Split DelayNode processing into a-rate and k-rate functions

This CL jsut splits the processing for a DelayNode into separate
routines to handle a-rate and k-rate processing.

This is a first step at vectorizing delay node.

No functional changes.

Bug: 1087071
Change-Id: Ia12bad0748e608eb4e20bd86b07b7bd4f1e54c2a
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2227335Reviewed-by: Hongchan Choi <hongchan@chromium.org>
Commit-Queue: Raymond Toy <rtoy@chromium.org>
Cr-Commit-Position: refs/heads/master@{#775129}

third_party/blink/renderer/platform/audio/audio_delay_dsp_kernel.cc

@@ -81,7 +81,7 @@ double AudioDelayDSPKernel::DelayTime(float sample_rate) {
   return desired_delay_frames_ / sample_rate;
 }
 
-void AudioDelayDSPKernel::Process(const float* source,
+void AudioDelayDSPKernel::ProcessARate(const float* source,
                                        float* destination,
                                        uint32_t frames_to_process) {
   int buffer_length = buffer_.size();
@@ -96,7 +96,6 @@ void AudioDelayDSPKernel::Process(const float* source,
   float sample_rate = this->SampleRate();
   double max_time = MaxDelayTime();
 
-  if (HasSampleAccurateValues() && IsAudioRate()) {
   float* delay_times = delay_times_.Data();
   CalculateSampleAccurateValues(delay_times, frames_to_process);
 
@@ -139,7 +138,23 @@ void AudioDelayDSPKernel::Process(const float* source,
   }
 
   write_index_ = w_index;
-  } else {
+}
+
+void AudioDelayDSPKernel::ProcessKRate(const float* source,
+                                       float* destination,
+                                       uint32_t frames_to_process) {
+  int buffer_length = buffer_.size();
+  float* buffer = buffer_.Data();
+
+  DCHECK(buffer_length);
+  DCHECK(source);
+  DCHECK(destination);
+  DCHECK_GE(write_index_, 0);
+  DCHECK_LT(write_index_, buffer_length);
+
+  float sample_rate = this->SampleRate();
+  double max_time = MaxDelayTime();
+
   // This is basically the same as above, but optimized for the case where the
   // delay time is constant for the current render.
   //
@@ -192,6 +207,15 @@ void AudioDelayDSPKernel::Process(const float* source,
   }
 
   write_index_ = w - buffer;
+}
+
+void AudioDelayDSPKernel::Process(const float* source,
+                                  float* destination,
+                                  uint32_t frames_to_process) {
+  if (HasSampleAccurateValues() && IsAudioRate()) {
+    ProcessARate(source, destination, frames_to_process);
+  } else {
+    ProcessKRate(source, destination, frames_to_process);
   }
 }
 

third_party/blink/renderer/platform/audio/audio_delay_dsp_kernel.h

@@ -35,9 +35,22 @@ class PLATFORM_EXPORT AudioDelayDSPKernel : public AudioDSPKernel {
  public:
   AudioDelayDSPKernel(double max_delay_time, float sample_rate);
 
+  // Process the delay.  Basically dispatches to either ProcessKRate or
+  // ProcessARate.
   void Process(const float* source,
                float* destination,
                uint32_t frames_to_process) override;
+
+  // Handles k-rate processing
+  void ProcessKRate(const float* source,
+                    float* destination,
+                    uint32_t frames_to_process);
+
+  // Handles a-rate processing
+  void ProcessARate(const float* source,
+                    float* destination,
+                    uint32_t frames_to_process);
+
   void Reset() override;
 
   float MaxDelayTime() const { return max_delay_time_; }