From: senhuang42 <senhuang96@fb.com>
Date: Wed, 30 Sep 2020 23:45:40 +0000 (-0400)
Subject: Adjustments to ldm_calculateMatchRange() to calculate bounds correctly
X-Git-Tag: v1.4.7~57^2~22
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=7348b40a87c61307c026ae5291202f22327059e9;p=thirdparty%2Fzstd.git

Adjustments to ldm_calculateMatchRange() to calculate bounds correctly
---

diff --git a/lib/compress/zstd_opt.c b/lib/compress/zstd_opt.c
index 9e38996e3..5f7466b9b 100644
--- a/lib/compress/zstd_opt.c
+++ b/lib/compress/zstd_opt.c
@@ -799,29 +799,29 @@ static void ldm_calculateMatchRange(rawSeqStore_t* ldmSeqStore,
                             U32* matchOffset, U32 currPosInBlock,
                             U32 remainingBytes, U32 currBlockEndPos) {
     rawSeq currSeq = ldmSeqStore->seq[ldmSeqStore->pos];
-    U32 blockPosInSequence = ldmSeqStore->posInSequence + currPosInBlock;
-    U32 literalsBytesLeft = blockPosInSequence < currSeq.litLength ?
-                                currSeq.litLength - blockPosInSequence : 0;
-    /* In this case, the match is further in the block than currPosInBlock */
+    U32 literalsBytesLeft = (ldmSeqStore->posInSequence < currSeq.litLength) ?
+                                    currSeq.litLength - ldmSeqStore->posInSequence :
+                                    0;
+    /* In this case, the match is further in the block than currPosInBlock, and we are
+       currently in the literals section of the LDM */
     if (literalsBytesLeft) {
         if (literalsBytesLeft >= remainingBytes) {
             /* If there are more literal bytes than bytes remaining in block, no ldm */
             *matchStartPosInBlock = UINT_MAX;
             *matchEndPosInBlock = UINT_MAX;
-            ldmSeqStore->pos++;
-            ldmSeqStore->posInSequence = 0;
+            ldm_moveForwardBytesInSeqStore(ldmSeqStore, remainingBytes);
             return;
         }  
     }
 
-    *matchStartPosInBlock = currPosInBlock + literalsBytesLeft;
+    *matchStartPosInBlock = currPosInBlock + currSeq.litLength;
     *matchEndPosInBlock = *matchStartPosInBlock + currSeq.matchLength;
     *matchOffset = currSeq.offset;
 
     /* Match ends after the block ends, we can't use the whole match */
     if (*matchEndPosInBlock > currBlockEndPos) {
         *matchEndPosInBlock = currBlockEndPos;
-        ldmSeqStore->posInSequence += (currBlockEndPos - currPosInBlock);
+        ldm_moveForwardBytesInSeqStore(ldmSeqStore, currBlockEndPos - currPosInBlock);
     } else {
         /* We can use the entire match */
         ldmSeqStore->posInSequence = 0;