ddidderr/zstd-rs
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minor CRatio improvement

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This commit is contained in:
Yann Collet
2015-11-06 18:28:02 +01:00
parent 47cfa9a985
commit 9b8e453713
2 changed files with 18 additions and 11 deletions
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lib/zstdhc.c
+16 -9
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@@ -655,6 +655,7 @@ size_t ZSTD_HC_compressBlock_lazy_generic(ZSTD_HC_CCtx* ctx,
/* let's try to find a better solution */
start = ip;
while ((start>anchor) && (start-offset>ctx->base) && (start[-1] == start[-1-offset])) { start--; matchLength++; } /* catch up */
while (ip<ilimit)
{
@@ -670,11 +671,15 @@ size_t ZSTD_HC_compressBlock_lazy_generic(ZSTD_HC_CCtx* ctx,
{
size_t offset2=999999;
size_t ml2 = searchMax(ctx, ip, iend, &offset2, maxSearches, mls);
int gain2 = (int)(ml2*(3+deep) - ZSTD_highbit((U32)offset2+1)); /* raw approx */
int gain1 = (int)(matchLength*(3+deep) - ZSTD_highbit((U32)offset+1) + (3+deep));
const BYTE* start2 = ip;
int gain1, gain2;
if (ml2)
while ((start2>anchor) && (start2-offset2>ctx->base) && (start2[-1] == start2[-1-offset2])) { start2--; ml2++; } /* catch up */
gain2 = (int)(ml2*(3+deep) - ZSTD_highbit((U32)offset2+1)); /* raw approx */
gain1 = (int)(matchLength*(3+deep) - ZSTD_highbit((U32)offset+1) + (3+deep));
if (gain2 > gain1)
{
matchLength = ml2, offset = offset2, start = ip;
matchLength = ml2, offset = offset2, start = start2;
continue; /* search a better one */
}
}
@@ -694,12 +699,16 @@ size_t ZSTD_HC_compressBlock_lazy_generic(ZSTD_HC_CCtx* ctx,
{
size_t offset2=999999;
size_t ml2 = searchMax(ctx, ip, iend, &offset2, maxSearches, mls);
int gain2 = (int)(ml2*4 - ZSTD_highbit((U32)offset2+1)); /* raw approx */
int gain1 = (int)(matchLength*4 - ZSTD_highbit((U32)offset+1) + 7);
const BYTE* start2 = ip;
int gain1, gain2;
if (ml2)
while ((start2>anchor) && (start2-offset2>ctx->base) && (start2[-1] == start2[-1-offset2])) { start2--; ml2++; } /* catch up */
gain2 = (int)(ml2*(3+deep) - ZSTD_highbit((U32)offset2+1)); /* raw approx */
gain1 = (int)(matchLength*(3+deep) - ZSTD_highbit((U32)offset+1) + (3+deep));
if (gain2 > gain1)
{
matchLength = ml2, offset = offset2, start = ip;
continue;
matchLength = ml2, offset = offset2, start = start2;
continue; /* search a better one */
}
}
}
@@ -707,8 +716,6 @@ size_t ZSTD_HC_compressBlock_lazy_generic(ZSTD_HC_CCtx* ctx,
}
/* store sequence */
if (offset)
while ((start>anchor) && (start-offset>ctx->base) && (start[-1] == start[-1-offset])) { start--; matchLength++; } /* catch up */
{
size_t litLength = start - anchor;
if (offset) offset_1 = offset;