release/src/router/lzo/src/lzo1f_1.c

   1 /* lzo1f_1.c -- implementation of the LZO1F-1 compression algorithm
   2
   3    This file is part of the LZO real-time data compression library.
   4
   5    Copyright (C) 1996-2015 Markus Franz Xaver Johannes Oberhumer
   6    All Rights Reserved.
   7
   8    The LZO 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 LZO 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 LZO library; see the file COPYING.
  20    If not, write to the Free Software Foundation, Inc.,
  21    51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
  22
  23    Markus F.X.J. Oberhumer
  24    <markus@oberhumer.com>
  25    http://www.oberhumer.com/opensource/lzo/
  26  */
  27
  28
  29 #include "lzo_conf.h"
  30 #include <lzo/lzo1f.h>
  31
  32
  33 /***********************************************************************
  34 //
  35 ************************************************************************/
  36
  37 #define M2_MAX_OFFSET   0x0800
  38 #define M3_MAX_OFFSET   0x3fff
  39 #define M3_MARKER       224
  40
  41
  42 #ifndef LZO_HASH
  43 #define LZO_HASH        LZO_HASH_LZO_INCREMENTAL_A
  44 #endif
  45 #define D_BITS          14
  46 #define D_INDEX1(d,p)   d = DM(DMUL(0x21,DX3(p,5,5,6)) >> 5)
  47 #define D_INDEX2(d,p)   d = (d & (D_MASK & 0x7ff)) ^ (D_HIGH | 0x1f)
  48 #include "lzo_dict.h"
  49
  50
  51 /***********************************************************************
  52 // compress a block of data.
  53 ************************************************************************/
  54
  55 static __lzo_noinline
  56 int do_compress          ( const lzo_bytep in , lzo_uint  in_len,
  57                                  lzo_bytep out, lzo_uintp out_len,
  58                                  lzo_voidp wrkmem )
  59 {
  60     const lzo_bytep ip;
  61     lzo_bytep op;
  62     const lzo_bytep const in_end = in + in_len;
  63     const lzo_bytep const ip_end = in + in_len - 9;
  64     const lzo_bytep ii;
  65     lzo_dict_p const dict = (lzo_dict_p) wrkmem;
  66
  67     op = out;
  68     ip = in;
  69     ii = ip;
  70
  71     ip++;
  72     for (;;)
  73     {
  74         const lzo_bytep m_pos;
  75         LZO_DEFINE_UNINITIALIZED_VAR(lzo_uint, m_off, 0);
  76         lzo_uint m_len;
  77         lzo_uint dindex;
  78         lzo_uint lit;
  79
  80         DINDEX1(dindex,ip);
  81         GINDEX(m_pos,m_off,dict,dindex,in);
  82         if (LZO_CHECK_MPOS_NON_DET(m_pos,m_off,in,ip,M3_MAX_OFFSET))
  83             goto literal;
  84 #if 1
  85         if (m_off <= M2_MAX_OFFSET || m_pos[3] == ip[3])
  86             goto try_match;
  87         DINDEX2(dindex,ip);
  88 #endif
  89         GINDEX(m_pos,m_off,dict,dindex,in);
  90         if (LZO_CHECK_MPOS_NON_DET(m_pos,m_off,in,ip,M3_MAX_OFFSET))
  91             goto literal;
  92         if (m_off <= M2_MAX_OFFSET || m_pos[3] == ip[3])
  93             goto try_match;
  94         goto literal;
  95
  96
  97 try_match:
  98 #if 0 && (LZO_OPT_UNALIGNED16)
  99         if (UA_GET_NE16(m_pos) != UA_GET_NE16(ip))
 100 #else
 101         if (m_pos[0] != ip[0] || m_pos[1] != ip[1])
 102 #endif
 103         {
 104         }
 105         else
 106         {
 107             if (m_pos[2] == ip[2])
 108             {
 109                 m_pos += 3;
 110 #if 0
 111                 if (m_off <= M2_MAX_OFFSET)
 112                     goto match;
 113                 if (lit <= 3)
 114                     goto match;
 115                 if (lit == 3)           /* better compression, but slower */
 116                 {
 117                     assert(op - 2 > out); op[-2] |= LZO_BYTE(3);
 118                     *op++ = *ii++; *op++ = *ii++; *op++ = *ii++;
 119                     goto code_match;
 120                 }
 121                 if (*m_pos == ip[3])
 122 #endif
 123                     goto match;
 124             }
 125         }
 126
 127
 128     /* a literal */
 129 literal:
 130         UPDATE_I(dict,0,dindex,ip,in);
 131         if (++ip >= ip_end)
 132             break;
 133         continue;
 134
 135
 136     /* a match */
 137 match:
 138         UPDATE_I(dict,0,dindex,ip,in);
 139         /* store current literal run */
 140         lit = pd(ip,ii);
 141         if (lit > 0)
 142         {
 143             lzo_uint t = lit;
 144
 145             if (t < 4 && op > out)
 146                 op[-2] = LZO_BYTE(op[-2] | t);
 147             else if (t <= 31)
 148                 *op++ = LZO_BYTE(t);
 149             else
 150             {
