Move HalfFloatMaker to media

cc/resources/video_resource_updater.cc

Index: cc/resources/video_resource_updater.cc
diff --git a/cc/resources/video_resource_updater.cc b/cc/resources/video_resource_updater.cc
index 2ad91ae0674558bb9ad7f5963aa68c50d6554c38..fa01b03ad49ad1accbbd3ab44f8d0f2e6ff266e3 100644
--- a/cc/resources/video_resource_updater.cc
+++ b/cc/resources/video_resource_updater.cc
@@ -21,6 +21,7 @@
 #include "gpu/command_buffer/client/gles2_interface.h"
 #include "media/base/video_frame.h"
 #include "media/renderers/skcanvas_video_renderer.h"
+#include "media/video/half_float_maker.h"
 #include "third_party/khronos/GLES2/gl2.h"
 #include "third_party/khronos/GLES2/gl2ext.h"
 #include "third_party/libyuv/include/libyuv.h"
@@ -298,89 +299,6 @@ static gfx::Size SoftwarePlaneDimension(media::VideoFrame* input_frame,
   return gfx::Size(plane_width, plane_height);
 }
 
-namespace {
-// By OR-ing with 0x3800, 10-bit numbers become half-floats in the
-// range [0.5..1) and 9-bit numbers get the range [0.5..0.75).
-//
-// Half-floats are evaluated as:
-// float value = pow(2.0, exponent - 25) * (0x400 + fraction);
-//
-// In our case the exponent is 14 (since we or with 0x3800) and
-// pow(2.0, 14-25) * 0x400 evaluates to 0.5 (our offset) and
-// pow(2.0, 14-25) * fraction is [0..0.49951171875] for 10-bit and
-// [0..0.24951171875] for 9-bit.
-//
-// https://en.wikipedia.org/wiki/Half-precision_floating-point_format
-class HalfFloatMaker_xor : public VideoResourceUpdater::HalfFloatMaker {
- public:
-  explicit HalfFloatMaker_xor(int bits_per_channel)
-      : bits_per_channel_(bits_per_channel) {}
-  float Offset() const override { return 0.5; }
-  float Multiplier() const override {
-    int max_input_value = (1 << bits_per_channel_) - 1;
-    // 2 << 11 = 2048 would be 1.0 with our exponent.
-    return 2048.0 / max_input_value;
-  }
-  void MakeHalfFloats(const uint16_t* src, size_t num, uint16_t* dst) override {
-    // Micro-benchmarking indicates that the compiler does
-    // a good enough job of optimizing this loop that trying
-    // to manually operate on one uint64 at a time is not
-    // actually helpful.
-    // Note to future optimizers: Benchmark your optimizations!
-    for (size_t i = 0; i < num; i++)
-      dst[i] = src[i] | 0x3800;
-  }
-
- private:
-  int bits_per_channel_;
-};
-
-class HalfFloatMaker_libyuv : public VideoResourceUpdater::HalfFloatMaker {
- public:
-  explicit HalfFloatMaker_libyuv(int bits_per_channel) {
-    int max_value = (1 << bits_per_channel) - 1;
-    // For less than 15 bits, we can give libyuv a multiplier of
-    // 1.0, which is faster on some platforms. If bits is 16 or larger,
-    // a multiplier of 1.0 would cause overflows. However, a multiplier
-    // of 1/max_value would cause subnormal floats, which perform
-    // very poorly on some platforms.
-    if (bits_per_channel <= 15) {
-      libyuv_multiplier_ = 1.0f;
-    } else {
-      // This multiplier makes sure that we avoid subnormal values.
-      libyuv_multiplier_ = 1.0f / 4096.0f;
-    }
-    resource_multiplier_ = 1.0f / libyuv_multiplier_ / max_value;
-  }
-  float Offset() const override { return 0.0f; }
-  float Multiplier() const override { return resource_multiplier_; }
-  void MakeHalfFloats(const uint16_t* src, size_t num, uint16_t* dst) override {
-    // Source and dest stride can be zero since we're only copying
-    // one row at a time.
-    int stride = 0;
-    int rows = 1;
-    libyuv::HalfFloatPlane(src, stride, dst, stride, libyuv_multiplier_, num,
-                           rows);
-  }
-
- private:
-  float libyuv_multiplier_;
-  float resource_multiplier_;
-};
-
-}  // namespace
-
-std::unique_ptr<VideoResourceUpdater::HalfFloatMaker>
-VideoResourceUpdater::NewHalfFloatMaker(int bits_per_channel) {
-  if (bits_per_channel < 11) {
-    return std::unique_ptr<VideoResourceUpdater::HalfFloatMaker>(
-        new HalfFloatMaker_xor(bits_per_channel));
-  } else {
-    return std::unique_ptr<VideoResourceUpdater::HalfFloatMaker>(
-        new HalfFloatMaker_libyuv(bits_per_channel));
-  }
-}
-
 VideoFrameExternalResources VideoResourceUpdater::CreateForSoftwarePlanes(
     scoped_refptr<media::VideoFrame> video_frame) {
   TRACE_EVENT0("cc", "VideoResourceUpdater::CreateForSoftwarePlanes");
@@ -518,10 +436,11 @@ VideoFrameExternalResources VideoResourceUpdater::CreateForSoftwarePlanes(
     return external_resources;
   }
 
-  std::unique_ptr<HalfFloatMaker> half_float_maker;
+  std::unique_ptr<media::HalfFloatMaker> half_float_maker;
   if (resource_provider_->YuvResourceFormat(bits_per_channel) ==
       LUMINANCE_F16) {
-    half_float_maker = NewHalfFloatMaker(bits_per_channel);
+    half_float_maker =
+        media::HalfFloatMaker::NewHalfFloatMaker(bits_per_channel);
     external_resources.offset = half_float_maker->Offset();
     external_resources.multiplier = half_float_maker->Multiplier();
   }
@@ -533,7 +452,7 @@ VideoFrameExternalResources VideoResourceUpdater::CreateForSoftwarePlanes(
               resource_provider_->YuvResourceFormat(bits_per_channel));
 
     if (!plane_resource.Matches(video_frame->unique_id(), i)) {
-      // TODO(hubbe): Move all conversion (and upload?) code to media/.
+      // TODO(hubbe): Move upload code to media/.
       // We need to transfer data from |video_frame| to the plane resource.
       // TODO(reveman): Can use GpuMemoryBuffers here to improve performance.