David Li | e54acca | 2011-03-18 16:21:06 -0700 | [diff] [blame] | 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 | |