Slightly improved compression speed

git-svn-id: https://lz4.googlecode.com/svn/trunk@41 650e7d94-2a16-8b24-b05c-7c0b3f6821cd

1 files changed, 13 insertions, 8 deletions

diff --git a/lz4.c b/lz4.c
index 1cf04d8..92fe61a 100644
--- a/lz4.c
+++ b/lz4.c
@@ -160,6 +160,7 @@ int LZ4_compressCtx(void** ctx,
 

 	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;

 	const int skipStrength = SKIPSTRENGTH;

 	U32 forwardH;

@@ -227,13 +228,16 @@ _next_match:
 		// Start Counting

 		ip+=MINMATCH; ref+=MINMATCH;   // MinMatch verified

 		anchor = ip;

-		while (A32(ref) == A32(ip))

+		while (ip<matchlimit-3)

 		{

-			ip+=4; ref+=4;

-			if (ip>matchlimit-4) { ref -= ip - (matchlimit-3); ip = matchlimit-3; break; }

+			int diff = A32(ref) ^ A32(ip);

+			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 (*ref == *ip) ip++;

+		if ((ip<(matchlimit-1)) && (A16(ref) == A16(ip))) { ip+=2; ref+=2; }

+		if ((ip<matchlimit) && (*ref == *ip)) ip++;

+_endCount:

 		len = (ip - anchor);

 		

 		// Encode MatchLength

@@ -298,6 +302,7 @@ int LZ4_compress64kCtx(void** ctx,
 

 	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;

 	const int skipStrength = SKIPSTRENGTH;

 	U32 forwardH;

@@ -366,9 +371,9 @@ _next_match:
 		anchor = ip;

 		while (ip<matchlimit-3)

 		{

-			if (A32(ref) == A32(ip)) { ip+=4; ref+=4; continue; }

-			if (A16(ref) == A16(ip)) { ip+=2; ref+=2; }

-			if (*ref == *ip) ip++;

+			int diff = A32(ref) ^ A32(ip);

+			if (!diff) { ip+=4; ref+=4; continue; }

+			ip += DeBruijnBytePos[((U32)((diff & -diff) * 0x077CB531U)) >> 27];

 			goto _endCount;

 		}

 		if ((ip<(matchlimit-1)) && (A16(ref) == A16(ip))) { ip+=2; ref+=2; }