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************************************************************************/ 30static NOINLINE unsigned 31do_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 */ 127match: 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************************************************************************/ 253int 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} 297