From d9bf974023d85f68b32b8c36052f4926f0478182 Mon Sep 17 00:00:00 2001
From: "yann.collet.73@gmail.com"
 <yann.collet.73@gmail.com@650e7d94-2a16-8b24-b05c-7c0b3f6821cd>
Date: Tue, 20 Sep 2011 10:01:23 +0000
Subject: [PATCH] Small compression speed improvement

git-svn-id: https://lz4.googlecode.com/svn/trunk@24 650e7d94-2a16-8b24-b05c-7c0b3f6821cd
---
 lz4.c | 43 +++++++++++++++++++++++++++----------------
 1 file changed, 27 insertions(+), 16 deletions(-)

diff --git a/lz4.c b/lz4.c
index 534b42b..54895a6 100644
--- a/lz4.c
+++ b/lz4.c
@@ -67,6 +67,7 @@
 //**************************************
 #define MINMATCH 4
 #define SKIPSTRENGTH 6
+#define HEAPLIMIT 13
 
 #define MAXD_LOG 16
 #define MAX_DISTANCE ((1 << MAXD_LOG) - 1)
@@ -106,8 +107,12 @@ int LZ4_compressCtx(void** ctx,
 				 char* dest,
 				 int isize)
 {	
+#if HASH_LOG>HEAPLIMIT
 	struct refTables *srt = (struct refTables *) (*ctx);
 	const BYTE**  HashTable;
+#else
+	const BYTE* HashTable[HASHTABLESIZE] = {0};
+#endif
 
 	const BYTE* ip = (BYTE*) source;       
 	const BYTE* anchor = ip;
@@ -124,6 +129,7 @@ int LZ4_compressCtx(void** ctx,
 
 
 	// Init 
+#if HASH_LOG>HEAPLIMIT
 	if (*ctx == NULL) 
 	{
 		srt = (struct refTables *) malloc ( sizeof(struct refTables) );
@@ -131,6 +137,7 @@ int LZ4_compressCtx(void** ctx,
 	}
 	HashTable = srt->hashTable;
 	memset((void*)HashTable, 0, sizeof(srt->hashTable));
+#endif
 
 
 	// First Byte
@@ -138,26 +145,26 @@ int LZ4_compressCtx(void** ctx,
 	ip++; forwardH = HASH_VALUE(ip);
 	
 	// Main Loop
-    for ( ; ; ) 
-	{
-		int segmentSize = (1U << skipStrength) + 3;
-		const BYTE* forwardIp = ip;
-		const BYTE* ref;
-
+    for ( ; ; ) 
+	{
+		int segmentSize = (1U << skipStrength) + 3;
+		const BYTE* forwardIp = ip;
+		const BYTE* ref;
+
 		// Find a match
-		do {
-			U32 h = forwardH;
-			int skipped = segmentSize++ >> skipStrength;
-			ip = forwardIp;
-			forwardIp = ip + skipped;
-
-			if (forwardIp > ilimit) { goto _last_literals; }
+		do {
+			U32 h = forwardH;
+			int skipped = segmentSize++ >> skipStrength;
+			ip = forwardIp;
+			forwardIp = ip + skipped;
+
+			if (forwardIp > ilimit) { goto _last_literals; }
 
 			forwardH = HASH_VALUE(forwardIp);
 			ref = HashTable[h];
 			HashTable[h] = ip;
-
-		} while ((ref < ip - MAX_DISTANCE) || (*(U32*)ref != *(U32*)ip));
+
+		} while ((ref < ip - MAX_DISTANCE) || (*(U32*)ref != *(U32*)ip));
 
 		// Catch up
 		while ((ip>anchor) && (ref>(BYTE*)source) && (ip[-1]==ref[-1])) { ip--; ref--; }  
@@ -230,15 +237,19 @@ int LZ4_compress(char* source,
 				 char* dest,
 				 int isize)
 {
+#if HASH_LOG>HEAPLIMIT
 	void* ctx = malloc(sizeof(struct refTables));
 	int result = LZ4_compressCtx(&ctx, source, dest, isize);
 	free(ctx);
-
 	return result;
+#else
+	return LZ4_compressCtx(NULL, source, dest, isize);
+#endif
 }
 
 
 
+
 //****************************
 // Decompression CODE
 //****************************
-- 
2.7.4