fbreader/src/formats/pdb/DocDecompressor.cpp

   1 /*
   2  * Copyright (C) 2004-2008 Geometer Plus <contact@geometerplus.com>
   3  *
   4  * This program is free software; you can redistribute it and/or modify
   5  * it under the terms of the GNU General Public License as published by
   6  * the Free Software Foundation; either version 2 of the License, or
   7  * (at your option) any later version.
   8  *
   9  * This program is distributed in the hope that it will be useful,
  10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12  * GNU General Public License for more details.
  13  *
  14  * You should have received a copy of the GNU General Public License
  15  * along with this program; if not, write to the Free Software
  16  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
  17  * 02110-1301, USA.
  18  */
  19
  20 #include <string.h>
  21
  22 #include <ZLInputStream.h>
  23
  24 #include "DocDecompressor.h"
  25
  26 static unsigned char TOKEN_CODE[256] = {
  27         0, 1, 1, 1,             1, 1, 1, 1,             1, 0, 0, 0,             0, 0, 0, 0,
  28         0, 0, 0, 0,             0, 0, 0, 0,             0, 0, 0, 0,             0, 0, 0, 0,
  29         0, 0, 0, 0,             0, 0, 0, 0,             0, 0, 0, 0,             0, 0, 0, 0,
  30         0, 0, 0, 0,             0, 0, 0, 0,             0, 0, 0, 0,             0, 0, 0, 0,
  31         0, 0, 0, 0,             0, 0, 0, 0,             0, 0, 0, 0,             0, 0, 0, 0,
  32         0, 0, 0, 0,             0, 0, 0, 0,             0, 0, 0, 0,             0, 0, 0, 0,
  33         0, 0, 0, 0,             0, 0, 0, 0,             0, 0, 0, 0,             0, 0, 0, 0,
  34         0, 0, 0, 0,             0, 0, 0, 0,             0, 0, 0, 0,             0, 0, 0, 0,
  35         3, 3, 3, 3,             3, 3, 3, 3,             3, 3, 3, 3,             3, 3, 3, 3,
  36         3, 3, 3, 3,             3, 3, 3, 3,             3, 3, 3, 3,             3, 3, 3, 3,
  37         3, 3, 3, 3,             3, 3, 3, 3,             3, 3, 3, 3,             3, 3, 3, 3,
  38         3, 3, 3, 3,             3, 3, 3, 3,             3, 3, 3, 3,             3, 3, 3, 3,
  39         2, 2, 2, 2,             2, 2, 2, 2,             2, 2, 2, 2,             2, 2, 2, 2,
  40         2, 2, 2, 2,             2, 2, 2, 2,             2, 2, 2, 2,             2, 2, 2, 2,
  41         2, 2, 2, 2,             2, 2, 2, 2,             2, 2, 2, 2,             2, 2, 2, 2,
  42         2, 2, 2, 2,             2, 2, 2, 2,             2, 2, 2, 2,             2, 2, 2, 2,
  43 };
  44
  45 size_t DocDecompressor::decompress(ZLInputStream &stream, char *targetBuffer, size_t compressedSize, size_t maxUncompressedSize) {
  46         const unsigned char *sourceBuffer = new unsigned char[compressedSize];
  47         const unsigned char *sourceBufferEnd = sourceBuffer + compressedSize;
  48         const unsigned char *sourcePtr = sourceBuffer;
  49
  50         unsigned char *targetBufferEnd = (unsigned char*)targetBuffer + maxUncompressedSize;
  51         unsigned char *targetPtr = (unsigned char*)targetBuffer;
  52
  53         if (stream.read((char*)sourceBuffer, compressedSize) == compressedSize) {
  54                 unsigned char token;
  55                 unsigned short copyLength, N, shift;
  56                 unsigned char *shifted;
  57
  58                 while ((sourcePtr < sourceBufferEnd) && (targetPtr < targetBufferEnd)) {
  59                         token = *(sourcePtr++);
  60                         switch (TOKEN_CODE[token]) {
  61                                 case 0:
  62                                         *(targetPtr++) = token;
  63                                         break;
  64                                 case 1:
  65                                         if ((sourcePtr + token > sourceBufferEnd) || (targetPtr + token > targetBufferEnd)) {
  66                                                 goto endOfLoop;
  67                                         }
  68                                         memcpy(targetPtr, sourcePtr, token);
  69                                         sourcePtr += token;
  70                                         targetPtr += token;
  71                                         break;
  72                                 case 2:
  73                                         if (targetPtr + 2 > targetBufferEnd) {
  74                                                 goto endOfLoop;
  75                                         }
  76                                         *(targetPtr++) = ' ';
  77                                         *(targetPtr++) = token ^ 0x80;
  78                                         break;
  79                                 case 3:
  80                                         if (sourcePtr + 1 > sourceBufferEnd) {
  81                                                 goto endOfLoop;
  82                                         }
  83                                         N = 256 * token + *(sourcePtr++);
  84                                         copyLength = (N & 7) + 3;
  85                                         if (targetPtr + copyLength > targetBufferEnd) {
  86                                                 goto endOfLoop;
  87                                         }
  88                                         shift = (N & 0x3fff) / 8;
  89                                         shifted = targetPtr - shift;
  90                                         if ((char*)shifted >= targetBuffer) {
  91                                                 for (short i = 0; i < copyLength; i++) {
  92                                                         *(targetPtr++) = *(shifted++);
  93                                                 }
  94                                         }
  95                                         break;
  96                         }
  97                 }
  98         }
  99 endOfLoop:
 100
 101         delete[] sourceBuffer;
 102         return targetPtr - (unsigned char*)targetBuffer;
 103 }