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  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) 1996-2004 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.     ACC_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_bytep 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_conf.h"
  142. #include <ucl/ucl.h>
  143. #include "getbit.h"
  144.  
  145.  
  146. UCL_PUBLIC(int)
  147. ucl_nrv2e_decompress_8          ( const ucl_bytep src, ucl_uint  src_len,
  148.                                         ucl_bytep 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.  
  187.