archival/libarchive/lzo1x_c.c

   1 /* implementation of the LZO1[XY]-1 compression algorithm
   2
   3    This file is part of the LZO real-time data compression library.
   4
   5    Copyright (C) 1996..2008 Markus Franz Xaver Johannes Oberhumer
   6    All Rights Reserved.
   7
   8    Markus F.X.J. Oberhumer <markus@oberhumer.com>
   9    http://www.oberhumer.com/opensource/lzo/
  10
  11    The LZO library is free software; you can redistribute it and/or
  12    modify it under the terms of the GNU General Public License as
  13    published by the Free Software Foundation; either version 2 of
  14    the License, or (at your option) any later version.
  15
  16    The LZO library is distributed in the hope that it will be useful,
  17    but WITHOUT ANY WARRANTY; without even the implied warranty of
  18    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  19    GNU General Public License for more details.
  20
  21    You should have received a copy of the GNU General Public License
  22    along with the LZO library; see the file COPYING.
  23    If not, write to the Free Software Foundation, Inc.,
  24    51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
  25  */
  26
  27 /***********************************************************************
  28 // compress a block of data.
  29 ************************************************************************/
  30 static NOINLINE unsigned
  31 do_compress(const uint8_t* in, unsigned in_len,
  32                 uint8_t* out, unsigned* out_len,
  33                 void* wrkmem)
  34 {
  35         register const uint8_t* ip;
  36         uint8_t* op;
  37         const uint8_t* const in_end = in + in_len;
  38         const uint8_t* const ip_end = in + in_len - M2_MAX_LEN - 5;
  39         const uint8_t* ii;
  40         const void* *const dict = (const void**) wrkmem;
  41
  42         op = out;
  43         ip = in;
  44         ii = ip;
  45
  46         ip += 4;
  47         for (;;) {
  48                 register const uint8_t* m_pos;
  49                 unsigned m_off;
  50                 unsigned m_len;
  51                 unsigned dindex;
  52
  53                 D_INDEX1(dindex,ip);
  54                 GINDEX(m_pos,m_off,dict,dindex,in);
  55                 if (LZO_CHECK_MPOS_NON_DET(m_pos,m_off,in,ip,M4_MAX_OFFSET))
  56                         goto literal;
  57 #if 1
  58                 if (m_off <= M2_MAX_OFFSET || m_pos[3] == ip[3])
  59                         goto try_match;
  60                 D_INDEX2(dindex,ip);
  61 #endif
  62                 GINDEX(m_pos,m_off,dict,dindex,in);
  63                 if (LZO_CHECK_MPOS_NON_DET(m_pos,m_off,in,ip,M4_MAX_OFFSET))
  64                         goto literal;
  65                 if (m_off <= M2_MAX_OFFSET || m_pos[3] == ip[3])
  66                         goto try_match;
  67                 goto literal;
  68
  69  try_match:
  70 #if 1 && defined(LZO_UNALIGNED_OK_2)
  71                 if (* (const lzo_ushortp) m_pos != * (const lzo_ushortp) ip)
  72 #else
  73                 if (m_pos[0] != ip[0] || m_pos[1] != ip[1])
  74 #endif
  75                 {
  76                 } else {
  77                         if (m_pos[2] == ip[2]) {
  78 #if 0
  79                                 if (m_off <= M2_MAX_OFFSET)
  80                                         goto match;
  81                                 if (lit <= 3)
  82                                         goto match;
  83                                 if (lit == 3) {                   /* better compression, but slower */
  84                                         assert(op - 2 > out); op[-2] |= (uint8_t)(3);
  85                                         *op++ = *ii++; *op++ = *ii++; *op++ = *ii++;
  86                                         goto code_match;
  87                                 }
  88                                 if (m_pos[3] == ip[3])
  89 #endif
  90                                         goto match;
  91                         }
  92                         else {
  93                                 /* still need a better way for finding M1 matches */
  94 #if 0
  95                                 /* a M1 match */
  96 #if 0
  97                                 if (m_off <= M1_MAX_OFFSET && lit > 0 && lit <= 3)
