ARGBDetect do 2 pixels at a time for improved performance.

BUG=375
TESTED=libyuvTest.BenchmarkARGBDetect_Opt
R=harryjin@google.com

Review URL: https://webrtc-codereview.appspot.com/26049004

git-svn-id: http://libyuv.googlecode.com/svn/trunk@1155 16f28f9a-4ce2-e073-06de-1de4eb20be90

README.chromium

 Name: libyuv
 URL: http://code.google.com/p/libyuv/
-Version: 1152
+Version: 1155
 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 1152
+#define LIBYUV_VERSION 1155
 
 #endif  // INCLUDE_LIBYUV_VERSION_H_  NOLINT

source/compare.cc

@@ -81,14 +81,28 @@ uint32 HashDjb2(const uint8* src, uint64 count, uint32 seed) {
 
 static uint32 ARGBDetectRow_C(const uint8* argb, int width) {
   int x;
-  for (x = 0; x < width; ++x) {
+  for (x = 0; x < width - 1; x += 2) {
+    if (argb[0] != 255) {  // First byte is not Alpha of 255, so not ARGB.
+      return FOURCC_BGRA;
+    }
+    if (argb[3] != 255) {  // 4th byte is not Alpha of 255, so not BGRA.
+      return FOURCC_ARGB;
+    }
+    if (argb[4] != 255) {  // Second pixel first byte is not Alpha of 255.
+      return FOURCC_BGRA;
+    }
+    if (argb[7] != 255) {  // Second pixel 4th byte is not Alpha of 255.
+      return FOURCC_ARGB;
+    }
+    argb += 8;
+  }
+  if (width & 1) {
     if (argb[0] != 255) {  // First byte is not Alpha of 255, so not ARGB.
       return FOURCC_BGRA;
     }
     if (argb[3] != 255) {  // 4th byte is not Alpha of 255, so not BGRA.
       return FOURCC_ARGB;
     }
-    argb += 4;
   }
   return 0;
 }

unit_test/compare_test.cc

@@ -175,6 +175,33 @@ TEST_F(libyuvTest, BenchmarkARGBDetect_Opt) {
   free_aligned_buffer_64(src_a);
 }
 
+TEST_F(libyuvTest, BenchmarkARGBDetect_Unaligned) {
+  uint32 fourcc;
+  const int kMaxTest = benchmark_width_ * benchmark_height_ * 4 + 1;
+  align_buffer_64(src_a, kMaxTest);
+  for (int i = 0; i < kMaxTest; ++i) {
+    src_a[i + 1] = 255;
+  }
+
+  src_a[0 + 1] = 0;
+  fourcc = ARGBDetect(src_a + 1, benchmark_width_ * 4,
+                      benchmark_width_, benchmark_height_);
+  EXPECT_EQ(libyuv::FOURCC_BGRA, fourcc);
+  src_a[0 + 1] = 255;
+  src_a[3 + 1] = 0;
+  fourcc = ARGBDetect(src_a + 1, benchmark_width_ * 4,
+                      benchmark_width_, benchmark_height_);
+  EXPECT_EQ(libyuv::FOURCC_ARGB, fourcc);
+  src_a[3 + 1] = 255;
+
+  for (int i = 0; i < benchmark_iterations_; ++i) {
+    fourcc = ARGBDetect(src_a + 1, benchmark_width_ * 4,
+                        benchmark_width_, benchmark_height_);
+  }
+  EXPECT_EQ(0, fourcc);
+
+  free_aligned_buffer_64(src_a);
+}
 TEST_F(libyuvTest, BenchmarkSumSquareError_Opt) {
   const int kMaxWidth = 4096 * 3;
   align_buffer_64(src_a, kMaxWidth);
@@ -273,7 +300,6 @@ TEST_F(libyuvTest, BenchmarkPsnr_Opt) {
   free_aligned_buffer_64(src_b);
 }
 
-
 TEST_F(libyuvTest, BenchmarkPsnr_Unaligned) {
   align_buffer_64(src_a, benchmark_width_ * benchmark_height_ + 1);
   align_buffer_64(src_b, benchmark_width_ * benchmark_height_);