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- // Copyright 2013 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.
- #include "components/webrtc_logging/common/partial_circular_buffer.h"
- #include <algorithm>
- #include <cstring>
- #include "base/check_op.h"
- namespace webrtc_logging {
- PartialCircularBuffer::PartialCircularBuffer(void* buffer, uint32_t buffer_size)
- : buffer_data_(reinterpret_cast<BufferData*>(buffer)),
- memory_buffer_size_(buffer_size),
- data_size_(0),
- position_(0),
- total_read_(0) {
- uint32_t header_size =
- buffer_data_->data - reinterpret_cast<uint8_t*>(buffer_data_.get());
- data_size_ = memory_buffer_size_ - header_size;
- DCHECK(buffer_data_);
- DCHECK_GE(memory_buffer_size_, header_size);
- DCHECK_LE(buffer_data_->total_written, data_size_);
- DCHECK_LT(buffer_data_->wrap_position, data_size_);
- DCHECK_LT(buffer_data_->end_position, data_size_);
- }
- PartialCircularBuffer::PartialCircularBuffer(void* buffer,
- uint32_t buffer_size,
- uint32_t wrap_position,
- bool append)
- : buffer_data_(reinterpret_cast<BufferData*>(buffer)),
- memory_buffer_size_(buffer_size),
- data_size_(0),
- position_(0),
- total_read_(0) {
- uint32_t header_size =
- buffer_data_->data - reinterpret_cast<uint8_t*>(buffer_data_.get());
- data_size_ = memory_buffer_size_ - header_size;
- DCHECK(buffer_data_);
- DCHECK_GE(memory_buffer_size_, header_size);
- if (append) {
- DCHECK_LT(buffer_data_->wrap_position, data_size_);
- position_ = buffer_data_->end_position;
- } else {
- DCHECK_LT(wrap_position, data_size_);
- buffer_data_->total_written = 0;
- buffer_data_->wrap_position = wrap_position;
- buffer_data_->end_position = 0;
- }
- }
- uint32_t PartialCircularBuffer::Read(void* buffer, uint32_t buffer_size) {
- DCHECK(buffer_data_);
- if (total_read_ >= buffer_data_->total_written)
- return 0;
- uint8_t* buffer_uint8 = reinterpret_cast<uint8_t*>(buffer);
- uint32_t read = 0;
- // Read from beginning part.
- if (position_ < buffer_data_->wrap_position) {
- uint32_t to_wrap_pos = buffer_data_->wrap_position - position_;
- uint32_t to_eow = buffer_data_->total_written - total_read_;
- uint32_t to_read = std::min({buffer_size, to_wrap_pos, to_eow});
- memcpy(buffer_uint8, buffer_data_->data + position_, to_read);
- position_ += to_read;
- total_read_ += to_read;
- read += to_read;
- if (position_ == buffer_data_->wrap_position &&
- buffer_data_->total_written == data_size_) {
- // We've read all the beginning part, set the position to the middle part.
- // (The second condition above checks if the wrapping part is filled, i.e.
- // writing has wrapped.)
- position_ = buffer_data_->end_position;
- }
- if (read >= buffer_size) {
- DCHECK_EQ(read, buffer_size);
- return read;
- }
- if (read >= to_eow) {
- DCHECK_EQ(read, to_eow);
- DCHECK_EQ(total_read_, buffer_data_->total_written);
- return read;
- }
- }
- // Read from middle part.
- DCHECK_GE(position_, buffer_data_->wrap_position);
- if (position_ >= buffer_data_->end_position) {
- uint32_t remaining_buffer_size = buffer_size - read;
- uint32_t to_eof = data_size_ - position_;
- uint32_t to_eow = buffer_data_->total_written - total_read_;
- uint32_t to_read = std::min({remaining_buffer_size, to_eof, to_eow});
- memcpy(buffer_uint8 + read, buffer_data_->data + position_, to_read);
- position_ += to_read;
- total_read_ += to_read;
- read += to_read;
- if (position_ == data_size_) {
- // We've read all the middle part, set position to the end part.
- position_ = buffer_data_->wrap_position;
- }
- if (read >= buffer_size) {
- DCHECK_EQ(read, buffer_size);
- return read;
- }
- if (total_read_ >= buffer_data_->total_written) {
- DCHECK_EQ(total_read_, buffer_data_->total_written);
- return read;
- }
- }
- // Read from end part.
- DCHECK_GE(position_, buffer_data_->wrap_position);
- DCHECK_LT(position_, buffer_data_->end_position);
- uint32_t remaining_buffer_size = buffer_size - read;
- uint32_t to_eob = buffer_data_->end_position - position_;
- uint32_t to_eow = buffer_data_->total_written - total_read_;
- uint32_t to_read = std::min({remaining_buffer_size, to_eob, to_eow});
- memcpy(buffer_uint8 + read, buffer_data_->data + position_, to_read);
- position_ += to_read;
- total_read_ += to_read;
- read += to_read;
- DCHECK_LE(read, buffer_size);
- DCHECK_LE(total_read_, buffer_data_->total_written);
- return read;
- }
- void PartialCircularBuffer::Write(const void* buffer, uint32_t buffer_size) {
- DCHECK(buffer_data_);
- const uint8_t* input = static_cast<const uint8_t*>(buffer);
- uint32_t wrap_position = buffer_data_->wrap_position;
- uint32_t cycle_size = data_size_ - wrap_position;
- // First write the non-wrapping part.
- if (position_ < wrap_position) {
- uint32_t space_left = wrap_position - position_;
- uint32_t write_size = std::min(buffer_size, space_left);
- DoWrite(input, write_size);
- input += write_size;
- buffer_size -= write_size;
- }
- // Skip the part that would overlap.
- if (buffer_size > cycle_size) {
- uint32_t skip = buffer_size - cycle_size;
- input += skip;
- buffer_size -= skip;
- position_ = wrap_position + (position_ - wrap_position + skip) % cycle_size;
- }
- // Finally write the wrapping part.
- DoWrite(input, buffer_size);
- }
- void PartialCircularBuffer::DoWrite(const uint8_t* input, uint32_t input_size) {
- DCHECK_LT(position_, data_size_);
- buffer_data_->total_written =
- std::min(buffer_data_->total_written + input_size, data_size_);
- // Write() skips any overlapping part, so this loop will run at most twice.
- while (input_size > 0) {
- uint32_t space_left = data_size_ - position_;
- uint32_t write_size = std::min(input_size, space_left);
- memcpy(buffer_data_->data + position_, input, write_size);
- input += write_size;
- input_size -= write_size;
- position_ += write_size;
- if (position_ >= data_size_) {
- DCHECK_EQ(position_, data_size_);
- position_ = buffer_data_->wrap_position;
- }
- }
- buffer_data_->end_position = position_;
- }
- } // namespace webrtc_logging
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