Switching to a general align function.

Review URL: https://webrtc-codereview.appspot.com/851005

git-svn-id: http://webrtc.googlecode.com/svn/trunk@2847 4adac7df-926f-26a2-2b94-8c16560cd09d

src/common_video/libyuv/include/webrtc_libyuv.h

@@ -57,11 +57,12 @@ enum VideoRotationMode {
   kRotate270 = 270,
 };
 
-// Align value to 64 bits.
+// Align integer values.
 // Input:
 //   - value     : Input value to be aligned.
-// Return value: An aligned to 64 bit form of the input value.
+//   - alignment : Alignment basis (power of 2).
-int AlignTo64Bit(int value);
+// Return value: An aligned form of the input value.
+int AlignInt(int value, int alignment);
 
 // Calculate the required buffer size.
 // Input:

src/common_video/libyuv/libyuv_unittest.cc

@@ -332,15 +332,10 @@ TEST_F(TestLibYuv, DISABLED_MirrorTest) {
 }
 
 TEST_F(TestLibYuv, alignment) {
-  int value = 640;
+  int value = 0x3FF; // 1023
-  int aligned_value = (value + 63) & ~63;
+  EXPECT_EQ(0x400, AlignInt(value, 128));  // Low 7 bits are zero.
-  EXPECT_EQ(AlignTo64Bit(value), aligned_value);
+  EXPECT_EQ(0x400, AlignInt(value, 64));  // Low 6 bits are zero.
-  value = 600;
+  EXPECT_EQ(0x400, AlignInt(value, 32));  // Low 5 bits are zero.
-  aligned_value = (value + 63) & ~63;
-  EXPECT_EQ(AlignTo64Bit(value), aligned_value);
-  value = 0;
-  aligned_value = (value + 63) & ~63;
-  EXPECT_EQ(AlignTo64Bit(value), aligned_value);
 }
 
 }  // namespace

src/common_video/libyuv/webrtc_libyuv.cc

@@ -52,8 +52,9 @@ VideoType RawVideoTypeToCommonVideoVideoType(RawVideoType type) {
   return kUnknown;
 }
 
-int AlignTo64Bit(int value) {
+int AlignInt(int value, int alignment) {
-  return ((value + 63) & ~63);
+  assert(!((alignment - 1) & alignment));
+  return ((value + alignment - 1) & ~ (alignment - 1));
 }
 
 int CalcBufferSize(VideoType type, int width, int height) {