mirror of
https://github.com/libretro/scummvm.git
synced 2024-12-26 19:55:44 +00:00
326 lines
8.7 KiB
C++
326 lines
8.7 KiB
C++
/* 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 2
|
|
* 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, write to the Free Software
|
|
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
|
|
*
|
|
*/
|
|
|
|
// Based on eos' BitStream implementation
|
|
|
|
#ifndef COMMON_BITSTREAM_H
|
|
#define COMMON_BITSTREAM_H
|
|
|
|
#include "common/scummsys.h"
|
|
#include "common/textconsole.h"
|
|
#include "common/stream.h"
|
|
|
|
namespace Common {
|
|
|
|
/** A bit stream. */
|
|
class BitStream {
|
|
public:
|
|
virtual ~BitStream() {
|
|
}
|
|
|
|
/** Return the stream position in bits. */
|
|
virtual uint32 pos() const = 0;
|
|
|
|
/** Return the stream size in bits. */
|
|
virtual uint32 size() const = 0;
|
|
|
|
/** Has the end of the stream been reached? */
|
|
virtual bool eos() const = 0;
|
|
|
|
/** Rewind the bit stream back to the start. */
|
|
virtual void rewind() = 0;
|
|
|
|
/** Skip the specified amount of bits. */
|
|
virtual void skip(uint32 n) = 0;
|
|
|
|
/** Read a bit from the bit stream. */
|
|
virtual uint32 getBit() = 0;
|
|
|
|
/** Read a multi-bit value from the bit stream. */
|
|
virtual uint32 getBits(uint8 n) = 0;
|
|
|
|
/** Read a bit from the bit stream, without changing the stream's position. */
|
|
virtual uint32 peekBit() = 0;
|
|
|
|
/** Read a multi-bit value from the bit stream, without changing the stream's position. */
|
|
virtual uint32 peekBits(uint8 n) = 0;
|
|
|
|
/** Add a bit to the value x, making it an n+1-bit value. */
|
|
virtual void addBit(uint32 &x, uint32 n) = 0;
|
|
|
|
protected:
|
|
BitStream() {
|
|
}
|
|
};
|
|
|
|
/**
|
|
* 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 32bit little-endian values
|
|
* from the data stream and hands out the bits in the order of LSB to MSB.
|
|
*/
|
|
template<int valueBits, bool isLE, bool isMSB2LSB>
|
|
class BitStreamImpl : public BitStream {
|
|
private:
|
|
SeekableReadStream *_stream; ///< The input stream.
|
|
bool _disposeAfterUse; ///< Should we delete the stream on destruction?
|
|
|
|
uint32 _value; ///< Current value.
|
|
uint8 _inValue; ///< Position within the current value.
|
|
|
|
/** Read a data value. */
|
|
inline 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;
|
|
}
|
|
|
|
/** Read the next data value. */
|
|
inline void readValue() {
|
|
if ((size() - pos()) < valueBits)
|
|
error("BitStreamImpl::readValue(): End of bit stream reached");
|
|
|
|
_value = readData();
|
|
if (_stream->err() || _stream->eos())
|
|
error("BitStreamImpl::readValue(): Read error");
|
|
|
|
// If we're reading the bits MSB first, we need to shift the value to that position
|
|
if (isMSB2LSB)
|
|
_value <<= 32 - valueBits;
|
|
}
|
|
|
|
public:
|
|
/** Create a bit stream using this input data stream and optionally delete it on destruction. */
|
|
BitStreamImpl(SeekableReadStream *stream, bool disposeAfterUse = false) :
|
|
_stream(stream), _disposeAfterUse(disposeAfterUse), _value(0), _inValue(0) {
|
|
|
|
if ((valueBits != 8) && (valueBits != 16) && (valueBits != 32))
|
|
error("BitStreamImpl: Invalid memory layout %d, %d, %d", valueBits, isLE, isMSB2LSB);
|
|
}
|
|
|
|
/** Create a bit stream using this input data stream. */
|
|
BitStreamImpl(SeekableReadStream &stream) :
|
|
_stream(&stream), _disposeAfterUse(false), _value(0), _inValue(0) {
|
|
|
|
if ((valueBits != 8) && (valueBits != 16) && (valueBits != 32))
|
|
error("BitStreamImpl: Invalid memory layout %d, %d, %d", valueBits, isLE, isMSB2LSB);
|
|
}
|
|
|
|
~BitStreamImpl() {
|
|
if (_disposeAfterUse)
|
|
delete _stream;
|
|
}
|
|
|
|
/** Read a bit from the bit stream. */
|
|
uint32 getBit() {
|
|
// Check if we need the next value
|
|
if (_inValue == 0)
|
|
readValue();
|
|
|
|
// Get the current bit
|
|
int b = 0;
|
|
if (isMSB2LSB)
|
|
b = ((_value & 0x80000000) == 0) ? 0 : 1;
|
|
else
|
|
b = ((_value & 1) == 0) ? 0 : 1;
|
|
|
|
// Shift to the next bit
|
|
if (isMSB2LSB)
|
|
_value <<= 1;
|
|
else
|
|
_value >>= 1;
|
|
|
|
// Increase the position within the current value
|
|
_inValue = (_inValue + 1) % valueBits;
|
|
|
|
return b;
|
|
}
|
|
|
|
/**
|
|
* Read a multi-bit value from the bit stream.
