From: Yann Collet <cyan@fb.com>
Date: Fri, 7 Jan 2022 21:51:28 +0000 (-0800)
Subject: enforce a minimum price of 1 bit per literal in the optimal parser
X-Git-Tag: v1.5.4^2~273^2~2
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=9e1b4828e56a028efa0efdd7c30a58e6dd48c8c1;p=thirdparty%2Fzstd.git

enforce a minimum price of 1 bit per literal in the optimal parser
---

diff --git a/lib/compress/zstd_opt.c b/lib/compress/zstd_opt.c
index 1b1ddad42..2c48ae55e 100644
--- a/lib/compress/zstd_opt.c
+++ b/lib/compress/zstd_opt.c
@@ -255,11 +255,13 @@ 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 = litLength * optPtr->litSumBasePrice;
+    {   U32 price = 0;
         U32 u;
         for (u=0; u < litLength; u++) {
+            U32 litPrice = optPtr->litSumBasePrice - WEIGHT(optPtr->litFreq[literals[u]], optLevel);
             assert(WEIGHT(optPtr->litFreq[literals[u]], optLevel) <= optPtr->litSumBasePrice);   /* literal cost should never be negative */
-            price -= WEIGHT(optPtr->litFreq[literals[u]], optLevel);
+            if (litPrice < BITCOST_MULTIPLIER) litPrice = BITCOST_MULTIPLIER;
+            price += litPrice;
         }
         return price;
     }