Move HalfFloatMaker to media

media/video/half_float_maker_xor.cc

+// Copyright (c) 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.
+
+#include "media/video/half_float_maker_xor.h"
+
+namespace media {
+
+HalfFloatMaker_xor::HalfFloatMaker_xor(int bits_per_channel)
+    : bits_per_channel_(bits_per_channel) {}
+
+float HalfFloatMaker_xor::Multiplier() const {
+  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;
+}
+
+float HalfFloatMaker_xor::Offset() const {
+  return 0.5;
+}
+
+void HalfFloatMaker_xor::MakeHalfFloats(const uint16_t* src,
+                                        size_t num,
+                                        uint16_t* dst) {
+  // 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;
+}
+
+}  // namespace media