|
|
*
|
|
* The value is read as if just taken as a whole from the bitstream.
|
|
*
|
|
* For example:
|
|
* Reading a 4-bit value from an 8-bit bitstream with the contents 01010011:
|
|
* If the bitstream is MSB2LSB, the 4-bit value would be 0101.
|
|
* If the bitstream is LSB2MSB, the 4-bit value would be 0011.
|
|
*/
|
|
uint32 getBits(uint8 n) {
|
|
if (n == 0)
|
|
return 0;
|
|
|
|
if (n > 32)
|
|
error("BitStreamImpl::getBits(): Too many bits requested to be read");
|
|
|
|
// Read the number of bits
|
|
uint32 v = 0;
|
|
|
|
if (isMSB2LSB) {
|
|
while (n-- > 0)
|
|
v = (v << 1) | getBit();
|
|
} else {
|
|
for (uint32 i = 0; i < n; i++)
|
|
v = (v >> 1) | (((uint32) getBit()) << 31);
|
|
|
|
v >>= (32 - n);
|
|
}
|
|
|
|
return v;
|
|
}
|
|
|
|
/** Read a bit from the bit stream, without changing the stream's position. */
|
|
uint32 peekBit() {
|
|
uint32 value = _value;
|
|
uint8 inValue = _inValue;
|
|
uint32 curPos = _stream->pos();
|
|
|
|
uint32 v = getBit();
|
|
|
|
_stream->seek(curPos);
|
|
_inValue = inValue;
|
|
_value = value;
|
|
|
|
return v;
|
|
}
|
|
|
|
/**
|
|
* Read a multi-bit value from the bit stream, without changing the stream's position.
|
|
*
|
|
* The bit order is the same as in getBits().
|
|
*/
|
|
uint32 peekBits(uint8 n) {
|
|
uint32 value = _value;
|
|
uint8 inValue = _inValue;
|
|
uint32 curPos = _stream->pos();
|
|
|
|
uint32 v = getBits(n);
|
|
|
|
_stream->seek(curPos);
|
|
_inValue = inValue;
|
|
_value = value;
|
|
|
|
return v;
|
|
}
|
|
|
|
/**
|
|
* 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, dependant on the stream's bitorder.
|
|
*
|
|
* For example:
|
|
* A bit y is added to the value 00001100 with size 4.
|
|
* If the stream's bitorder is MSB2LSB, the resulting value is 0001100y.
|
|
* If the stream's bitorder 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 (isMSB2LSB)
|
|
x = (x << 1) | getBit();
|
|
else
|
|
x = (x & ~(1 << n)) | (getBit() << n);
|
|
}
|
|
|
|
/** Rewind the bit stream back to the start. */
|
|
void rewind() {
|
|
_stream->seek(0);
|
|
|
|
_value = 0;
|
|
_inValue = 0;
|
|
}
|
|
|
|
/** Skip the specified amount of bits. */
|
|
void skip(uint32 n) {
|
|
while (n-- > 0)
|
|
getBit();
|
|
}
|
|
|
|
/** Return the stream position in bits. */
|
|
uint32 pos() const {
|
|
if (_stream->pos() == 0)
|
|
return 0;
|
|
|
|
uint32 p = (_inValue == 0) ? _stream->pos() : ((_stream->pos() - 1) & ~((uint32) ((valueBits >> 3) - 1)));
|
|
return p * 8 + _inValue;
|
|
}
|
|
|
|
/** Return the stream size in bits. */
|
|
uint32 size() const {
|
|
return (_stream->size() & ~((uint32) ((valueBits >> 3) - 1))) * 8;
|
|
}
|
|
|
|
bool eos() const {
|
|
return _stream->eos() || (pos() >= size());
|
|
}
|
|
};
|
|
|
|
// typedefs for various memory layouts.
|
|
|
|
/** 8-bit data, MSB to LSB. */
|
|
typedef BitStreamImpl<8, false, true > BitStream8MSB;
|
|
/** 8-bit data, LSB to MSB. */
|
|
typedef BitStreamImpl<8, false, false> BitStream8LSB;
|
|
|
|
/** 16-bit little-endian data, MSB to LSB. */
|
|
typedef BitStreamImpl<16, true , true > BitStream16LEMSB;
|
|
/** 16-bit little-endian data, LSB to MSB. */
|
|
typedef BitStreamImpl<16, true , false> BitStream16LELSB;
|
|
/** 16-bit big-endian data, MSB to LSB. */
|
|
typedef BitStreamImpl<16, false, true > BitStream16BEMSB;
|
|
/** 16-bit big-endian data, LSB to MSB. */
|
|
typedef BitStreamImpl<16, false, false> BitStream16BELSB;
|
|
|
|
/** 32-bit little-endian data, MSB to LSB. */
|
|
typedef BitStreamImpl<32, true , true > BitStream32LEMSB;
|
|
/** 32-bit little-endian data, LSB to MSB. */
|
|
typedef BitStreamImpl<32, true , false> BitStream32LELSB;
|
|
/** 32-bit big-endian data, MSB to LSB. */
|
|
typedef BitStreamImpl<32, false, true > BitStream32BEMSB;
|
|
/** 32-bit big-endian data, LSB to MSB. */
|
|
typedef BitStreamImpl<32, false, false> BitStream32BELSB;
|
|
|
|
} // End of namespace Common
|
|
|
|
#endif // COMMON_BITSTREAM_H
|