 151                 lzo_uint tt = t - 31;
 152
 153                 *op++ = 0;
 154                 while (tt > 255)
 155                 {
 156                     tt -= 255;
 157                     UA_SET1(op, 0);
 158                     op++;
 159                 }
 160                 assert(tt > 0);
 161                 *op++ = LZO_BYTE(tt);
 162             }
 163             do *op++ = *ii++; while (--t > 0);
 164         }
 165         assert(ii == ip);
 166
 167
 168         /* code the match */
 169         ip += 3;
 170         if (*m_pos++ != *ip++ || *m_pos++ != *ip++ || *m_pos++ != *ip++ ||
 171             *m_pos++ != *ip++ || *m_pos++ != *ip++ || *m_pos++ != *ip++)
 172         {
 173             --ip;
 174             m_len = pd(ip, ii);
 175             assert(m_len >= 3); assert(m_len <= 8);
 176
 177             if (m_off <= M2_MAX_OFFSET)
 178             {
 179                 m_off -= 1;
 180                 *op++ = LZO_BYTE(((m_len - 2) << 5) | ((m_off & 7) << 2));
 181                 *op++ = LZO_BYTE(m_off >> 3);
 182             }
 183             else if (m_len == 3 && m_off <= 2*M2_MAX_OFFSET && lit > 0)
 184             {
 185                 m_off -= 1;
 186                 /* m_off -= M2_MAX_OFFSET; */
 187                 *op++ = LZO_BYTE(((m_off & 7) << 2));
 188                 *op++ = LZO_BYTE(m_off >> 3);
 189             }
 190             else
 191             {
 192                 *op++ = LZO_BYTE(M3_MARKER | (m_len - 2));
 193                 *op++ = LZO_BYTE((m_off & 63) << 2);
 194                 *op++ = LZO_BYTE(m_off >> 6);
 195             }
 196         }
 197         else
 198         {
 199             {
 200                 const lzo_bytep end;
 201                 end = in_end;
 202                 while (ip < end && *m_pos == *ip)
 203                     m_pos++, ip++;
 204                 m_len = pd(ip, ii);
 205             }
 206             assert(m_len >= 3);
 207
 208             if (m_len <= 33)
 209                 *op++ = LZO_BYTE(M3_MARKER | (m_len - 2));
 210             else
 211             {
 212                 m_len -= 33;
 213                 *op++ = M3_MARKER | 0;
 214                 while (m_len > 255)
 215                 {
 216                     m_len -= 255;
 217                     UA_SET1(op, 0);
 218                     op++;
 219                 }
 220                 assert(m_len > 0);
 221                 *op++ = LZO_BYTE(m_len);
 222             }
 223             *op++ = LZO_BYTE((m_off & 63) << 2);
 224             *op++ = LZO_BYTE(m_off >> 6);
 225         }
 226
 227         ii = ip;
 228         if (ip >= ip_end)
 229             break;
 230     }
 231
 232
 233     /* store final literal run */
 234     if (pd(in_end,ii) > 0)
 235     {
 236         lzo_uint t = pd(in_end,ii);
 237
 238         if (t < 4 && op > out)
 239             op[-2] = LZO_BYTE(op[-2] | t);
 240         else if (t <= 31)
 241             *op++ = LZO_BYTE(t);
 242         else
 243         {
 244             lzo_uint tt = t - 31;
 245
 246             *op++ = 0;
 247             while (tt > 255)
 248             {
 249                 tt -= 255;
 250                 UA_SET1(op, 0);
 251                 op++;
 252             }
 253             assert(tt > 0);
 254             *op++ = LZO_BYTE(tt);
 255         }
 256         UA_COPYN(op, ii, t);
 257         op += t;
 258     }
 259
 260     *out_len = pd(op, out);
 261     return LZO_E_OK;
 262 }
 263
 264
 265 /***********************************************************************
 266 // public entry point
 267 ************************************************************************/
 268
 269 LZO_PUBLIC(int)
 270 lzo1f_1_compress ( const lzo_bytep in , lzo_uint  in_len,
 271                          lzo_bytep out, lzo_uintp out_len,
 272                          lzo_voidp wrkmem )
 273 {
 274     lzo_bytep op = out;
 275     int r = LZO_E_OK;
 276
 277     if (in_len == 0)
 278         *out_len = 0;
 279     else if (in_len <= 10)
 280     {
 281         *op++ = LZO_BYTE(in_len);
 282         do *op++ = *in++; while (--in_len > 0);
 283         *out_len = pd(op, out);
 284     }
 285     else
 286         r = do_compress(in,in_len,out,out_len,wrkmem);
 287
 288     if (r == LZO_E_OK)
 289     {
 290         op = out + *out_len;
 291         op[0] = M3_MARKER | 1;
 292         op[1] = 0;
 293         op[2] = 0;
 294         *out_len += 3;
 295     }
 296
 297     return r;
 298 }
 299
 300
 301 /* vim:set ts=4 sw=4 et: */