Update audio code to use size_t more correctly, webrtc/common_audio/ portion.

webrtc/common_audio/blocker.cc

 /*
  *  Copyright (c) 2014 The WebRTC project authors. All Rights Reserved.
  *
  *  Use of this source code is governed by a BSD-style license
  *  that can be found in the LICENSE file in the root of the source
  *  tree. An additional intellectual property rights grant can be found
  *  in the file PATENTS.  All contributing project authors may
  *  be found in the AUTHORS file in the root of the source tree.
  */
 
 #include "webrtc/common_audio/blocker.h"
 
 #include <string.h>
 
 #include "webrtc/base/checks.h"
 
 namespace {
 
 // Adds |a| and |b| frame by frame into |result| (basically matrix addition).
 void AddFrames(const float* const* a,
-               int a_start_index,
+               size_t a_start_index,
                const float* const* b,
                int b_start_index,
-               int num_frames,
+               size_t num_frames,
                int num_channels,
                float* const* result,
-               int result_start_index) {
+               size_t result_start_index) {
   for (int i = 0; i < num_channels; ++i) {
-    for (int j = 0; j < num_frames; ++j) {
+    for (size_t j = 0; j < num_frames; ++j) {
       result[i][j + result_start_index] =
           a[i][j + a_start_index] + b[i][j + b_start_index];
     }
   }
 }
 
 // Copies |src| into |dst| channel by channel.
 void CopyFrames(const float* const* src,
-                int src_start_index,
-                int num_frames,
+                size_t src_start_index,
+                size_t num_frames,
                 int num_channels,
                 float* const* dst,
-                int dst_start_index) {
+                size_t dst_start_index) {
   for (int i = 0; i < num_channels; ++i) {
     memcpy(&dst[i][dst_start_index],
            &src[i][src_start_index],
            num_frames * sizeof(dst[i][dst_start_index]));
   }
 }
 
 // Moves |src| into |dst| channel by channel.
 void MoveFrames(const float* const* src,
-                int src_start_index,
-                int num_frames,
+                size_t src_start_index,
+                size_t num_frames,
                 int num_channels,
                 float* const* dst,
-                int dst_start_index) {
+                size_t dst_start_index) {
   for (int i = 0; i < num_channels; ++i) {
     memmove(&dst[i][dst_start_index],
             &src[i][src_start_index],
             num_frames * sizeof(dst[i][dst_start_index]));
   }
 }
 
 void ZeroOut(float* const* buffer,
-             int starting_idx,
-             int num_frames,
+             size_t starting_idx,
+             size_t num_frames,
              int num_channels) {
   for (int i = 0; i < num_channels; ++i) {
     memset(&buffer[i][starting_idx], 0,
            num_frames * sizeof(buffer[i][starting_idx]));
   }
 }
 
 // Pointwise multiplies each channel of |frames| with |window|. Results are
 // stored in |frames|.
 void ApplyWindow(const float* window,
-                 int num_frames,
+                 size_t num_frames,
                  int num_channels,
                  float* const* frames) {
   for (int i = 0; i < num_channels; ++i) {
-    for (int j = 0; j < num_frames; ++j) {
+    for (size_t j = 0; j < num_frames; ++j) {
       frames[i][j] = frames[i][j] * window[j];
     }
   }
 }
 
-int gcd(int a, int b) {
-  int tmp;
+size_t gcd(size_t a, size_t b) {
+  size_t tmp;
   while (b) {
      tmp = a;
      a = b;
      b = tmp % b;
   }
   return a;
 }
 
