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| 1 | +/* |
| 2 | + * Copyright (c) 2000-2010 Marc Alexander Lehmann <schmorp@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 | + |
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