  98 #else
  99                                 if (m_off <= M1_MAX_OFFSET && lit == 3)
 100 #endif
 101                                 {
 102                                         register unsigned t;
 103
 104                                         t = lit;
 105                                         assert(op - 2 > out); op[-2] |= (uint8_t)(t);
 106                                         do *op++ = *ii++; while (--t > 0);
 107                                         assert(ii == ip);
 108                                         m_off -= 1;
 109                                         *op++ = (uint8_t)(M1_MARKER | ((m_off & 3) << 2));
 110                                         *op++ = (uint8_t)(m_off >> 2);
 111                                         ip += 2;
 112                                         goto match_done;
 113                                 }
 114 #endif
 115                         }
 116                 }
 117
 118                 /* a literal */
 119  literal:
 120                 UPDATE_I(dict, 0, dindex, ip, in);
 121                 ++ip;
 122                 if (ip >= ip_end)
 123                         break;
 124                 continue;
 125
 126                 /* a match */
 127 match:
 128                 UPDATE_I(dict, 0, dindex, ip, in);
 129                 /* store current literal run */
 130                 if (pd(ip, ii) > 0) {
 131                         register unsigned t = pd(ip, ii);
 132
 133                         if (t <= 3) {
 134                                 assert(op - 2 > out);
 135                                 op[-2] |= (uint8_t)(t);
 136                         }
 137                         else if (t <= 18)
 138                                 *op++ = (uint8_t)(t - 3);
 139                         else {
 140                                 register unsigned tt = t - 18;
 141
 142                                 *op++ = 0;
 143                                 while (tt > 255) {
 144                                         tt -= 255;
 145                                         *op++ = 0;
 146                                 }
 147                                 assert(tt > 0);
 148                                 *op++ = (uint8_t)(tt);
 149                         }
 150                         do *op++ = *ii++; while (--t > 0);
 151                 }
 152
 153                 /* code the match */
 154                 assert(ii == ip);
 155                 ip += 3;
 156                 if (m_pos[3] != *ip++ || m_pos[4] != *ip++ || m_pos[5] != *ip++
 157                  || m_pos[6] != *ip++ || m_pos[7] != *ip++ || m_pos[8] != *ip++
 158 #ifdef LZO1Y
 159                  || m_pos[ 9] != *ip++ || m_pos[10] != *ip++ || m_pos[11] != *ip++
 160                  || m_pos[12] != *ip++ || m_pos[13] != *ip++ || m_pos[14] != *ip++
 161 #endif
 162                 ) {
 163                         --ip;
 164                         m_len = pd(ip, ii);
 165                         assert(m_len >= 3);
 166                         assert(m_len <= M2_MAX_LEN);
 167
 168                         if (m_off <= M2_MAX_OFFSET) {
 169                                 m_off -= 1;
 170 #if defined(LZO1X)
 171                                 *op++ = (uint8_t)(((m_len - 1) << 5) | ((m_off & 7) << 2));
 172                                 *op++ = (uint8_t)(m_off >> 3);
 173 #elif defined(LZO1Y)
 174                                 *op++ = (uint8_t)(((m_len + 1) << 4) | ((m_off & 3) << 2));
 175                                 *op++ = (uint8_t)(m_off >> 2);
 176 #endif
 177                         }
 178                         else if (m_off <= M3_MAX_OFFSET) {
 179                                 m_off -= 1;
 180                                 *op++ = (uint8_t)(M3_MARKER | (m_len - 2));
 181                                 goto m3_m4_offset;
 182                         } else {
 183 #if defined(LZO1X)
 184                                 m_off -= 0x4000;
 185                                 assert(m_off > 0);
 186                                 assert(m_off <= 0x7fff);
 187                                 *op++ = (uint8_t)(M4_MARKER | ((m_off & 0x4000) >> 11) | (m_len - 2));
 188                                 goto m3_m4_offset;
 189 #elif defined(LZO1Y)
