Split MoveReadPosition into Forward and Backward versions.

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.
  */
 
@@ skipping 101 matching lines @@
       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);
+  CHECK_LE(shift_amount_, block_size_);
 
   memcpy(window_.get(), window, block_size_ * sizeof(*window_.get()));
-  input_buffer_.MoveReadPosition(-initial_delay_);
+  input_buffer_.MoveReadPositionBackward(initial_delay_);
 }
 
 // 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 37 matching lines @@
   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_;
 
   // 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_.MoveReadPositionBackward(block_size_ - 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