From: Yann Collet <cyan@fb.com>
Date: Sat, 5 May 2018 20:46:45 +0000 (-0700)
Subject: fixed SC.opt integration with regular HC parser
X-Git-Tag: upstream/1.9.3~8^2^2~5
X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=d097bf93f853ddefdd05321d65cf7b90e3171c14;p=platform%2Fupstream%2Flz4.git

fixed SC.opt integration with regular HC parser

Only enabled when searching forward.

note : it slighly improves compression ratio,
but measurably decreases speed.
Trade-off to analyse.
---

diff --git a/lib/lz4hc.c b/lib/lz4hc.c
index 7e2fcb3..0f37f42 100644
--- a/lib/lz4hc.c
+++ b/lib/lz4hc.c
@@ -280,9 +280,9 @@ LZ4HC_InsertAndGetWiderMatch (
                     *startpos = ip + back;
         }   }   }
 
-        if (mlt == longest) {  /* better match => select a better chain */
-            assert(longest >= MINMATCH);
-            if (1 && matchIndex + longest <= ipIndex) {
+        if ( lookBackLength==0  /* search forward only */
+          && mlt==longest) {    /* better match => select a better chain */
+            if (matchIndex + longest <= ipIndex) {
                 U32 distanceToNextMatch = 1;
                 int pos;
                 for (pos = 0; pos <= longest - MINMATCH; pos++) {
@@ -301,7 +301,7 @@ LZ4HC_InsertAndGetWiderMatch (
         }
 
         {   U32 const distNextMatch = DELTANEXTU16(chainTable, matchIndex);
-            if (1 && patternAnalysis && distNextMatch==1 && matchChainPos==0) {
+            if (patternAnalysis && distNextMatch==1 && matchChainPos==0) {
                 U32 const matchCandidateIdx = matchIndex-1;
                 /* may be a repeated pattern */
                 if (repeat == rep_untested) {