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memstream.h

/* 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.
 *
 * $URL$
 * $Id$
 *
 */

#ifndef COMMON_MEMSTREAM_H
#define COMMON_MEMSTREAM_H

#include "common/stream.h"
#include "common/types.h"

namespace Common {

/**
 * Simple memory based 'stream', which implements the ReadStream interface for
 * a plain memory block.
 */
00038 class MemoryReadStream : public SeekableReadStream {
private:
      const byte * const _ptrOrig;
      const byte *_ptr;
      const uint32 _size;
      uint32 _pos;
      DisposeAfterUse::Flag _disposeMemory;
      bool _eos;

public:

      /**
       * This constructor takes a pointer to a memory buffer and a length, and
       * wraps it. If disposeMemory is true, the MemoryReadStream takes ownership
       * of the buffer and hence free's it when destructed.
       */
00054       MemoryReadStream(const byte *dataPtr, uint32 dataSize, DisposeAfterUse::Flag disposeMemory = DisposeAfterUse::NO) :
            _ptrOrig(dataPtr),
            _ptr(dataPtr),
            _size(dataSize),
            _pos(0),
            _disposeMemory(disposeMemory),
            _eos(false) {}

      ~MemoryReadStream() {
            if (_disposeMemory)
                  free(const_cast<byte *>(_ptrOrig));
      }

      uint32 read(void *dataPtr, uint32 dataSize);

00069       bool eos() const { return _eos; }
00070       void clearErr() { _eos = false; }

00072       int32 pos() const { return _pos; }
00073       int32 size() const { return _size; }

      bool seek(int32 offs, int whence = SEEK_SET);
};


/**
 * This is a MemoryReadStream subclass which adds non-endian
 * read methods whose endianness is set on the stream creation.
 */
00083 class MemoryReadStreamEndian : public MemoryReadStream, public ReadStreamEndian {
public:
      MemoryReadStreamEndian(const byte *buf, uint32 len, bool bigEndian)
            : MemoryReadStream(buf, len), ReadStreamEndian(bigEndian) {}
};

/**
 * Simple memory based 'stream', which implements the WriteStream interface for
 * a plain memory block.
 */
00093 class MemoryWriteStream : public WriteStream {
private:
      byte *_ptr;
      const uint32 _bufSize;
      uint32 _pos;
public:
      MemoryWriteStream(byte *buf, uint32 len) : _ptr(buf), _bufSize(len), _pos(0) {}

00101       uint32 write(const void *dataPtr, uint32 dataSize) {
            // Write at most as many bytes as are still available...
            if (dataSize > _bufSize - _pos)
                  dataSize = _bufSize - _pos;
            memcpy(_ptr, dataPtr, dataSize);
            _ptr += dataSize;
            _pos += dataSize;
            return dataSize;
      }

      uint32 pos() const { return _pos; }
      uint32 size() const { return _bufSize; }
};

/**
 * A sort of hybrid between MemoryWriteStream and Array classes. A stream
 * that grows as it's written to.
 */
00119 class MemoryWriteStreamDynamic : public WriteStream {
private:
      uint32 _capacity;
      uint32 _size;
      byte *_ptr;
      byte *_data;
      uint32 _pos;
      DisposeAfterUse::Flag _disposeMemory;

      void ensureCapacity(uint32 new_len) {
            if (new_len <= _capacity)
                  return;

            byte *old_data = _data;

            _capacity = new_len + 32;
            _data = (byte *)malloc(_capacity);
            _ptr = _data + _pos;

            if (old_data) {
                  // Copy old data
                  memcpy(_data, old_data, _size);
                  free(old_data);
            }

            _size = new_len;
      }
public:
      MemoryWriteStreamDynamic(DisposeAfterUse::Flag disposeMemory = DisposeAfterUse::NO) : _capacity(0), _size(0), _ptr(0), _data(0), _pos(0), _disposeMemory(disposeMemory) {}

      ~MemoryWriteStreamDynamic() {
            if (_disposeMemory)
                  free(_data);
      }

00154       uint32 write(const void *dataPtr, uint32 dataSize) {
            ensureCapacity(_pos + dataSize);
            memcpy(_ptr, dataPtr, dataSize);
            _ptr += dataSize;
            _pos += dataSize;
            if (_pos > _size)
                  _size = _pos;
            return dataSize;
      }

      uint32 pos() const { return _pos; }
      uint32 size() const { return _size; }

      byte *getData() { return _data; }

      bool seek(int32 offset, int whence = SEEK_SET);
};

}     // End of namespace Common

#endif

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