From fb5d659bbd90b1bc2af3b1485968fa4b6cdce2ba Mon Sep 17 00:00:00 2001
From: Pascal Massimino <pascal.massimino@gmail.com>
Date: Thu, 14 Jul 2011 22:06:24 -0700
Subject: [PATCH] fix an overflow bug in LUT calculation

round(clip()) != clip(round())

Change-Id: Ia53f845b62e01bce672456cb7cdf8581f1a7ce44
---
 src/dec/yuv.c | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/src/dec/yuv.c b/src/dec/yuv.c
index 82ca9982..2b203f7b 100644
--- a/src/dec/yuv.c
+++ b/src/dec/yuv.c
@@ -24,6 +24,10 @@ uint8_t VP8kClip4Bits[YUV_RANGE_MAX - YUV_RANGE_MIN];
 
 static int done = 0;
 
+static inline uint8_t clip(int v, int max_value) {
+  return v < 0 ? 0 : v > max_value ? max_value : v;
+}
+
 void VP8YUVInit(void) {
   int i;
   if (done) {
@@ -37,8 +41,8 @@ void VP8YUVInit(void) {
   }
   for (i = YUV_RANGE_MIN; i < YUV_RANGE_MAX; ++i) {
     const int k = ((i - 16) * 76283 + YUV_HALF) >> YUV_FIX;
-    VP8kClip[i - YUV_RANGE_MIN] = (k < 0) ? 0 : (k > 255) ? 255 : k;
-    VP8kClip4Bits[i - YUV_RANGE_MIN] = (VP8kClip[i - YUV_RANGE_MIN] + 8) >> 4;
+    VP8kClip[i - YUV_RANGE_MIN] = clip(k, 255);
+    VP8kClip4Bits[i - YUV_RANGE_MIN] = clip((k + 8) >> 4, 15);
   }
   done = 1;
 }