libyuv::YUY2ToY for isolating Y channel of YUY2.

This function is the first step of YUY2 To I420.
Provided primarily for diagnostics.

TBR=wangcheng@google.com
BUG=libyuv:647
TESTED=LibYUVConvertTest.YUY2ToY_Opt

Review URL: https://codereview.chromium.org/2399153004 .

include/libyuv/planar_functions.h

@@ -111,6 +111,11 @@ int UYVYToNV12(const uint8* src_uyvy, int src_stride_uyvy,
                uint8* dst_uv, int dst_stride_uv,
                int width, int height);
 
+LIBYUV_API
+int YUY2ToY(const uint8* src_yuy2, int src_stride_yuy2,
+             uint8* dst_y, int dst_stride_y,
+             int width, int height);
+
 // Convert I420 to I400. (calls CopyPlane ignoring u/v).
 LIBYUV_API
 int I420ToI400(const uint8* src_y, int src_stride_y,

source/planar_functions.cc

@@ -588,6 +588,71 @@ int UYVYToI422(const uint8* src_uyvy, int src_stride_uyvy,
   return 0;
 }
 
+// Convert YUY2 to Y.
+LIBYUV_API
+int YUY2ToY(const uint8* src_yuy2, int src_stride_yuy2,
+             uint8* dst_y, int dst_stride_y,
+             int width, int height) {
+  int y;
+  void (*YUY2ToYRow)(const uint8* src_yuy2, uint8* dst_y, int width) =
+      YUY2ToYRow_C;
+  if (!src_yuy2 || !dst_y || width <= 0 || height == 0) {
+    return -1;
+  }
+  // Negative height means invert the image.
+  if (height < 0) {
+    height = -height;
+    src_yuy2 = src_yuy2 + (height - 1) * src_stride_yuy2;
+    src_stride_yuy2 = -src_stride_yuy2;
+  }
+  // Coalesce rows.
+  if (src_stride_yuy2 == width * 2 &&
+      dst_stride_y == width) {
+    width *= height;
+    height = 1;
+    src_stride_yuy2 = dst_stride_y = 0;
+  }
+#if defined(HAS_YUY2TOYROW_SSE2)
+  if (TestCpuFlag(kCpuHasSSE2)) {
+    YUY2ToYRow = YUY2ToYRow_Any_SSE2;
+    if (IS_ALIGNED(width, 16)) {
+      YUY2ToYRow = YUY2ToYRow_SSE2;
+    }
+  }
+#endif
+#if defined(HAS_YUY2TOYROW_AVX2)
+  if (TestCpuFlag(kCpuHasAVX2)) {
+    YUY2ToYRow = YUY2ToYRow_Any_AVX2;
+    if (IS_ALIGNED(width, 32)) {
+      YUY2ToYRow = YUY2ToYRow_AVX2;
+    }
+  }
+#endif
+#if defined(HAS_YUY2TOYROW_NEON)
+  if (TestCpuFlag(kCpuHasNEON)) {
+    YUY2ToYRow = YUY2ToYRow_Any_NEON;
+    if (IS_ALIGNED(width, 16)) {
+      YUY2ToYRow = YUY2ToYRow_NEON;
+    }
+  }
+#endif
+#if defined(HAS_YUY2TOYROW_MSA)
+  if (TestCpuFlag(kCpuHasMSA)) {
+    YUY2ToYRow = YUY2ToYRow_Any_MSA;
+    if (IS_ALIGNED(width, 32)) {
+      YUY2ToYRow = YUY2ToYRow_MSA;
+    }
+  }
+#endif
+
+  for (y = 0; y < height; ++y) {
+    YUY2ToYRow(src_yuy2, dst_y, width);
+    src_yuy2 += src_stride_yuy2;
+    dst_y += dst_stride_y;
+  }
+  return 0;
+}
+
 // Mirror I400 with optional flipping
 LIBYUV_API
 int I400Mirror(const uint8* src_y, int src_stride_y,
@@ -2699,6 +2764,7 @@ int ARGBCopyYToAlpha(const uint8* src_y, int src_stride_y,
   return 0;
 }
 
+
 // TODO(fbarchard): Consider if width is even Y channel can be split
 // directly. A SplitUVRow_Odd function could copy the remaining chroma.
 

source/row_neon.cc

@@ -10,6 +10,8 @@
 
 #include "libyuv/row.h"
 
+#include <stdio.h>
+
 #ifdef __cplusplus
 namespace libyuv {
 extern "C" {

unit_test/convert_test.cc

@@ -315,8 +315,6 @@ TEST_F(LibYUVConvertTest, SRC_FMT_PLANAR##To##FMT_PLANAR##_##PN##N) {\
 TESTAPLANARTOP(Android420, I420, 1, 0, 0, 2, 2, I420, 2, 2)
 TESTAPLANARTOP(Android420, NV12, 2, 0, 1, 2, 2, I420, 2, 2)
 TESTAPLANARTOP(Android420, NV21, 2, 1, 0, 2, 2, I420, 2, 2)
-// YUV3 causes msan failure.  skip for now.
-//TESTAPLANARTOP(Android420, YUV3, 3, 0, 1, 2, 2, I420, 2, 2)
 
 #define TESTPLANARTOBPI(SRC_FMT_PLANAR, SRC_SUBSAMP_X, SRC_SUBSAMP_Y,          \
                        FMT_PLANAR, SUBSAMP_X, SUBSAMP_Y, W1280, N, NEG, OFF)   \
@@ -1139,6 +1137,7 @@ TESTATOB(ARGB1555, 2, 2, 1, ARGB, 4, 4, 1, 0)
 TESTATOB(ARGB4444, 2, 2, 1, ARGB, 4, 4, 1, 0)
 TESTATOB(YUY2, 2, 4, 1, ARGB, 4, 4, 1, 4)
 TESTATOB(UYVY, 2, 4, 1, ARGB, 4, 4, 1, 4)
+TESTATOB(YUY2, 2, 4, 1, Y, 1, 1, 1, 0)
 TESTATOB(I400, 1, 1, 1, ARGB, 4, 4, 1, 0)
 TESTATOB(J400, 1, 1, 1, ARGB, 4, 4, 1, 0)
 TESTATOB(I400, 1, 1, 1, I400, 1, 1, 1, 0)