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/* ScummVM - Graphic Adventure Engine
*
* ScummVM is the legal property of its developers, whose names
* are too numerous to list here. Please refer to the COPYRIGHT
* file distributed with this source distribution.
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*
*/
// Based on xoreos' BitStream implementation
#ifndef COMMON_BITSTREAM_H
#define COMMON_BITSTREAM_H
#include "common/scummsys.h"
#include "common/textconsole.h"
#include "common/stream.h"
#include "common/types.h"
#include "common/util.h"
namespace Common {
/**
* @defgroup common_bitstream Bit stream
* @ingroup common
*
* @brief API for implementing a bit stream.
*
* @{
*/
/**
* A template implementing a bit stream for different data memory layouts.
*
* Such a bit stream reads valueBits-wide values from the data stream and
* gives access to their bits, one at a time.
*
* For example, a bit stream with the layout parameters 32, true, false
* for valueBits, isLE and isMSB2LSB, reads 32-bit little-endian values
* from the data stream and hands out the bits in the order of LSB to MSB.
*/
template<class STREAM, typename CONTAINER, int valueBits, bool isLE, bool MSB2LSB>
class BitStreamImpl {
private:
STREAM *_stream; //!< The input stream.
DisposeAfterUse::Flag _disposeAfterUse; //!< Whether to delete the stream on destruction.
CONTAINER _bitContainer; //!< The currently available bits.
uint8 _bitsLeft; //!< Number of bits currently left in the bit container.
uint32 _size; //!< Total bit stream size (in bits).
uint32 _pos; //!< Current bit stream position (in bits).
/** Read a data value. */
FORCEINLINE uint32 readData() {
if (isLE) {
if (valueBits == 8)
return _stream->readByte();
if (valueBits == 16)
return _stream->readUint16LE();
if (valueBits == 32)
return _stream->readUint32LE();
} else {
if (valueBits == 8)
return _stream->readByte();
if (valueBits == 16)
return _stream->readUint16BE();
if (valueBits == 32)
return _stream->readUint32BE();
}
assert(false);
return 0;
}
/** Fill the container with at least @p min bits. */
FORCEINLINE void fillContainer(size_t min) {
while (_bitsLeft < min) {
CONTAINER data;
if (_pos + _bitsLeft + valueBits <= _size) {
data = readData();
} else {
// Peeking data out of bounds is well-defined and returns 0 bits.
// This is for convenience when using speed-up techniques reading
// more bits than actually available. Call eos() to check if data
// was actually read out of bounds. Peeking out of bounds does not
// set the eos flag.
data = 0;
}
// Move the data value to the right position in the bit container
if (MSB2LSB)
_bitContainer |= data << ((sizeof(_bitContainer) * 8) - valueBits - _bitsLeft);
else
_bitContainer |= data << _bitsLeft;
_bitsLeft += valueBits;
}
}
/** Get @p n bits from the bit container. */
FORCEINLINE static uint32 getNBits(CONTAINER value, size_t n) {
if (n == 0)
return 0;
const size_t toShift = (sizeof(value) * 8) - n;
if (MSB2LSB)
return value >> toShift;
else
return (value << toShift) >> toShift;
}
/** Skip already read bits. */
FORCEINLINE void skipBits(size_t n) {
assert(n <= _bitsLeft);
// Shift to the next bit
if (MSB2LSB)
_bitContainer <<= n;
else
_bitContainer >>= n;
_bitsLeft -= n;
_pos += n;
}
public:
/** Create a bit stream using this input data stream and optionally delete it on destruction. */
BitStreamImpl(STREAM *stream, DisposeAfterUse::Flag disposeAfterUse = DisposeAfterUse::NO) :
_stream(stream), _disposeAfterUse(disposeAfterUse), _bitContainer(0), _bitsLeft(0), _pos(0) {
if ((valueBits != 8) && (valueBits != 16) && (valueBits != 32))
error("BitStreamImpl: Invalid memory layout %d, %d, %d", valueBits, int(isLE), int(MSB2LSB));
_size = (_stream->size() & ~((uint32) ((valueBits >> 3) - 1))) * 8;
}
/** Create a bit stream using this input data stream. */
BitStreamImpl(STREAM &stream) :
_stream(&stream), _disposeAfterUse(DisposeAfterUse::NO), _bitContainer(0), _bitsLeft(0), _pos(0) {
if ((valueBits != 8) && (valueBits != 16) && (valueBits != 32))
error("BitStreamImpl: Invalid memory layout %d, %d, %d", valueBits, int(isLE), int(MSB2LSB));
_size = (_stream->size() & ~((uint32) ((valueBits >> 3) - 1))) * 8;
}
~BitStreamImpl() {
if (_disposeAfterUse == DisposeAfterUse::YES)
delete _stream;
}
/** Read a bit from the bit stream, without changing the stream's position. */
uint peekBit() {
fillContainer(1);
return getNBits(_bitContainer, 1);
}
/** Read a bit from the bit stream. */
uint getBit() {
const uint b = peekBit();
skipBits(1);
return b;
}
/**
* Read a multi-bit value from the bit stream, without changing the stream's position.
