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Slightly improved compression speed

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git-svn-id: https://lz4.googlecode.com/svn/trunk@41 650e7d94-2a16-8b24-b05c-7c0b3f6821cd
This commit is contained in:
yann.collet.73@gmail.com 2011-11-21 23:56:21 +00:00
parent 70ba2c463f
commit bf12ca9a1e
1 changed files with 13 additions and 8 deletions
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21
lz4.c
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@ -160,6 +160,7 @@ int LZ4_compressCtx(void** ctx,
BYTE* op = (BYTE*) dest; BYTE* op = (BYTE*) dest;
const size_t DeBruijnBytePos[32] = { 0, 0, 3, 0, 3, 1, 3, 0, 3, 2, 2, 1, 3, 2, 0, 1, 3, 3, 1, 2, 2, 2, 2, 0, 3, 1, 2, 0, 1, 0, 1, 1 };
int len, length; int len, length;
const int skipStrength = SKIPSTRENGTH; const int skipStrength = SKIPSTRENGTH;
U32 forwardH; U32 forwardH;
@ -227,13 +228,16 @@ _next_match:
// Start Counting // Start Counting
ip+=MINMATCH; ref+=MINMATCH; // MinMatch verified ip+=MINMATCH; ref+=MINMATCH; // MinMatch verified
anchor = ip; anchor = ip;
while (A32(ref) == A32(ip)) while (ip<matchlimit-3)
{ {
ip+=4; ref+=4; int diff = A32(ref) ^ A32(ip);
if (ip>matchlimit-4) { ref -= ip - (matchlimit-3); ip = matchlimit-3; break; } if (!diff) { ip+=4; ref+=4; continue; }
ip += DeBruijnBytePos[((U32)((diff & -diff) * 0x077CB531U)) >> 27];
goto _endCount;
} }
if (A16(ref) == A16(ip)) { ip+=2; ref+=2; } if ((ip<(matchlimit-1)) && (A16(ref) == A16(ip))) { ip+=2; ref+=2; }
if (*ref == *ip) ip++; if ((ip<matchlimit) && (*ref == *ip)) ip++;
_endCount:
len = (ip - anchor); len = (ip - anchor);
// Encode MatchLength // Encode MatchLength
@ -298,6 +302,7 @@ int LZ4_compress64kCtx(void** ctx,
BYTE* op = (BYTE*) dest; BYTE* op = (BYTE*) dest;
const size_t DeBruijnBytePos[32] = { 0, 0, 3, 0, 3, 1, 3, 0, 3, 2, 2, 1, 3, 2, 0, 1, 3, 3, 1, 2, 2, 2, 2, 0, 3, 1, 2, 0, 1, 0, 1, 1 };
int len, length; int len, length;
const int skipStrength = SKIPSTRENGTH; const int skipStrength = SKIPSTRENGTH;
U32 forwardH; U32 forwardH;
@ -366,9 +371,9 @@ _next_match:
anchor = ip; anchor = ip;
while (ip<matchlimit-3) while (ip<matchlimit-3)
{ {
if (A32(ref) == A32(ip)) { ip+=4; ref+=4; continue; } int diff = A32(ref) ^ A32(ip);
if (A16(ref) == A16(ip)) { ip+=2; ref+=2; } if (!diff) { ip+=4; ref+=4; continue; }
if (*ref == *ip) ip++; ip += DeBruijnBytePos[((U32)((diff & -diff) * 0x077CB531U)) >> 27];
goto _endCount; goto _endCount;
} }
if ((ip<(matchlimit-1)) && (A16(ref) == A16(ip))) { ip+=2; ref+=2; } if ((ip<(matchlimit-1)) && (A16(ref) == A16(ip))) { ip+=2; ref+=2; }