mirror of
https://github.com/libretro/scummvm.git
synced 2024-12-03 23:52:41 +00:00
115 lines
4.6 KiB
C++
115 lines
4.6 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.
|
|
*
|
|
*/
|
|
|
|
#ifndef CINE_UNPACK_H
|
|
#define CINE_UNPACK_H
|
|
|
|
|
|
#include "common/scummsys.h"
|
|
|
|
namespace Cine {
|
|
|
|
/**
|
|
* A LZ77 style decompressor for Delphine's data files
|
|
* used in at least Future Wars and Operation Stealth.
|
|
* @note Works backwards in the source and destination buffers.
|
|
* @warning Having the source and destination in the same buffer when unpacking can cause errors!
|
|
*/
|
|
class CineUnpacker {
|
|
public:
|
|
/**
|
|
* Unpacks packed data from the source buffer to the destination buffer.
|
|
* @note You may call this on already unpacked data but then source length must be equal to destination length.
|
|
* @warning The source and destination should not point to the same buffer. If they do, errors may occur!
|
|
* @param src Pointer to the source buffer.
|
|
* @param srcLen Length of the source buffer.
|
|
* @param dst Pointer to the destination buffer.
|
|
* @param dstLen Length of the destination buffer.
|
|
* @return True if no errors were detected in the source data and unpacking was successful, otherwise false.
|
|
*/
|
|
bool unpack(const byte *src, uint srcLen, byte *dst, uint dstLen);
|
|
private:
|
|
/**
|
|
* Reads an unsigned big endian 32-bit integer from the source stream and goes backwards 4 bytes.
|
|
* @return If the operation is valid, an unsigned big endian 32-bit integer read from the source stream.
|
|
* @return If the operation is invalid, zero.
|
|
* @note Sets internal error state if the read operation would be out of source bounds.
|
|
*/
|
|
uint32 readSource();
|
|
|
|
/**
|
|
* Shifts the current internal 32-bit chunk to the right by one.
|
|
* Puts input carry into internal chunk's topmost (i.e. leftmost) bit.
|
|
* @return The least significant bit that was shifted out from the chunk.
|
|
*/
|
|
uint rcr(bool inputCarry);
|
|
|
|
/**
|
|
* Get the next bit from the source stream.
|
|
* @note Changes the bit position in the source stream.
|
|
* @return The next bit from the source stream.
|
|
*/
|
|
uint nextBit();
|
|
|
|
/**
|
|
* Get bits from the source stream.
|
|
* @note Changes the bit position in the source stream.
|
|
* @param numBits Number of bits to read from the source stream.
|
|
* @return Integer value consisting of the bits read from the source stream (In range [0, (2 ** numBits) - 1]).
|
|
* @return Later the bit was read from the source, the less significant it is in the return value.
|
|
*/
|
|
uint getBits(uint numBits);
|
|
|
|
/**
|
|
* Copy raw bytes from the input stream and write them to the destination stream.
|
|
* This is used when no adequately long match is found in the sliding window.
|
|
* @note Sets internal error state if the operation would be out of bounds.
|
|
* @param numBytes Amount of bytes to copy from the input stream
|
|
*/
|
|
void unpackRawBytes(uint numBytes);
|
|
|
|
/**
|
|
* Copy bytes from the sliding window in the destination buffer.
|
|
* This is used when a match of two bytes or longer is found.
|
|
* @note Sets internal error state if the operation would be out of bounds.
|
|
* @param offset Offset in the sliding window
|
|
* @param numBytes Amount of bytes to copy
|
|
*/
|
|
void copyRelocatedBytes(uint offset, uint numBytes);
|
|
private:
|
|
uint32 _crc; ///< Error-detecting code (This should be zero after successful unpacking)
|
|
uint32 _chunk32b; ///< The current internal 32-bit chunk of source data
|
|
byte *_dst; ///< Pointer to the current position in the destination buffer
|
|
const byte *_src; ///< Pointer to the current position in the source buffer
|
|
|
|
// These are used for detecting errors (e.g. out of bounds issues) during unpacking
|
|
bool _error; ///< Did an error occur during unpacking?
|
|
const byte *_srcBegin; ///< Source buffer's beginning
|
|
const byte *_srcEnd; ///< Source buffer's end
|
|
byte *_dstBegin; ///< Destination buffer's beginning
|
|
byte *_dstEnd; ///< Destination buffer's end
|
|
};
|
|
|
|
} // End of namespace Cine
|
|
|
|
#endif
|