1 /* 2 * Copyright (c) 2000-2010 Marc Alexander Lehmann <schmorp (at) schmorp.de> 3 * 4 * Redistribution and use in source and binary forms, with or without modifica- 5 * tion, are permitted provided that the following conditions are met: 6 * 7 * 1. Redistributions of source code must retain the above copyright notice, 8 * this list of conditions and the following disclaimer. 9 * 10 * 2. Redistributions in binary form must reproduce the above copyright 11 * notice, this list of conditions and the following disclaimer in the 12 * documentation and/or other materials provided with the distribution. 13 * 14 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED 15 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MER- 16 * CHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO 17 * EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPE- 18 * CIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, 19 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; 20 * OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, 21 * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTH- 22 * ERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED 23 * OF THE POSSIBILITY OF SUCH DAMAGE. 24 * 25 * Alternatively, the contents of this file may be used under the terms of 26 * the GNU General Public License ("GPL") version 2 or any later version, 27 * in which case the provisions of the GPL are applicable instead of 28 * the above. If you wish to allow the use of your version of this file 29 * only under the terms of the GPL and not to allow others to use your 30 * version of this file under the BSD license, indicate your decision 31 * by deleting the provisions above and replace them with the notice 32 * and other provisions required by the GPL. If you do not delete the 33 * provisions above, a recipient may use your version of this file under 34 * either the BSD or the GPL. 35 */ 36 37 #include "lzfP.h" 38 39 #define HSIZE (1 << (HLOG)) 40 41 /* 42 * don't play with this unless you benchmark! 43 * the data format is not dependent on the hash function. 44 * the hash function might seem strange, just believe me, 45 * it works ;) 46 */ 47 #ifndef FRST 48 # define FRST(p) (((p[0]) << 8) | p[1]) 49 # define NEXT(v,p) (((v) << 8) | p[2]) 50 # if ULTRA_FAST 51 # define IDX(h) ((( h >> (3*8 - HLOG)) - h ) & (HSIZE - 1)) 52 # elif VERY_FAST 53 # define IDX(h) ((( h >> (3*8 - HLOG)) - h*5) & (HSIZE - 1)) 54 # else 55 # define IDX(h) ((((h ^ (h << 5)) >> (3*8 - HLOG)) - h*5) & (HSIZE - 1)) 56 # endif 57 #endif 58 /* 59 * IDX works because it is very similar to a multiplicative hash, e.g. 60 * ((h * 57321 >> (3*8 - HLOG)) & (HSIZE - 1)) 61 * the latter is also quite fast on newer CPUs, and compresses similarly. 62 * 63 * the next one is also quite good, albeit slow ;) 64 * (int)(cos(h & 0xffffff) * 1e6) 65 */ 66 67 #if 0 68 /* original lzv-like hash function, much worse and thus slower */ 69 # define FRST(p) (p[0] << 5) ^ p[1] 70 # define NEXT(v,p) ((v) << 5) ^ p[2] 71 # define IDX(h) ((h) & (HSIZE - 1)) 72 #endif 73 74 #define MAX_LIT (1 << 5) 75 #define MAX_OFF (1 << 13) 76 #define MAX_REF ((1 << 8) + (1 << 3)) 77 78 #if __GNUC__ >= 3 79 # define expect(expr,value) __builtin_expect ((expr),(value)) 80 # define inline inline 81 #else 82 # define expect(expr,value) (expr) 83 # define inline static 84 #endif 85 86 #define expect_false(expr) expect ((expr) != 0, 0) 87 #define expect_true(expr) expect ((expr) != 0, 1) 88 89 /* 90 * compressed format 91 * 92 * 000LLLLL <L+1> ; literal, L+1=1..33 octets 93 * LLLooooo oooooooo ; backref L+1=1..7 octets, o+1=1..4096 offset 94 * 111ooooo LLLLLLLL oooooooo ; backref L+8 octets, o+1=1..4096 offset 95 * 96 */ 97 98 unsigned int 99 lzf_compress (const void *const in_data, unsigned int in_len, 100 void *out_data, unsigned int out_len 101 #if LZF_STATE_ARG 102 , LZF_STATE htab 103 #endif 104 ) 105 { 106 #if !LZF_STATE_ARG 107 LZF_STATE htab; 108 #endif 109 const u8 *ip = (const u8 *)in_data; 110 u8 *op = (u8 *)out_data; 111 const u8 *in_end = ip + in_len; 112 u8 *out_end = op + out_len; 113 const u8 *ref; 114 115 /* off requires a type wide enough to hold a general pointer difference. 