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      1 /*
      2  * Copyright (C) 2011 The Android Open Source Project
      3  *
      4  * Licensed under the Apache License, Version 2.0 (the "License");
      5  * you may not use this file except in compliance with the License.
      6  * You may obtain a copy of the License at
      7  *
      8  *      http://www.apache.org/licenses/LICENSE-2.0
      9  *
     10  * Unless required by applicable law or agreed to in writing, software
     11  * distributed under the License is distributed on an "AS IS" BASIS,
     12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
     13  * See the License for the specific language governing permissions and
     14  * limitations under the License.
     15  */
     16 
     17 #include "ring_buffer.h"
     18 
     19 #include "integral_types.h"
     20 
     21 namespace video_editing {
     22 
     23 void RingBuffer::Init(int size, int num_channels, int num_readers) {
     24   size_ = size;
     25   num_channels_ = num_channels;
     26   num_readers_ = num_readers;
     27   temp_read_buffer_size_ = 1024;
     28   initialized_ = true;
     29   Reset();
     30 }
     31 
     32 RingBuffer::RingBuffer()
     33     : initialized_(false), samples_(NULL),
     34       num_readers_(0), temp_read_buffer_(NULL) {
     35 }
     36 
     37 RingBuffer::~RingBuffer() {
     38   delete[] samples_;
     39   delete[] temp_read_buffer_;
     40 }
     41 
     42 void RingBuffer::Reset() {
     43   delete[] samples_;
     44   samples_ = new float[size_ * num_channels_];
     45   memset(samples_, 0,
     46          size_ * num_channels_ * sizeof(samples_[0]));
     47 
     48   temp_read_buffer_size_ = 1024;
     49   delete[] temp_read_buffer_;
     50   temp_read_buffer_ = new float[temp_read_buffer_size_ * num_channels_];
     51   memset(temp_read_buffer_, 0,
     52          temp_read_buffer_size_ * num_channels_ * sizeof(samples_[0]));
     53   readers_.clear();
     54   for (int i = 0; i < num_readers_; ++i) {
     55     readers_.push_back(0LL);
     56   }
     57   head_logical_ = 0LL;
     58   head_ = 0;
     59 }
     60 
     61 int RingBuffer::available(int reader) const {
     62   return head_logical_ - readers_[reader];
     63 }
     64 
     65 int RingBuffer::overhead() const {
     66   int64 tail = GetTail();
     67   return tail + size_ - head_logical_;
     68 }
     69 
     70 int64 RingBuffer::GetTail() const {
     71   return *min_element(readers_.begin(), readers_.end());
     72 }
     73 
     74 int64 RingBuffer::Tell(int reader) const {
     75   return readers_[reader];
     76 }
     77 
     78 void RingBuffer::Seek(int reader, int64 position) {
     79   readers_[reader] = position;
     80 }
     81 
     82 void RingBuffer::Write(const float* samples, int num_frames) {
     83   if (!num_frames) {
     84     return;
     85   }
     86   if (head_ + num_frames <= size_) {
     87     memcpy(samples_ + head_ * num_channels_, samples,
     88            num_frames * num_channels_ * sizeof(samples[0]));
     89     head_ += num_frames;
     90   } else {
     91     int overhead = size_ - head_;
     92     memcpy(samples_ + head_ * num_channels_, samples,
     93            num_channels_ * overhead * sizeof(samples[0]));
     94     head_ = num_frames - overhead;
     95     memcpy(samples_, samples + overhead * num_channels_,
     96            num_channels_ * head_ * sizeof(samples[0]));
     97   }
     98   head_logical_ += num_frames;
     99 }
    100 
    101 void RingBuffer::Copy(int reader, float* destination, int num_frames) const {
    102   int pos = Tell(reader) % size_;
    103   if (pos + num_frames <= size_) {
    104     memcpy(destination, samples_ + pos * num_channels_,
    105            num_channels_ * num_frames * sizeof(destination[0]));
    106   } else {
    107     int wrapped = size_ - pos;
    108     memcpy(destination, samples_ + pos * num_channels_,
    109            num_channels_ * wrapped * sizeof(destination[0]));
    110     int remaining = num_frames - wrapped;
    111     memcpy(destination + wrapped * num_channels_, samples_,
    112            num_channels_ * remaining * sizeof(destination[0]));
    113   }
    114 }
    115 
    116 float* RingBuffer::GetPointer(int reader, int num_frames) {
    117   int pos = Tell(reader) % size_;
    118   if (pos + num_frames <= size_) {
    119     return samples_ + pos * num_channels_;
    120   } else {
    121     if (num_frames > temp_read_buffer_size_) {
    122       temp_read_buffer_size_ = num_frames;
    123       delete[] temp_read_buffer_;
    124       temp_read_buffer_ =
    125           new float[temp_read_buffer_size_ * num_channels_];  // NOLINT
    126     }
    127     Copy(reader, temp_read_buffer_, num_frames);
    128     return temp_read_buffer_;
    129   }
    130 }
    131 
    132 void RingBuffer::MergeBack(int reader, const float* source, int num_frames) {
    133   // If the source pointer is not the temporary buffer,
    134   // data updates were performed in place, so there is nothing to do.
    135   // Otherwise, copy samples from the temp buffer back to the ring buffer.
    136   if (source == temp_read_buffer_) {
    137     int pos = Tell(reader) % size_;
    138     if (pos + num_frames <= size_) {
    139       memcpy(samples_ + (pos * num_channels_), source,
    140              num_channels_ * num_frames * sizeof(source[0]));
    141     } else {
    142       int wrapped = size_ - pos;
    143       memcpy(samples_ + (pos * num_channels_), source,
    144              num_channels_ * wrapped * sizeof(source[0]));
    145       int remaining = num_frames - wrapped;
    146       memcpy(samples_, source + (wrapped * num_channels_),
    147              num_channels_ * remaining * sizeof(source[0]));
    148     }
    149   }
    150 }
    151 
    152 }  // namespace video_editing
    153