Move HalfFloatMaker to media

media/video/half_float_maker_xor.h

+// Copyright 2017 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef MEDIA_VIDEO_HALF_FLOAT_MAKER_XOR_H_
+#define MEDIA_VIDEO_HALF_FLOAT_MAKER_XOR_H_
+
+#include "media/base/media_export.h"
+#include "media/video/half_float_maker.h"
+
+namespace media {
+// 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 MEDIA_EXPORT HalfFloatMaker_xor : public media::HalfFloatMaker {

[hubbe, 2017/03/22 17:48:22]

I don't think you need to expose this class in a header file.
Just put it in half_float_maker.c and have a factory function for
constructing an HalfFloatMaker which decides between the xor and libyuv version.

[Uzair, 2017/03/23 07:13:30]

Done.

+ public:
+  explicit HalfFloatMaker_xor(int bits_per_channel);
+  float Offset() const override;
+  float Multiplier() const override;
+  void MakeHalfFloats(const uint16_t* src, size_t num, uint16_t* dst) override;
+
+ private:
+  int bits_per_channel_;
+};
+
+}  // namespace media
+#endif  // MEDIA_VIDEO_HALF_FLOAT_MAKER_H_