Corrected issue 3 in compression function. Update is recommended.

git-svn-id: https://lz4.googlecode.com/svn/trunk@26 650e7d94-2a16-8b24-b05c-7c0b3f6821cd

1 files changed, 9 insertions, 7 deletions

diff --git a/lz4.c b/lz4.c
index fdf4fdd..ffc97b3 100644
--- a/lz4.c
+++ b/lz4.c
@@ -66,6 +66,7 @@
 // Constants

 //**************************************

 #define MINMATCH 4

+#define MINLENGTH 6

 #define SKIPSTRENGTH 6

 #define STACKLIMIT 13

 #define HEAPMODE (HASH_LOG>STACKLIMIT)  // Defines if memory is allocated into the stack (local variable), or into the heap (malloc()).

@@ -118,7 +119,8 @@ int LZ4_compressCtx(void** ctx,
 	const BYTE* ip = (BYTE*) source;       

 	const BYTE* anchor = ip;

 	const BYTE* const iend = ip + isize;

-	const BYTE* const ilimit = iend - MINMATCH;

+	const BYTE* const ilm = iend - 1;

+	const BYTE* const ilimit = iend - MINMATCH - 1;

 

 	BYTE* op = (BYTE*) dest;

 	BYTE* token;

@@ -130,6 +132,7 @@ int LZ4_compressCtx(void** ctx,
 

 

 	// Init 

+	if (isize<MINLENGTH) goto _last_literals;

 #if HEAPMODE

 	if (*ctx == NULL) 

 	{

@@ -190,15 +193,15 @@ _next_match:
 		// Start Counting

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

 		anchor = ip;

-		while (ip<(iend-3))

+		while (ip<(iend-4))

 		{

 			if (*(U32*)ref == *(U32*)ip) { ip+=4; ref+=4; continue; }

 			if (*(U16*)ref == *(U16*)ip) { ip+=2; ref+=2; }

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

 			goto _endCount;

 		}

-		if ((ip<(iend-1)) && (*(U16*)ref == *(U16*)ip)) { ip+=2; ref+=2; }

-		if ((ip<iend) && (*ref == *ip)) ip++;

+		if ((ip<(iend-2)) && (*(U16*)ref == *(U16*)ip)) { ip+=2; ref+=2; }

+		if ((ip<iend-1) && (*ref == *ip)) ip++;

 _endCount:

 		len = (ip - anchor);

 		

@@ -207,7 +210,7 @@ _endCount:
 		else *token += len;	

 

 		// Test end of chunk

-		if (ip > ilimit) { anchor = ip;  break; }

+		if (ip > ilimit-1) { anchor = ip;  break; }

 

 		// Test next position

 		ref = HashTable[HASH_VALUE(ip)];

@@ -221,14 +224,13 @@ _endCount:
 

 _last_literals:

 	// Encode Last Literals

-	if (anchor < iend)

 	{

 		int lastLitRun = iend - anchor;

 		if (lastLitRun>=(int)RUN_MASK) { *op++=(RUN_MASK<<ML_BITS); lastLitRun-=RUN_MASK; for(; lastLitRun > 254 ; lastLitRun-=255) *op++ = 255; *op++ = (BYTE) lastLitRun; } 

 		else *op++ = (lastLitRun<<ML_BITS);

 		while (anchor < iend - 3) { *(U32*)op = *(U32*)anchor; op+=4; anchor+=4; }

 		while (anchor < iend ) *op++ = *anchor++;

-	}

+	} 

 

 	// End

 	return (int) (((char*)op)-dest);