YPixel subtract bias to match C code

BUG=392
TESTED=TestGreyYUV
R=harryjin@google.com

Review URL: https://webrtc-codereview.appspot.com/37799004

git-svn-id: http://libyuv.googlecode.com/svn/trunk@1253 16f28f9a-4ce2-e073-06de-1de4eb20be90

README.chromium

 Name: libyuv
 URL: http://code.google.com/p/libyuv/
-Version: 1252
+Version: 1253
 License: BSD
 License File: LICENSE
 

include/libyuv/version.h

@@ -11,6 +11,6 @@
 #ifndef INCLUDE_LIBYUV_VERSION_H_  // NOLINT
 #define INCLUDE_LIBYUV_VERSION_H_
 
-#define LIBYUV_VERSION 1252
+#define LIBYUV_VERSION 1253
 
 #endif  // INCLUDE_LIBYUV_VERSION_H_  NOLINT

source/row_common.cc

@@ -988,9 +988,9 @@ static __inline void YuvPixel(uint8 y, uint8 u, uint8 v,
 // C reference code that mimics the YUV assembly.
 static __inline void YPixel(uint8 y, uint8* b, uint8* g, uint8* r) {
   uint32 y1 = (uint32)(y * 0x0101 * YG) >> 16;
-  *b = Clamp((int32)(-YGB + y1) >> 6);
-  *g = Clamp((int32)(-YGB + y1) >> 6);
-  *r = Clamp((int32)(-YGB + y1) >> 6);
+  *b = Clamp((int32)(y1 - YGB) >> 6);
+  *g = Clamp((int32)(y1 - YGB) >> 6);
+  *r = Clamp((int32)(y1 - YGB) >> 6);
 }
 
 #undef YG

unit_test/color_test.cc

@@ -21,7 +21,8 @@
 
 namespace libyuv {
 
-#ifdef _MSC_VER
+#if defined (_M_X64) || defined(_M_IX86) || \
+    defined(__x86_64__) || defined(__i386__))
 #define HIGH_ACCURACY 1
 #endif