Merge pull request madler#72 from mtl1979/duphead

Don't update prev if old head is same as new.
Linaro · Jul 7, 2016 · 515fcf5 · 515fcf5
2 parents ceffbfa + 2b9bf9e
commit 515fcf5
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Showing 2 changed files with 10 additions and 4 deletions.
diff --git a/arch/x86/insert_string_sse.c b/arch/x86/insert_string_sse.c
@@ -39,9 +39,12 @@ Pos insert_string_sse(deflate_state *const s, const Pos str, unsigned int count)
         );
 #endif
 
-        ret = s->prev[(str+idx) & s->w_mask] = s->head[h & s->hash_mask];
-        s->head[h & s->hash_mask] = str+idx;
+        if (s->head[h & s->hash_mask] != str+idx) {
+            s->prev[(str+idx) & s->w_mask] = s->head[h & s->hash_mask];
+            s->head[h & s->hash_mask] = str+idx;
+        }
     }
+    ret = s->prev[(str+count-1) & s->w_mask];
     return ret;
 }
 #endif
diff --git a/deflate_p.h b/deflate_p.h
@@ -42,9 +42,12 @@ local inline Pos insert_string_c(deflate_state *const s, const Pos str, uInt cou
 
     for (idx = 0; idx < count; idx++) {
         UPDATE_HASH(s, s->ins_h, str+idx);
-        ret = s->prev[(str+idx) & s->w_mask] = s->head[s->ins_h];
-        s->head[s->ins_h] = str+idx;
+        if (s->head[s->ins_h] != str+idx) {
+            s->prev[(str+idx) & s->w_mask] = s->head[s->ins_h];
+            s->head[s->ins_h] = str+idx;
+        }
     }
+    ret = s->prev[(str+count-1) & s->w_mask];
     return ret;
 }