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btopt0 : a bit faster and weaker

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This commit is contained in:
Yann Collet
2017-11-19 10:38:02 -08:00
parent e6da37c430
commit d100670045
1 changed files with 7 additions and 3 deletions
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lib/compress/zstd_opt.c
+7 -3
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@@ -553,11 +553,15 @@ size_t ZSTD_compressBlock_opt_generic(ZSTD_CCtx* ctx,
SET_PRICE(cur, 1/*mlen*/, 0/*offset*/, litlen, price, opt[cur-1].rep); SET_PRICE(cur, 1/*mlen*/, 0/*offset*/, litlen, price, opt[cur-1].rep);
} } } }
if (cur == last_pos) break;
/* last match must start at a minimum distance of 8 from oend */ /* last match must start at a minimum distance of 8 from oend */
if (inr > ilimit) continue; if (inr > ilimit) continue;
if (cur == last_pos) break;
if ( (optLevel==0) /*static*/
&& (opt[cur+1].price <= opt[cur].price) )
continue; /* skip unpromising positions; about ~+6% speed, -0.01 ratio */
{ U32 const ll0 = (opt[cur].mlen != 1); { U32 const ll0 = (opt[cur].mlen != 1);
U32 const litlen = (opt[cur].mlen == 1) ? opt[cur].litlen : 0; U32 const litlen = (opt[cur].mlen == 1) ? opt[cur].litlen : 0;
U32 const basePrice = (cur > litlen) ? opt[cur-litlen].price : 0; U32 const basePrice = (cur > litlen) ? opt[cur-litlen].price : 0;
@@ -600,7 +604,7 @@ size_t ZSTD_compressBlock_opt_generic(ZSTD_CCtx* ctx,
pos, price, opt[pos].price); pos, price, opt[pos].price);
SET_PRICE(pos, mlen, offset, litlen, price, repHistory); /* note : macro modifies last_pos */ SET_PRICE(pos, mlen, offset, litlen, price, repHistory); /* note : macro modifies last_pos */
} else { } else {
if (optLevel==0) break; /* gets ~+10% speed for about 0.01 ratio loss */ if (optLevel==0) break; /* gets ~+10% speed for about -0.01 ratio loss */
} }
} } } } } } } }