 }  // namespace
 
 namespace webrtc {
 
-Blocker::Blocker(int chunk_size,
-                 int block_size,
+Blocker::Blocker(size_t chunk_size,
+                 size_t block_size,
                  int num_input_channels,
                  int num_output_channels,
                  const float* window,
-                 int shift_amount,
+                 size_t shift_amount,
                  BlockerCallback* callback)
     : chunk_size_(chunk_size),
       block_size_(block_size),
       num_input_channels_(num_input_channels),
       num_output_channels_(num_output_channels),
       initial_delay_(block_size_ - gcd(chunk_size, shift_amount)),
       frame_offset_(0),
       input_buffer_(num_input_channels_, chunk_size_ + initial_delay_),
       output_buffer_(chunk_size_ + initial_delay_, num_output_channels_),
       input_block_(block_size_, num_input_channels_),
       output_block_(block_size_, num_output_channels_),
       window_(new float[block_size_]),
       shift_amount_(shift_amount),
       callback_(callback) {
   CHECK_LE(num_output_channels_, num_input_channels_);
   CHECK(window);
 
   memcpy(window_.get(), window, block_size_ * sizeof(*window_.get()));
-  input_buffer_.MoveReadPosition(-initial_delay_);
+  input_buffer_.MoveReadPosition(-static_cast<int>(initial_delay_));

[Peter Kasting, 2015/07/23 00:26:47]

A couple places we call MoveReadPosition() with a (possibly-)negative value we
compute from one or more size_ts.  Rather than casting, another option would be
to split MoveReadPosition() into two functions:

  void MoveReadPositionForward(size_t bytes);
  void MoveReadPositionBackward(size_t bytes);

This would avoid the need for casts.  I'm not sure whether it's worth doing;
feel free to opine.

[Andrew MacDonald, 2015/07/24 19:01:55]

I think that makes a lot of sense. CL up here:
https://codereview.webrtc.org/1252943007/

I looked at similarly modifying the underlying C code, but the echo canceller
depends on it rather subtly. New code will all be in C++, so I think it's fair
to restrict the change to the wrapper.

[Peter Kasting, 2015/07/27 23:23:38]

I will update once you land this.

 }
 
 // When block_size < chunk_size the input and output buffers look like this:
 //
 //                      delay*             chunk_size    chunk_size + delay*
 //  buffer: <-------------|---------------------|---------------|>
 //                _a_              _b_                 _c_
 //
 // On each call to ProcessChunk():
 // 1. New input gets read into sections _b_ and _c_ of the input buffer.
@@ skipping 22 matching lines @@
 // 5. We copy section _a_ of the output buffer into output.
 // 6. For both the input and the output buffers, we copy sections _b_ and _c_
 //    into section _a_ and _b_.
 // 7. We set the new frame_offset to be the difference between the first frame
 //    of |bl| and the border between sections _a_ and _b_.
 //
 // * delay here refers to inintial_delay_
 //
 // TODO(claguna): Look at using ring buffers to eliminate some copies.
 void Blocker::ProcessChunk(const float* const* input,
-                           int chunk_size,
+                           size_t chunk_size,
                            int num_input_channels,
                            int num_output_channels,
                            float* const* output) {
   CHECK_EQ(chunk_size, chunk_size_);
   CHECK_EQ(num_input_channels, num_input_channels_);
   CHECK_EQ(num_output_channels, num_output_channels_);
 
   input_buffer_.Write(input, num_input_channels, chunk_size_);
-  int first_frame_in_block = frame_offset_;
+  size_t first_frame_in_block = frame_offset_;
 
   // Loop through blocks.
   while (first_frame_in_block < chunk_size_) {
     input_buffer_.Read(input_block_.channels(), num_input_channels,
                        block_size_);
-    input_buffer_.MoveReadPosition(-block_size_ + shift_amount_);
+    input_buffer_.MoveReadPosition(
+        -static_cast<int>(block_size_) + static_cast<int>(shift_amount_));
 
     ApplyWindow(window_.get(),
                 block_size_,
                 num_input_channels_,
                 input_block_.channels());
     callback_->ProcessBlock(input_block_.channels(),
                             block_size_,
                             num_input_channels_,
                             num_output_channels_,
                             output_block_.channels());
@@ skipping 33 matching lines @@
   ZeroOut(output_buffer_.channels(),
           initial_delay_,
           chunk_size_,
           num_output_channels_);
 
   // Calculate new starting frames.
   frame_offset_ = first_frame_in_block - chunk_size_;
 }
 
 }  // namespace webrtc