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/* ScummVM - Scumm Interpreter
* Copyright (C) 2001 Ludvig Strigeus
* Copyright (C) 2001/2002 The ScummVM project
*
* 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., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
*
* $Header$
*
*/
#ifndef COMMON_STREAM_H
#define COMMON_STREAM_H
#include "stdafx.h"
#include "common/scummsys.h"
namespace Common {
class WriteStream {
public:
virtual uint32 write(const void *ptr, uint32 size) = 0;
// The remaining methods all have default implementations
void writeByte(byte value);
void writeSByte(int8 value);
void writeUint16LE(uint16 value);
void writeUint24LE(uint32 value);
void writeUint32LE(uint32 value);
void writeUint16BE(uint16 value);
void writeUint24BE(uint32 value);
void writeUint32BE(uint32 value);
void writeSint16LE(int16 value);
void writeSint24LE(int32 value);
void writeSint32LE(int32 value);
void writeSint16BE(int16 value);
void writeSint24BE(int32 value);
void writeSint32BE(int32 value);
};
class ReadStream {
public:
virtual uint32 read(void *ptr, uint32 size) = 0;
// The remaining methods all have default implementations
byte readByte();
int8 readSByte();
uint16 readUint16LE();
uint32 readUint24LE();
uint32 readUint32LE();
uint16 readUint16BE();
uint32 readUint24BE();
uint32 readUint32BE();
int16 readSint16LE();
int32 readSint24LE();
int32 readSint32LE();
int16 readSint16BE();
int32 readSint24BE();
int32 readSint32BE();
};
/**
* XORReadStream is a wrapper around an arbitrary other ReadStream,
* which 'decrypts' the data being read by XORing all data bytes with the given
* encryption 'key'.
*
* Currently, this is not used anywhere, it's just a demo of how one can chain
* streams if necessary.
*/
class XORReadStream : public ReadStream {
private:
byte _encbyte;
ReadStream *_realStream;
public:
XORReadStream(ReadStream *in = 0, byte enc = 0) : _realStream(in), _encbyte(enc) {}
void setStream(ReadStream *in) { _realStream = in; }
void setEnc(byte value) { _encbyte = value; }
uint32 read(void *ptr, uint32 size) {
assert(_realStream);
uint32 len = _realStream->read(ptr, size);
if (_encbyte) {
byte *p = (byte *)ptr;
byte *end = p + len;
while (p < end)
*p++ ^= _encbyte;
}
return len;
}
};
/**
* Simple memory based 'stream', which implements the ReadStream interface for
* a plain memory block.
*/
class MemoryReadStream : public ReadStream {
private:
const byte *_ptr;
const byte * const _ptrOrig;
const uint32 _bufSize;
uint32 _pos;
public:
MemoryReadStream(const byte *buf, uint32 len) : _ptr(buf), _ptrOrig(buf), _bufSize(len), _pos(0) {}
uint32 read(void *ptr, uint32 len) {
// Read at most as many bytes as are still available...
if (len > _bufSize - _pos)
len = _bufSize - _pos;
memcpy(ptr, _ptr, len);
_ptr += len;
_pos += len;
return len;
}
bool eof() { return _pos == _bufSize; }
uint32 pos() { return _pos; }
uint32 size() { return _bufSize; }
void seek(uint32 offs, int whence = SEEK_SET) {
// Pre-Condition
assert(_pos <= _bufSize);
switch (whence) {
case SEEK_END:
// SEEK_END works just like SEEK_SET, only 'reversed',
// i.e. from the end.
offs = _bufSize - offs;
// Fall through
case SEEK_SET:
_ptr = _ptrOrig + offs;
_pos = offs;
break;
case SEEK_CUR:
_ptr += offs;
_pos += offs;
break;
}
// Post-Condition
assert(_pos <= _bufSize);
}
};
} // End of namespace Common
#endif
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