From: Yann Collet <cyan@fb.com>
Date: Tue, 29 May 2018 22:29:55 +0000 (-0700)
Subject: minor update of literal cost function
X-Git-Tag: v1.3.5~3^2~38^2
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=809f2f93229b3de57ea4dfab01feab2e699a7327;p=thirdparty%2Fzstd.git

minor update of literal cost function

just assert() there is no negative cost evaluation for literals
---

diff --git a/lib/compress/zstd_opt.c b/lib/compress/zstd_opt.c
index de745b6e6..46a5395ac 100644
--- a/lib/compress/zstd_opt.c
+++ b/lib/compress/zstd_opt.c
@@ -189,12 +189,11 @@ static U32 ZSTD_rawLiteralsCost(const BYTE* const literals, U32 const litLength,
         return (litLength*6) * BITCOST_MULTIPLIER;  /* 6 bit per literal - no statistic used */
 
     /* dynamic statistics */
-    {   U32 price, u;
-        for (u=0, price=0; u < litLength; u++) {
-            U32 const litWeight = WEIGHT(optPtr->litFreq[literals[u]], optLevel);
-            U32 litCost = optPtr->litSumBasePrice - litWeight;
-            //if (litCost < BITCOST_MULTIPLIER) litCost = BITCOST_MULTIPLIER;   /* minimum 1 bit per symbol (huffman) */
-            price += litCost;
+    {   U32 price = litLength * optPtr->litSumBasePrice;
+        U32 u;
+        for (u=0; u < litLength; u++) {
+            assert(WEIGHT(optPtr->litFreq[literals[u]], optLevel) <= optPtr->litSumBasePrice);   /* literal cost should never be negative */
+            price -= WEIGHT(optPtr->litFreq[literals[u]], optLevel);
         }
         return price;
     }