116 * ISO C doesn't have that (size_t might not be enough and ptrdiff_t only 117 * works for differences within a single object). We also assume that no 118 * no bit pattern traps. Since the only platform that is both non-POSIX 119 * and fails to support both assumptions is windows 64 bit, we make a 120 * special workaround for it. 121 */ 122 #if defined (WIN32) && defined (_M_X64) 123 unsigned _int64 off; /* workaround for missing POSIX compliance */ 124 #else 125 unsigned long off; 126 #endif 127 unsigned int hval; 128 int lit; 129 130 if (!in_len || !out_len) 131 return 0; 132 133 #if INIT_HTAB 134 memset (htab, 0, sizeof (htab)); 135 #endif 136 137 lit = 0; op++; /* start run */ 138 139 hval = FRST (ip); 140 while (ip < in_end - 2) 141 { 142 LZF_HSLOT *hslot; 143 144 hval = NEXT (hval, ip); 145 hslot = htab + IDX (hval); 146 ref = *hslot + LZF_HSLOT_BIAS; *hslot = ip - LZF_HSLOT_BIAS; 147 148 if (1 149 #if INIT_HTAB 150 && ref < ip /* the next test will actually take care of this, but this is faster */ 151 #endif 152 && (off = ip - ref - 1) < MAX_OFF 153 && ref > (u8 *)in_data 154 && ref[2] == ip[2] 155 #if STRICT_ALIGN 156 && ((ref[1] << 8) | ref[0]) == ((ip[1] << 8) | ip[0]) 157 #else 158 && *(u16 *)ref == *(u16 *)ip 159 #endif 160 ) 161 { 162 /* match found at *ref++ */ 163 unsigned int len = 2; 164 unsigned int maxlen = in_end - ip - len; 165 maxlen = maxlen > MAX_REF ? MAX_REF : maxlen; 166 167 if (expect_false (op + 3 + 1 >= out_end)) /* first a faster conservative test */ 168 if (op - !lit + 3 + 1 >= out_end) /* second the exact but rare test */ 169 return 0; 170 171 op [- lit - 1] = lit - 1; /* stop run */ 172 op -= !lit; /* undo run if length is zero */ 173 174 for (;;) 175 { 176 if (expect_true (maxlen > 16)) 177 { 178 len++; if (ref [len] != ip [len]) break; 179 len++; if (ref [len] != ip [len]) break; 180 len++; if (ref [len] != ip [len]) break; 181 len++; if (ref [len] != ip [len]) break; 182 183 len++; if (ref [len] != ip [len]) break; 184 len++; if (ref [len] != ip [len]) break; 185 len++; if (ref [len] != ip [len]) break; 186 len++; if (ref [len] != ip [len]) break; 187 188 len++; if (ref [len] != ip [len]) break; 189 len++; if (ref [len] != ip [len]) break; 190 len++; if (ref [len] != ip [len]) break; 191 len++; if (ref [len] != ip [len]) break; 192 193 len++; if (ref [len] != ip [len]) break; 194 len++; if (ref [len] != ip [len]) break; 195 len++; if (ref [len] != ip [len]) break; 196 len++; if (ref [len] != ip [len]) break; 197 } 198 199 do 200 len++; 201 while (len < maxlen && ref[len] == ip[len]); 202 203 break; 204 } 205 206 len -= 2; /* len is now #octets - 1 */ 207 ip++; 208 209 if (len < 7) 210 { 211 *op++ = (off >> 8) + (len << 5); 212 } 213 else 214 { 215 *op++ = (off >> 8) + ( 7 << 5); 216 *op++ = len - 7; 217 } 218 219 *op++ = off; 220 221 lit = 0; op++; /* start run */ 222 223 ip += len + 1; 224 225 if (expect_false (ip >= in_end - 2)) 226 break; 227 228 #if ULTRA_FAST || VERY_FAST 229 --ip; 230 # if VERY_FAST && !ULTRA_FAST 231 --ip; 232 # endif 233 hval = FRST (ip); 234 235 hval = NEXT (hval, ip); 236 htab[IDX (hval)] = ip - LZF_HSLOT_BIAS; 237 ip++; 238 239 # if VERY_FAST && !ULTRA_FAST 240 hval = NEXT (hval, ip); 241 htab[IDX (hval)] = ip - LZF_HSLOT_BIAS; 242 ip++; 243 # endif 244 #else 245 ip -= len + 1; 246 247 do 248 { 249 hval = NEXT (hval, ip); 250 htab[IDX (hval)] = ip - LZF_HSLOT_BIAS; 251 ip++; 252 } 253 while (len--); 254 #endif 255 } 256 else 257 { 258 /* one more literal byte we must copy */ 259 if (expect_false (op >= out_end)) 260 return 0; 261 262 lit++; *op++ = *ip++; 263 264 if (expect_false (lit == MAX_LIT)) 265 { 266 op [- lit - 1] = lit - 1; /* stop run */ 267 lit = 0; op++; /* start run */ 268 } 269 } 270 } 271 272 if (op + 3 > out_end) /* at most 3 bytes can be missing here */ 273 return 0; 274 275 while (ip < in_end) 276 { 277 lit++; *op++ = *ip++; 278 279 if (expect_false (lit == MAX_LIT)) 280 { 281 op [- lit - 1] = lit - 1; /* stop run */ 282 lit = 0; op++; /* start run */ 283 } 284 } 285 286 op [- lit - 1] = lit - 1; /* end run */ 287 op -= !lit; /* undo run if length is zero */ 288 289 return op - (u8 *)out_data; 290 } 291 292
