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pack.cpp

/* ScummVM - Scumm Interpreter
 * Copyright (C) 2004 Ivan Dubrov
 * Copyright (C) 2004-2005 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., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
 *
 * $Header: /cvsroot/scummvm/scummvm/gob/pack.cpp,v 1.5.2.1 2005/10/18 02:11:18 sev Exp $
 *
 */
#include "gob/gob.h"
#include "gob/pack.h"

namespace Gob {

int32 unpackData(char *sourceBuf, char *destBuf) {
      uint32 realSize;
      uint32 counter;
      uint16 cmd;
      byte *src;
      byte *dest;
      byte *tmpBuf;
      int16 off;
      byte len;
      byte i;
      int16 j;
      uint16 tmpIndex;

      realSize = READ_LE_UINT32(sourceBuf);
      counter = READ_LE_UINT32(sourceBuf);

      tmpBuf = (byte *)malloc(4114);

      /*
       * Can use assembler unpacker for small blocks - for speed.
       * Don't need this anymore :)
       */
      /*
       * if (realSize < 65000)
       * {
       * asm_unpackData(sourceBuf, destBuf, tmpBuf);
       * free(tmpBuf);
       * return realSize;
       * }
       */

      if (tmpBuf == 0)
            return 0;

      for (j = 0; j < 4078; j++)
            tmpBuf[j] = 0x20;
      tmpIndex = 4078;

      src = (byte *)(sourceBuf + 4);
      dest = (byte *)destBuf;

      cmd = 0;
      while (1) {
            cmd >>= 1;
            if ((cmd & 0x0100) == 0) {
                  cmd = *src | 0xff00;
                  src++;
            }
            if ((cmd & 1) != 0) {   /* copy */
                  *dest++ = *src;
                  tmpBuf[tmpIndex] = *src;
                  src++;
                  tmpIndex++;
                  tmpIndex %= 4096;
                  counter--;
                  if (counter == 0)
                        break;
            } else {    /* copy string */

                  off = *src++;
                  off |= (*src & 0xf0) << 4;
                  len = (*src & 0x0f) + 3;
                  src++;
                  for (i = 0; i < len; i++) {
                        *dest++ = tmpBuf[(off + i) % 4096];
                        counter--;
                        if (counter == 0) {
                              free(tmpBuf);
                              return realSize;
                        }
                        tmpBuf[tmpIndex] = tmpBuf[(off + i) % 4096];
                        tmpIndex++;
                        tmpIndex %= 4096;
                  }
            }
      }
      free(tmpBuf);
      return realSize;
}

}                       // End of namespace Gob

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