tools/ucl/src/n2e_d.c

   1 /* n2e_d.c -- implementation of the NRV2E decompression algorithm
   2
   3    This file is part of the UCL data compression library.
   4
   5    Copyright (C) 1996-2002 Markus Franz Xaver Johannes Oberhumer
   6    All Rights Reserved.
   7
   8    The UCL library is free software; you can redistribute it and/or
   9    modify it under the terms of the GNU General Public License as
  10    published by the Free Software Foundation; either version 2 of
  11    the License, or (at your option) any later version.
  12
  13    The UCL library is distributed in the hope that it will be useful,
  14    but WITHOUT ANY WARRANTY; without even the implied warranty of
  15    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16    GNU General Public License for more details.
  17
  18    You should have received a copy of the GNU General Public License
  19    along with the UCL library; see the file COPYING.
  20    If not, write to the Free Software Foundation, Inc.,
  21    59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
  22
  23    Markus F.X.J. Oberhumer
  24    <markus@oberhumer.com>
  25    http://www.oberhumer.com/opensource/ucl/
  26  */
  27
  28
  29 /***********************************************************************
  30 // actual implementation used by a recursive #include
  31 ************************************************************************/
  32
  33 #ifdef getbit
  34
  35 #ifdef SAFE
  36 #define fail(x,r)   if (x) { *dst_len = olen; return r; }
  37 #else
  38 #define fail(x,r)
  39 #endif
  40
  41 {
  42     ucl_uint32 bb = 0;
  43 #ifdef TEST_OVERLAP
  44     ucl_uint ilen = src_off, olen = 0, last_m_off = 1;
  45 #else
  46     ucl_uint ilen = 0, olen = 0, last_m_off = 1;
  47 #endif
  48 #ifdef SAFE
  49     const ucl_uint oend = *dst_len;
  50 #endif
  51     UCL_UNUSED(wrkmem);
  52
  53 #ifdef TEST_OVERLAP
  54     src_len += src_off;
  55     fail(oend >= src_len, UCL_E_OVERLAP_OVERRUN);
  56 #endif
  57
  58     for (;;)
  59     {
  60         ucl_uint m_off, m_len;
  61
  62         while (getbit(bb))
  63         {
  64             fail(ilen >= src_len, UCL_E_INPUT_OVERRUN);
  65             fail(olen >= oend, UCL_E_OUTPUT_OVERRUN);
  66 #ifdef TEST_OVERLAP
  67             fail(olen > ilen, UCL_E_OVERLAP_OVERRUN);
  68             olen++; ilen++;
  69 #else
  70             dst[olen++] = src[ilen++];
  71 #endif
  72         }
  73         m_off = 1;
  74         for (;;)
  75         {
  76             m_off = m_off*2 + getbit(bb);
  77             fail(ilen >= src_len, UCL_E_INPUT_OVERRUN);
  78             fail(m_off > UCL_UINT32_C(0xffffff) + 3, UCL_E_LOOKBEHIND_OVERRUN);
  79             if (getbit(bb)) break;
  80             m_off = (m_off-1)*2 + getbit(bb);
  81         }
  82         if (m_off == 2)
  83         {
  84             m_off = last_m_off;
  85             m_len = getbit(bb);
  86         }
  87         else
  88         {
  89             fail(ilen >= src_len, UCL_E_INPUT_OVERRUN);
  90             m_off = (m_off-3)*256 + src[ilen++];
  91             if (m_off == UCL_UINT32_C(0xffffffff))
  92                 break;
  93             m_len = (m_off ^ UCL_UINT32_C(0xffffffff)) & 1;
  94             m_off >>= 1;
  95             last_m_off = ++m_off;
  96         }
  97         if (m_len)
  98             m_len = 1 + getbit(bb);
  99         else if (getbit(bb))
 100             m_len = 3 + getbit(bb);
 101         else
 102         {
 103             m_len++;
 104             do {
 105                 m_len = m_len*2 + getbit(bb);
 106                 fail(ilen >= src_len, UCL_E_INPUT_OVERRUN);
 107                 fail(m_len >= oend, UCL_E_OUTPUT_OVERRUN);
 108             } while (!getbit(bb));
 109             m_len += 3;
 110         }
 111         m_len += (m_off > 0x500);
 112         fail(olen + m_len > oend, UCL_E_OUTPUT_OVERRUN);
 113         fail(m_off > olen, UCL_E_LOOKBEHIND_OVERRUN);
 114 #ifdef TEST_OVERLAP
 115         olen += m_len + 1;
 116         fail(olen > ilen, UCL_E_OVERLAP_OVERRUN);
 117 #else
 118         {
 119             const ucl_byte *m_pos;
 120             m_pos = dst + olen - m_off;
 121             dst[olen++] = *m_pos++;
 122             do dst[olen++] = *m_pos++; while (--m_len > 0);
 123         }
 124 #endif
 125     }
 126     *dst_len = olen;
 127     return ilen == src_len ? UCL_E_OK : (ilen < src_len ? UCL_E_INPUT_NOT_CONSUMED : UCL_E_INPUT_OVERRUN);
 128 }
 129
 130 #undef fail
 131
 132 #endif /* getbit */
 133
 134
 135 /***********************************************************************
 136 // decompressor entries for the different bit-buffer sizes
 137 ************************************************************************/
 138
 139 #ifndef getbit
 140
 141 #include <ucl/ucl.h>
 142 #include "ucl_conf.h"
 143 #include "getbit.h"
 144
 145
 146 UCL_PUBLIC(int)
 147 ucl_nrv2e_decompress_8          ( const ucl_byte *src, ucl_uint  src_len,
 148                                         ucl_byte *dst, ucl_uintp dst_len,
 149                                         ucl_voidp wrkmem )
 150 {
 151 #define getbit(bb)      getbit_8(bb,src,ilen)
 152 #include "n2e_d.c"
 153 #undef getbit
 154 }
 155
 156
 157 UCL_PUBLIC(int)
 158 ucl_nrv2e_decompress_le16       ( const ucl_bytep src, ucl_uint  src_len,
 159                                         ucl_bytep dst, ucl_uintp dst_len,
 160                                         ucl_voidp wrkmem )
 161 {
 162 #define getbit(bb)      getbit_le16(bb,src,ilen)
 163 #include "n2e_d.c"
 164 #undef getbit
 165 }
 166
 167
 168 UCL_PUBLIC(int)
 169 ucl_nrv2e_decompress_le32       ( const ucl_bytep src, ucl_uint  src_len,
 170                                         ucl_bytep dst, ucl_uintp dst_len,
 171                                         ucl_voidp wrkmem )
 172 {
 173     unsigned bc = 0;
 174 #define getbit(bb)      getbit_le32(bb,bc,src,ilen)
 175 #include "n2e_d.c"
 176 #undef getbit
 177 }
 178
 179
 180 #endif /* !getbit */
 181
 182
 183 /*
 184 vi:ts=4:et
 185 */
 186