 190                                 goto m4_match;
 191 #endif
 192                         }
 193                 }
 194                 else {
 195                         {
 196                                 const uint8_t* end = in_end;
 197                                 const uint8_t* m = m_pos + M2_MAX_LEN + 1;
 198                                 while (ip < end && *m == *ip)
 199                                         m++, ip++;
 200                                 m_len = pd(ip, ii);
 201                         }
 202                         assert(m_len > M2_MAX_LEN);
 203
 204                         if (m_off <= M3_MAX_OFFSET) {
 205                                 m_off -= 1;
 206                                 if (m_len <= 33)
 207                                         *op++ = (uint8_t)(M3_MARKER | (m_len - 2));
 208                                 else {
 209                                         m_len -= 33;
 210                                         *op++ = M3_MARKER | 0;
 211                                         goto m3_m4_len;
 212                                 }
 213                         } else {
 214 #if defined(LZO1Y)
 215  m4_match:
 216 #endif
 217                                 m_off -= 0x4000;
 218                                 assert(m_off > 0);
 219                                 assert(m_off <= 0x7fff);
 220                                 if (m_len <= M4_MAX_LEN)
 221                                         *op++ = (uint8_t)(M4_MARKER | ((m_off & 0x4000) >> 11) | (m_len - 2));
 222                                 else {
 223                                         m_len -= M4_MAX_LEN;
 224                                         *op++ = (uint8_t)(M4_MARKER | ((m_off & 0x4000) >> 11));
 225  m3_m4_len:
 226                                         while (m_len > 255) {
 227                                                 m_len -= 255;
 228                                                 *op++ = 0;
 229                                         }
 230                                         assert(m_len > 0);
 231                                         *op++ = (uint8_t)(m_len);
 232                                 }
 233                         }
 234  m3_m4_offset:
 235                         *op++ = (uint8_t)((m_off & 63) << 2);
 236                         *op++ = (uint8_t)(m_off >> 6);
 237                 }
 238 #if 0
 239  match_done:
 240 #endif
 241                 ii = ip;
 242                 if (ip >= ip_end)
 243                         break;
 244         }
 245
 246         *out_len = pd(op, out);
 247         return pd(in_end, ii);
 248 }
 249
 250 /***********************************************************************
 251 // public entry point
 252 ************************************************************************/
 253 int DO_COMPRESS(const uint8_t* in, unsigned in_len,
 254                 uint8_t* out, unsigned* out_len,
 255                 void* wrkmem)
 256 {
 257         uint8_t* op = out;
 258         unsigned t;
 259
 260         if (in_len <= M2_MAX_LEN + 5)
 261                 t = in_len;
 262         else {
 263                 t = do_compress(in,in_len,op,out_len,wrkmem);
 264                 op += *out_len;
 265         }
 266
 267         if (t > 0) {
 268                 const uint8_t* ii = in + in_len - t;
 269
 270                 if (op == out && t <= 238)
 271                         *op++ = (uint8_t)(17 + t);
 272                 else if (t <= 3)
 273                         op[-2] |= (uint8_t)(t);
 274                 else if (t <= 18)
 275                         *op++ = (uint8_t)(t - 3);
 276                 else {
 277                         unsigned tt = t - 18;
 278
 279                         *op++ = 0;
 280                         while (tt > 255) {
 281                                 tt -= 255;
 282                                 *op++ = 0;
 283                         }
 284                         assert(tt > 0);
 285                         *op++ = (uint8_t)(tt);
 286                 }
 287                 do *op++ = *ii++; while (--t > 0);
 288         }
 289
 290         *op++ = M4_MARKER | 1;
 291         *op++ = 0;
 292         *op++ = 0;
 293
 294         *out_len = pd(op, out);
 295         return 0; /*LZO_E_OK*/
 296 }