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// Copyright (c) 2011 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 "net/curvecp/circular_buffer.h"
#include <algorithm>
#include "base/logging.h"
namespace net {
CircularBuffer::CircularBuffer(int capacity)
: capacity_(capacity),
head_(0),
length_(0) {
buffer_ = new char[capacity_];
}
CircularBuffer::~CircularBuffer() {
delete [] buffer_;
}
int CircularBuffer::write(const char* data, int length) {
int bytes_written = 0;
// We can't write more bytes than we have space for.
if (length > capacity_ - length_)
length = capacity_ - length_;
// Check for space at end of buffer.
if (head_ + length_ < capacity_) {
bytes_written = std::min(capacity_ - head_ - length_, length);
int end_pos = head_ + length_;
memcpy(buffer_ + end_pos, data, bytes_written);
length_ += bytes_written;
length -= bytes_written;
}
if (!length)
return bytes_written;
DCHECK_LT(length_, capacity_); // Buffer still has space.
DCHECK_GE(head_ + length_, capacity_); // Space is at the beginning.
int start_pos = (head_ + length_) % capacity_;
memcpy(&buffer_[start_pos], &data[bytes_written], length);
bytes_written += length;
length_ += length;
return bytes_written;
}
int CircularBuffer::read(char* data, int length) {
int bytes_read = 0;
// We can't read more bytes than are in the buffer.
if (length > length_)
length = length_;
while (length) {
DCHECK_LE(length, length_);
int span_end = std::min(capacity_, head_ + length);
int len = span_end - head_;
DCHECK_LE(len, length_);
memcpy(&data[bytes_read], &buffer_[head_], len);
bytes_read += len;
length -= len;
length_ -= len;
head_ += len;
DCHECK_LE(head_, capacity_);
if (head_ == capacity_)
head_ = 0;
}
return bytes_read;
}
} // namespace net
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