Add SSE optimizations to AudioRendererMixer.

media/base/audio_renderer_mixer.h

 // Copyright (c) 2012 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_BASE_AUDIO_RENDERER_MIXER_H_
 #define MEDIA_BASE_AUDIO_RENDERER_MIXER_H_
 
 #include <set>
 #include <vector>
 
+#include "base/gtest_prod_util.h"
 #include "base/synchronization/lock.h"
 #include "media/base/audio_renderer_mixer_input.h"
 #include "media/base/audio_renderer_sink.h"
 #include "media/base/multi_channel_resampler.h"
 
 namespace media {
 
 // Mixes a set of AudioRendererMixerInputs into a single output stream which is
 // funneled into a single shared AudioRendererSink; saving a bundle on renderer
 // side resources.  Resampling is done post-mixing as it is the most expensive
 // process.  If the input sample rate matches the audio hardware sample rate, no
 // resampling is done.
 class MEDIA_EXPORT AudioRendererMixer
     : NON_EXPORTED_BASE(public AudioRendererSink::RenderCallback) {
  public:
   AudioRendererMixer(const AudioParameters& input_params,
                      const AudioParameters& output_params,
                      const scoped_refptr<AudioRendererSink>& sink);
   virtual ~AudioRendererMixer();
 
   // Add or remove a mixer input from mixing; called by AudioRendererMixerInput.
   void AddMixerInput(const scoped_refptr<AudioRendererMixerInput>& input);
   void RemoveMixerInput(const scoped_refptr<AudioRendererMixerInput>& input);
 
  private:
+  FRIEND_TEST_ALL_PREFIXES(AudioRendererMixerTest, VectorFMAC);
+  FRIEND_TEST_ALL_PREFIXES(AudioRendererMixerTest, VectorFMACBenchmark);
+
   // AudioRendererSink::RenderCallback implementation.
   virtual int Render(const std::vector<float*>& audio_data,
                      int number_of_frames,
                      int audio_delay_milliseconds) OVERRIDE;
   virtual void OnRenderError() OVERRIDE;
 
   // Handles mixing and volume adjustment.  Renders |number_of_frames| into
   // |audio_data|.  When resampling is necessary, ProvideInput() will be called
   // by MultiChannelResampler when more data is necessary.
   void ProvideInput(const std::vector<float*>& audio_data,
                     int number_of_frames);
 
+  // Multiply each element of |src| (up to |len|) by |scale| and add to |dest|.
+  static void VectorFMAC(const float src[], float scale, int len, float dest[]);
+  static void VectorFMAC_C(const float src[], float scale, int len,
+                           float dest[]);
+  // SSE optimized VectorFMAC, requires |src|, |dest| to be 16-byte aligned.
+  static void VectorFMAC_SSE(const float src[], float scale, int len,
+                             float dest[]);
+
   // Output sink for this mixer.
   scoped_refptr<AudioRendererSink> audio_sink_;
 
   // Set of mixer inputs to be mixed by this mixer.  Access is thread-safe
   // through |mixer_inputs_lock_|.
   typedef std::set< scoped_refptr<AudioRendererMixerInput> >
       AudioRendererMixerInputSet;
   AudioRendererMixerInputSet mixer_inputs_;
   base::Lock mixer_inputs_lock_;
 
   // Vector for rendering audio data from each mixer input.
   int mixer_input_audio_data_size_;
   std::vector<float*> mixer_input_audio_data_;
 
   // Handles resampling post-mixing.
   scoped_ptr<MultiChannelResampler> resampler_;
 
   // The audio delay in milliseconds received by the last Render() call.
   int current_audio_delay_milliseconds_;
 
   DISALLOW_COPY_AND_ASSIGN(AudioRendererMixer);
 };
 
 }  // namespace media
 
 #endif  // MEDIA_BASE_AUDIO_RENDERER_MIXER_H_