Add rounding to FixedDiv

BUG=250
TEST=unittest more exact
R=dingkai@google.com, ryanpetrie@google.com

Review URL: https://webrtc-codereview.appspot.com/1681005

git-svn-id: http://libyuv.googlecode.com/svn/trunk@735 16f28f9a-4ce2-e073-06de-1de4eb20be90

README.chromium

 Name: libyuv
 URL: http://code.google.com/p/libyuv/
-Version: 734
+Version: 735
 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 734
+#define LIBYUV_VERSION 735
 
 #endif  // INCLUDE_LIBYUV_VERSION_H_  NOLINT

source/row_common.cc

@@ -757,7 +757,8 @@ extern const uint32 kRecipTable[4097] = {
 // Divide num by div and return as 16.16 fixed point result.
 int FixedDiv_C(int num, int div) {
   if (static_cast<unsigned int>(div) <= 4097u) {
-    return static_cast<int>((static_cast<int64>(num) * kRecipTable[div]) >> 16);
+    return static_cast<int>((static_cast<int64>(num) * kRecipTable[div] +
+                             0x8000) >> 16);
   }
   return static_cast<int>((static_cast<int64>(num) << 16) / div);
 }

source/row_posix.cc

@@ -5423,6 +5423,7 @@ int FixedDiv(int num, int div) {
     "mull      (%2,%%ecx,4)                    \n"
 #endif
     "shrd      $0x10,%%edx,%%eax               \n"
+    "adc       $0,%%eax                        \n"
 
   "9:                                          \n"
     "mov       %0, %%eax                       \n"

source/row_win.cc

@@ -6616,6 +6616,7 @@ int FixedDiv(int num, int div) {
     ja         largediv
     mul        dword ptr kRecipTable[ecx * 4]
     shrd       eax, edx, 16
+    adc        eax, 0
     ret
 
   largediv:

unit_test/math_test.cc

@@ -42,10 +42,10 @@ TEST_F(libyuvTest, TestFixedDiv) {
   EXPECT_EQ(0x20000, libyuv::FixedDiv(-40000, -20000));
   EXPECT_EQ(-0x20000, libyuv::FixedDiv(40000, -20000));
   EXPECT_EQ(-0x20000, libyuv::FixedDiv(-40000, 20000));
-  EXPECT_NEAR(0x10000, libyuv::FixedDiv(4095, 4095), 1);
+  EXPECT_EQ(0x10000, libyuv::FixedDiv(4095, 4095));
   EXPECT_EQ(0x10000, libyuv::FixedDiv(4096, 4096));
   EXPECT_EQ(0x10000, libyuv::FixedDiv(4097, 4097));
-  EXPECT_NEAR(123 * 65536, libyuv::FixedDiv(123, 1), 1);
+  EXPECT_EQ(123 * 65536, libyuv::FixedDiv(123, 1));
 
   srandom(time(NULL));
   MemRandomize(reinterpret_cast<uint8*>(&num[0]), sizeof(num));