*
* The bit order is the same as in @ref getBits().
*/
template<int n>
uint32 peekBits() {
if (n > 32)
error("BitStreamImpl::peekBits(): Too many bits requested to be peeked");
fillContainer(n);
return getNBits(_bitContainer, n);
}
/**
* Read a multi-bit value from the bit stream.
*
* The value is read as if just taken as a whole from the bit stream.
*
* For example:
* Reading a 4-bit value from an 8-bit bit stream with the contents 01010011:
* If the bit stream is MSB2LSB, the 4-bit value would be 0101.
* If the bit stream is LSB2MSB, the 4-bit value would be 0011.
*/
template<int n>
uint32 getBits() {
if (n > 32)
error("BitStreamImpl::getBits(): Too many bits requested to be read");
const uint32 b = peekBits<n>();
skipBits(n);
return b;
}
/**
* Read a multi-bit value from the bit stream, without changing the stream's position.
*
* The bit order is the same as in @ref getBits().
*/
uint32 peekBits(size_t n) {
if (n > 32)
error("BitStreamImpl::peekBits(): Too many bits requested to be peeked");
fillContainer(n);
return getNBits(_bitContainer, n);
}
/**
* Read a multi-bit value from the bit stream.
*
* The value is read as if just taken as a whole from the bit stream.
*
* For example:
* Reading a 4-bit value from an 8-bit bit stream with the contents 01010011:
* If the bit stream is MSB2LSB, the 4-bit value would be 0101.
* If the bit stream is LSB2MSB, the 4-bit value would be 0011.
*/
uint32 getBits(size_t n) {
if (n > 32)
error("BitStreamImpl::getBits(): Too many bits requested to be read");
const uint32 b = peekBits(n);
skipBits(n);
return b;
}
/**
* Add a bit to the value x, making it an n+1-bit value.
*
* The current value is shifted and the bit is added to the
* appropriate place, depending on the stream's bit order.
*
* For example:
* A bit y is added to the value 00001100 with size 4.
* If the stream's bit order is MSB2LSB, the resulting value is 0001100y.
* If the stream's bit order is LSB2MSB, the resulting value is 000y1100.
*/
void addBit(uint32 &x, uint32 n) {
if (n >= 32)
error("BitStreamImpl::addBit(): Too many bits requested to be read");
if (MSB2LSB)
x = (x << 1) | getBit();
else
x = (x & ~(1 << n)) | (getBit() << n);
}
/** Rewind the bit stream back to the start. */
void rewind() {
_stream->seek(0);
_bitContainer = 0;
_bitsLeft = 0;
_pos = 0;
}
/** Skip the specified number of bits. */
void skip(uint32 n) {
if (n >= _bitsLeft) {
n -= _bitsLeft;
skipBits(_bitsLeft);
}
while (n > 32) {
fillContainer(32);
skipBits(32);
n -= 32;
}
fillContainer(n);
skipBits(n);
}
/** Skip the bits to closest data value border. */
void align() {
uint32 bitsAfterBoundary = _pos % valueBits;
if (bitsAfterBoundary) {
skip(valueBits - bitsAfterBoundary);
}
}
/** Return the stream position in bits. */
uint32 pos() const {
return _pos;
}
/** Return the stream size in bits. */
uint32 size() const {
return _size;
}
bool eos() const {
return _stream->eos() || (_pos >= _size);
}
static bool isMSB2LSB() {
return MSB2LSB;
}
};
/**
* A cut-down version of MemoryReadStream specifically for use with BitStream.
* It removes the virtual call overhead for reading bytes from a memory buffer,
* and allows directly inlining this access.
*
* FIXME:
* The code duplication with MemoryReadStream is not ideal.
* It might be possible to avoid this by making this a final subclass of
* MemoryReadStream. Deviating from it would also allow faster aligned memory
* loads.
