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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 {
/**
* Generic interface for a writable data stream.
*/
class WriteStream {
public:
/**
* Write data into the stream. Subclasses must implement this
* method; all other write methods are implemented using it.
*
* @param ptr pointer to the data to be written
* @param size number of bytes to be written
* @return the number of bytes which were actually written.
*/
virtual uint32 write(const void *ptr, uint32 size) = 0;
// The remaining methods all have default implementations; subclasses
// need not (and should not) overload them.
void writeByte(byte value) {
write(&value, 1);
}
void writeSByte(int8 value) {
write(&value, 1);
}
void writeUint16LE(uint16 value) {
writeByte((byte)(value & 0xff));
writeByte((byte)(value >> 8));
}
void writeUint32LE(uint32 value) {
writeUint16LE((uint16)(value & 0xffff));
writeUint16LE((uint16)(value >> 16));
}
void writeUint16BE(uint16 value) {
writeByte((byte)(value >> 8));
writeByte((byte)(value & 0xff));
}
void writeUint32BE(uint32 value) {
writeUint16BE((uint16)(value >> 16));
writeUint16BE((uint16)(value & 0xffff));
}
void writeSint16LE(int16 value) {
writeUint16LE((uint16)value);
}
void writeSint32LE(int32 value) {
writeUint32LE((uint32)value);
}
void writeSint16BE(int16 value) {
writeUint16BE((uint16)value);
}
void writeSint32BE(int32 value) {
writeUint32BE((uint32)value);
}
};
/**
* Generic interface for a readable data stream.
*/
class ReadStream {
public:
/**
* Read data from the stream. Subclasses must implement this
* method; all other read methods are implemented using it.
*
* @param ptr pointer to a buffer into which the data is read
* @param size number of bytes to be read
* @return the number of bytes which were actually read.
*/
virtual uint32 read(void *ptr, uint32 size) = 0;
// The remaining methods all have default implementations; subclasses
// need not (and should not) overload them.
byte readByte() {
byte b = 0;
read(&b, 1);
return b;
}
int8 readSByte() {
int8 b = 0;
read(&b, 1);
return b;
}
uint16 readUint16LE() {
uint16 a = readByte();
uint16 b = readByte();
return a | (b << 8);
}
uint32 readUint32LE() {
uint32 a = readUint16LE();
uint32 b = readUint16LE();
return (b << 16) | a;
}
uint16 readUint16BE() {
uint16 b = readByte();
uint16 a = readByte();
return a | (b << 8);
}
uint32 readUint32BE() {
uint32 b = readUint16BE();
uint32 a = readUint16BE();
return (b << 16) | a;
}
int16 readSint16LE() {
return (int16)readUint16LE();
}
int32 readSint32LE() {
return (int32)readUint32LE();
}
int16 readSint16BE() {
return (int16)readUint16BE();
}
int32 readSint32BE() {
return (int32)readUint32BE();
}
};
/**
* 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) : _encbyte(enc), _realStream(in) {}
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() const { return _pos == _bufSize; }
uint32 pos() const { return _pos; }
uint32 size() const { return _bufSize; }
void seek(uint32 offs, int whence = SEEK_SET);
};
} // End of namespace Common
#endif
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