size_t best_off=0;
const BYTE* start=ip+1;
memset(opt, 0, sizeof(LZ5HC_optimal_t));
last_pos = 0;
@ -472,7 +472,7 @@ void ZSTD_compressBlock_opt_generic(ZSTD_CCtx* ctx,
/* first search (depth 0) */
size_t mnum = getAllMatches(ctx, ip, iend, maxSearches, mls, matches);
if (mnum > 0 && matches[mnum-1].len > best_mlen)
best_mlen = matches[mnum-1].len, start = ip, offset=matches[mnum-1].off;
best_mlen = matches[mnum-1].len, start = ip, best_off=matches[mnum-1].off;
}
if (best_mlen < MINMATCH) {
@ -485,20 +485,20 @@ void ZSTD_compressBlock_opt_generic(ZSTD_CCtx* ctx,
if (depth>=1)
while (ip<ilimit) {
ip ++;
if ((offset) && (MEM_read32(ip) == MEM_read32(ip - rep_1))) {
if ((best_off) && (MEM_read32(ip) == MEM_read32(ip - rep_1))) {
size_t mlRep = ZSTD_count(ip+MINMATCH, ip+MINMATCH-rep_1, iend) + MINMATCH;
int gain2 = (int)(mlRep * 3);
int gain1 = (int)(best_mlen*3 - ZSTD_highbit((U32)offset+1) + 1);
int gain1 = (int)(best_mlen*3 - ZSTD_highbit((U32)best_off+1) + 1);
if ((mlRep >= MINMATCH) && (gain2 > gain1))
best_mlen = mlRep, offset = 0, start = ip;
best_mlen = mlRep, best_off = 0, start = ip;
}
{
size_t mnum = getAllMatches(ctx, ip, iend, maxSearches, mls, matches);
if (mnum > 0) {
int gain2 = (int)(matches[mnum-1].len*4 - ZSTD_highbit((U32)matches[mnum-1].off+1)); /* raw approx */
int gain1 = (int)(best_mlen*4 - ZSTD_highbit((U32)offset+1) + 4);
int gain1 = (int)(best_mlen*4 - ZSTD_highbit((U32)best_off+1) + 4);
if ((matches[mnum-1].len >= MINMATCH) && (gain2 > gain1)) {
best_mlen = matches[mnum-1].len, offset = matches[mnum-1].off, start = ip;
best_mlen = matches[mnum-1].len, best_off = matches[mnum-1].off, start = ip;
continue; /* search a better one */
}
}
@ -508,28 +508,72 @@ void ZSTD_compressBlock_opt_generic(ZSTD_CCtx* ctx,
}
/* catch up */
if (offset) {
while ((start>anchor) && (start>base+offset) && (start[-1] == start[-1-offset])) /* only search for offset within prefix */
if (best_off) {
while ((start>anchor) && (start>base+best_off) && (start[-1] == start[-1-best_off])) /* only search for offset within prefix */
{ start--; best_mlen++; }
rep_2 = rep_1; rep_1 = offset;
// rep_2 = rep_1; rep_1 = best_off;
}
cur = 0;
last_pos = 1;
/* store sequence */
_storeSequence:
_storeSequence: // cur, last_pos, best_mlen, best_off have to be set
for (int i = 1; i <= last_pos; i++)
LZ5_LOG_PARSER("%d: price[%d/%d]=%d off=%d mlen=%d litlen=%d rep=%d\n", (int)((char*)ip-source+i), i, last_pos, opt[i].price, opt[i].off, opt[i].mlen, opt[i].litlen, opt[i].rep);
LZ5_LOG_PARSER("%d: cur=%d/%d best_mlen=%d best_off=%d rep=%d\n", (int)((char*)ip-source+cur), cur, last_pos, best_mlen, best_off, opt[cur].rep);
opt[0].mlen = 1;
size_t offset;
while (cur >= 0)
{
size_t litLength = start - anchor;
ZSTD_storeSeq(seqStorePtr, litLength, anchor, offset, best_mlen-MINMATCH);
anchor = ip = start + best_mlen;
mlen = opt[cur].mlen;
offset = opt[cur].off;
opt[cur].mlen = best_mlen;
opt[cur].off = best_off;
best_mlen = mlen;
best_off = offset;
cur -= mlen;
}
for (int i = 0; i <= last_pos;)
{
LZ5_LOG_PARSER("%d: price2[%d/%d]=%d off=%d mlen=%d litlen=%d rep=%d\n", (int)((char*)ip-source+i), i, last_pos, opt[i].price, opt[i].off, opt[i].mlen, opt[i].litlen, opt[i].rep);
i += opt[i].mlen;
}
cur = 0;
while (cur < last_pos)
{
LZ5_LOG_PARSER("%d: price3[%d/%d]=%d off=%d mlen=%d litlen=%d rep=%d\n", (int)((char*)ip-source+cur), cur, last_pos, opt[cur].price, opt[cur].off, opt[cur].mlen, opt[cur].litlen, opt[cur].rep);
mlen = opt[cur].mlen;
if (mlen == 1) { ip++; cur++; continue; }
offset = opt[cur].off;
cur += mlen;
LZ5_LOG_ENCODE("%d: ENCODE literals=%d off=%d mlen=%d ", (int)((char*)ip-source), (int)(ip-anchor), (int)(offset), mlen);
size_t litLength = start - anchor;
ZSTD_storeSeq(seqStorePtr, litLength, anchor, offset, mlen-MINMATCH);
anchor = ip = start + mlen;
if (offset)
rep_2 = rep_1, rep_1 = offset;
LZ5_LOG_ENCODE("out=%d\n", (int)((char*)op - dest));
LZ5_LOG_PARSER("%d: offset=%d rep=%d\n", (int)((char*)ip-source), offset, rep);
}
/* check immediate repcode */
while ( (ip <= ilimit)
&& (MEM_read32(ip) == MEM_read32(ip - rep_2)) ) {
/* store sequence */
best_mlen = ZSTD_count(ip+MINMATCH, ip+MINMATCH-rep_2, iend);
offset = rep_2;
best_off = rep_2;
rep_2 = rep_1;
rep_1 = offset;
rep_1 = best_off;
ZSTD_storeSeq(seqStorePtr, 0, anchor, 0, best_mlen);
ip += best_mlen+MINMATCH;
anchor = ip;