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// Copyright (c) 2012 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 "media/base/bit_reader.h"
namespace media {
BitReader::BitReader()
: data_(NULL),
bytes_left_(0),
position_(0),
curr_byte_(0),
num_remaining_bits_in_curr_byte_(0) {
}
BitReader::BitReader(const uint8* data, off_t size) {
Initialize(data, size);
}
BitReader::~BitReader() {}
void BitReader::Initialize(const uint8* data, off_t size) {
DCHECK(data != NULL || size == 0); // Data cannot be NULL if size is not 0.
data_ = data;
bytes_left_ = size;
position_ = 0;
num_remaining_bits_in_curr_byte_ = 0;
UpdateCurrByte();
}
void BitReader::UpdateCurrByte() {
DCHECK_EQ(num_remaining_bits_in_curr_byte_, 0);
if (bytes_left_ < 1)
return;
// Load a new byte and advance pointers.
curr_byte_ = *data_;
++data_;
--bytes_left_;
num_remaining_bits_in_curr_byte_ = 8;
}
bool BitReader::SkipBits(int num_bits) {
int dummy;
const int kDummySize = static_cast<int>(sizeof(dummy)) * 8;
while (num_bits > kDummySize) {
if (ReadBits(kDummySize, &dummy)) {
num_bits -= kDummySize;
} else {
return false;
}
}
return ReadBits(num_bits, &dummy);
}
off_t BitReader::Tell() const {
return position_;
}
off_t BitReader::NumBitsLeft() const {
return (num_remaining_bits_in_curr_byte_ + bytes_left_ * 8);
}
bool BitReader::HasMoreData() const {
return num_remaining_bits_in_curr_byte_ != 0;
}
} // namespace media
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