*/
class BitStreamMemoryStream {
private:
const byte * const _ptrOrig;
const byte *_ptr;
const uint32 _size;
uint32 _pos;
DisposeAfterUse::Flag _disposeMemory;
bool _eos;
/** @overload */
public:
BitStreamMemoryStream(const byte *dataPtr, uint32 dataSize, DisposeAfterUse::Flag disposeMemory = DisposeAfterUse::NO) :
_ptrOrig(dataPtr),
_ptr(dataPtr),
_size(dataSize),
_pos(0),
_disposeMemory(disposeMemory),
_eos(false) {}
~BitStreamMemoryStream() {
if (_disposeMemory)
free(const_cast<byte *>(_ptrOrig));
}
bool eos() const {
return _eos;
}
bool err() const {
return false;
}
uint32 pos() const {
return _pos;
}
uint32 size() const {
return _size;
}
bool seek(uint32 offset) {
assert(offset <= _size);
_eos = false;
_pos = offset;
_ptr = _ptrOrig + _pos;
return true;
}
byte readByte() {
if (_pos >= _size) {
_eos = true;
return 0;
}
_pos++;
return *_ptr++;
}
uint16 readUint16LE() {
if (_pos + 2 > _size) {
_eos = true;
if (_pos < _size) {
_pos++;
return *_ptr++;
} else {
return 0;
}
}
uint16 val = READ_LE_UINT16(_ptr);
_pos += 2;
_ptr += 2;
return val;
}
uint16 readUint16BE() {
if (_pos + 2 > _size) {
_eos = true;
if (_pos < _size) {
_pos++;
return (*_ptr++) << 8;
} else {
return 0;
}
}
uint16 val = READ_LE_UINT16(_ptr);
_pos += 2;
_ptr += 2;
return val;
}
uint32 readUint32LE() {
if (_pos + 4 > _size) {
uint32 val = readByte();
val |= (uint32)readByte() << 8;
val |= (uint32)readByte() << 16;
val |= (uint32)readByte() << 24;
return val;
}
uint32 val = READ_LE_UINT32(_ptr);
_pos += 4;
_ptr += 4;
return val;
}
uint32 readUint32BE() {
if (_pos + 4 > _size) {
uint32 val = (uint32)readByte() << 24;
val |= (uint32)readByte() << 16;
val |= (uint32)readByte() << 8;
val |= (uint32)readByte();
return val;
}
uint32 val = READ_BE_UINT32(_ptr);
_pos += 4;
_ptr += 4;
return val;
}
};
/**
* @name Typedefs for various memory layouts
* @{
*/
/** 8-bit data, MSB to LSB. */
typedef BitStreamImpl<SeekableReadStream, uint64, 8, false, true > BitStream8MSB;
/** 8-bit data, LSB to MSB. */
typedef BitStreamImpl<SeekableReadStream, uint64, 8, false, false> BitStream8LSB;
/** 16-bit little-endian data, MSB to LSB. */
typedef BitStreamImpl<SeekableReadStream, uint64, 16, true , true > BitStream16LEMSB;
/** 16-bit little-endian data, LSB to MSB. */
typedef BitStreamImpl<SeekableReadStream, uint64, 16, true , false> BitStream16LELSB;
/** 16-bit big-endian data, MSB to LSB. */
typedef BitStreamImpl<SeekableReadStream, uint64, 16, false, true > BitStream16BEMSB;
/** 16-bit big-endian data, LSB to MSB. */
typedef BitStreamImpl<SeekableReadStream, uint64, 16, false, false> BitStream16BELSB;
/** 32-bit little-endian data, MSB to LSB. */
typedef BitStreamImpl<SeekableReadStream, uint64, 32, true , true > BitStream32LEMSB;
/** 32-bit little-endian data, LSB to MSB. */
typedef BitStreamImpl<SeekableReadStream, uint64, 32, true , false> BitStream32LELSB;
/** 32-bit big-endian data, MSB to LSB. */
typedef BitStreamImpl<SeekableReadStream, uint64, 32, false, true > BitStream32BEMSB;
/** 32-bit big-endian data, LSB to MSB. */
typedef BitStreamImpl<SeekableReadStream, uint64, 32, false, false> BitStream32BELSB;
/** 8-bit data, MSB to LSB. */
typedef BitStreamImpl<BitStreamMemoryStream, uint64, 8, false, true > BitStreamMemory8MSB;
/** 8-bit data, LSB to MSB. */
typedef BitStreamImpl<BitStreamMemoryStream, uint64, 8, false, false> BitStreamMemory8LSB;
/** 16-bit little-endian data, MSB to LSB. */
typedef BitStreamImpl<BitStreamMemoryStream, uint64, 16, true , true > BitStreamMemory16LEMSB;
/** 16-bit little-endian data, LSB to MSB. */
typedef BitStreamImpl<BitStreamMemoryStream, uint64, 16, true , false> BitStreamMemory16LELSB;
/** 16-bit big-endian data, MSB to LSB. */
typedef BitStreamImpl<BitStreamMemoryStream, uint64, 16, false, true > BitStreamMemory16BEMSB;
/** 16-bit big-endian data, LSB to MSB. */
typedef BitStreamImpl<BitStreamMemoryStream, uint64, 16, false, false> BitStreamMemory16BELSB;
/** 32-bit little-endian data, MSB to LSB. */
typedef BitStreamImpl<BitStreamMemoryStream, uint64, 32, true , true > BitStreamMemory32LEMSB;
/** 32-bit little-endian data, LSB to MSB. */
typedef BitStreamImpl<BitStreamMemoryStream, uint64, 32, true , false> BitStreamMemory32LELSB;
/** 32-bit big-endian data, MSB to LSB. */
typedef BitStreamImpl<BitStreamMemoryStream, uint64, 32, false, true > BitStreamMemory32BEMSB;
/** 32-bit big-endian data, LSB to MSB. */
typedef BitStreamImpl<BitStreamMemoryStream, uint64, 32, false, false> BitStreamMemory32BELSB;
/** @} */
/** @} */
} // End of namespace Common
#endif // COMMON_BITSTREAM_H