From: Yann Collet <yann.collet.73@gmail.com>
Date: Tue, 25 Aug 2015 21:56:42 +0000 (+0100)
Subject: Fixed : compression error on some specific distribution
X-Git-Tag: v0.1.1^2~7
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=c7055675225e9d67e4094019d58eabe9275acd97;p=thirdparty%2Fzstd.git

Fixed : compression error on some specific distribution
---

diff --git a/lib/fse.c b/lib/fse.c
index 2c55a5635..be3919f45 100644
--- a/lib/fse.c
+++ b/lib/fse.c
@@ -1904,11 +1904,17 @@ static U32 HUF_setMaxHeight(nodeElt* huffNode, U32 lastNonNull, U32 maxNbBits)
                 if (rankLast[nBitsToDecrease-1] == noOne)
                     rankLast[nBitsToDecrease-1] = rankLast[nBitsToDecrease];   // now there is one elt
                 huffNode[rankLast[nBitsToDecrease]].nbBits ++;
-                rankLast[nBitsToDecrease]--;
-				if (huffNode[rankLast[nBitsToDecrease]].nbBits != maxNbBits-nBitsToDecrease)
-                    rankLast[nBitsToDecrease] = noOne;   // rank list emptied
+                if (rankLast[nBitsToDecrease] > 0)
+                {
+                    rankLast[nBitsToDecrease]--;
+                    if (huffNode[rankLast[nBitsToDecrease]].nbBits != maxNbBits-nBitsToDecrease)
+                        rankLast[nBitsToDecrease] = noOne;   // rank list emptied
+                }
+                else
+                     rankLast[nBitsToDecrease] = noOne;   // rank list emptied
             }
-			while (totalCost < 0)   // Sometimes, cost correction overshoot
+
+			while (totalCost < 0)   /* Sometimes, cost correction overshoot */
 			{
 				if (rankLast[1] == noOne)   /* special case, no weight 1, let's find it back at n */
 				{