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/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
#include "mp4_demuxer/BitReader.h"
#include <media/stagefright/foundation/ABitReader.h>
using namespace mozilla;
using namespace stagefright;
namespace mp4_demuxer
{
BitReader::BitReader(const mozilla::MediaByteBuffer* aBuffer)
: mBitReader(new ABitReader(aBuffer->Elements(), aBuffer->Length()))
, mSize(aBuffer->Length()) {}
BitReader::BitReader(const uint8_t* aBuffer, size_t aLength)
: mBitReader(new ABitReader(aBuffer, aLength))
, mSize(aLength) {}
BitReader::~BitReader() {}
uint32_t
BitReader::ReadBits(size_t aNum)
{
MOZ_ASSERT(aNum <= 32);
if (mBitReader->numBitsLeft() < aNum) {
return 0;
}
return mBitReader->getBits(aNum);
}
// Read unsigned integer Exp-Golomb-coded.
uint32_t
BitReader::ReadUE()
{
uint32_t i = 0;
while (ReadBit() == 0 && i < 32) {
i++;
}
if (i == 32) {
// This can happen if the data is invalid, or if it's
// short, since ReadBit() will return 0 when it runs
// off the end of the buffer.
NS_WARNING("Invalid H.264 data");
return 0;
}
uint32_t r = ReadBits(i);
r += (1 << i) - 1;
return r;
}
// Read signed integer Exp-Golomb-coded.
int32_t
BitReader::ReadSE()
{
int32_t r = ReadUE();
if (r & 1) {
return (r+1) / 2;
} else {
return -r / 2;
}
}
uint64_t
BitReader::ReadU64()
{
uint64_t hi = ReadU32();
uint32_t lo = ReadU32();
return (hi << 32) | lo;
}
uint64_t
BitReader::ReadUTF8()
{
int64_t val = ReadBits(8);
uint32_t top = (val & 0x80) >> 1;
if ((val & 0xc0) == 0x80 || val >= 0xFE) {
// error.
return -1;
}
while (val & top) {
int tmp = ReadBits(8) - 128;
if (tmp >> 6) {
// error.
return -1;
}
val = (val << 6) + tmp;
top <<= 5;
}
val &= (top << 1) - 1;
return val;
}
size_t
BitReader::BitCount() const
{
return mSize * 8 - mBitReader->numBitsLeft();
}
} // namespace mp4_demuxer
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