d0751937 |
1 | /* |
2 | * Copyright (c) 2000-2008 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 | * decompression is not dependent on the hash function |
44 | * the hashing 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 |
93 | * LLLooooo oooooooo ; backref L |
94 | * 111ooooo LLLLLLLL oooooooo ; backref L+7 |
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 **hslot; |
110 | const u8 *ip = (const u8 *)in_data; |
111 | u8 *op = (u8 *)out_data; |
112 | const u8 *in_end = ip + in_len; |
113 | u8 *out_end = op + out_len; |
114 | const u8 *ref; |
115 | |
116 | /* off requires a type wide enough to hold a general pointer difference. |
117 | * ISO C doesn't have that (size_t might not be enough and ptrdiff_t only |
118 | * works for differences within a single object). We also assume that no |
119 | * no bit pattern traps. Since the only platform that is both non-POSIX |
120 | * and fails to support both assumptions is windows 64 bit, we make a |
121 | * special workaround for it. |
122 | */ |
123 | #if defined (WIN32) && defined (_M_X64) |
124 | unsigned _int64 off; /* workaround for missing POSIX compliance */ |
125 | #else |
126 | unsigned long off; |
127 | #endif |
128 | unsigned int hval; |
129 | int lit; |
130 | |
131 | if (!in_len || !out_len) |
132 | return 0; |
133 | |
134 | #if INIT_HTAB |
135 | memset (htab, 0, sizeof (htab)); |
136 | # if 0 |
137 | for (hslot = htab; hslot < htab + HSIZE; hslot++) |
138 | *hslot++ = ip; |
139 | # endif |
140 | #endif |
141 | |
142 | lit = 0; op++; /* start run */ |
143 | |
144 | hval = FRST (ip); |
145 | while (ip < in_end - 2) |
146 | { |
147 | hval = NEXT (hval, ip); |
148 | hslot = htab + IDX (hval); |
149 | ref = *hslot; *hslot = ip; |
150 | |
151 | if (1 |
152 | #if INIT_HTAB |
153 | && ref < ip /* the next test will actually take care of this, but this is faster */ |
154 | #endif |
155 | && (off = ip - ref - 1) < MAX_OFF |
156 | && ip + 4 < in_end |
157 | && ref > (u8 *)in_data |
158 | #if STRICT_ALIGN |
159 | && ref[0] == ip[0] |
160 | && ref[1] == ip[1] |
161 | && ref[2] == ip[2] |
162 | #else |
163 | && *(u16 *)ref == *(u16 *)ip |
164 | && ref[2] == ip[2] |
165 | #endif |
166 | ) |
167 | { |
168 | /* match found at *ref++ */ |
169 | unsigned int len = 2; |
170 | unsigned int maxlen = in_end - ip - len; |
171 | maxlen = maxlen > MAX_REF ? MAX_REF : maxlen; |
172 | |
173 | op [- lit - 1] = lit - 1; /* stop run */ |
174 | op -= !lit; /* undo run if length is zero */ |
175 | |
176 | if (expect_false (op + 3 + 1 >= out_end)) |
177 | return 0; |
178 | |
179 | for (;;) |
180 | { |
181 | if (expect_true (maxlen > 16)) |
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 | len++; if (ref [len] != ip [len]) break; |
199 | len++; if (ref [len] != ip [len]) break; |
200 | len++; if (ref [len] != ip [len]) break; |
201 | len++; if (ref [len] != ip [len]) break; |
202 | } |
203 | |
204 | do |
205 | len++; |
206 | while (len < maxlen && ref[len] == ip[len]); |
207 | |
208 | break; |
209 | } |
210 | |
211 | len -= 2; /* len is now #octets - 1 */ |
212 | ip++; |
213 | |
214 | if (len < 7) |
215 | { |
216 | *op++ = (off >> 8) + (len << 5); |
217 | } |
218 | else |
219 | { |
220 | *op++ = (off >> 8) + ( 7 << 5); |
221 | *op++ = len - 7; |
222 | } |
223 | |
224 | *op++ = off; |
225 | lit = 0; op++; /* start run */ |
226 | |
227 | ip += len + 1; |
228 | |
229 | if (expect_false (ip >= in_end - 2)) |
230 | break; |
231 | |
232 | #if ULTRA_FAST || VERY_FAST |
233 | --ip; |
234 | # if VERY_FAST && !ULTRA_FAST |
235 | --ip; |
236 | # endif |
237 | hval = FRST (ip); |
238 | |
239 | hval = NEXT (hval, ip); |
240 | htab[IDX (hval)] = ip; |
241 | ip++; |
242 | |
243 | # if VERY_FAST && !ULTRA_FAST |
244 | hval = NEXT (hval, ip); |
245 | htab[IDX (hval)] = ip; |
246 | ip++; |
247 | # endif |
248 | #else |
249 | ip -= len + 1; |
250 | |
251 | do |
252 | { |
253 | hval = NEXT (hval, ip); |
254 | htab[IDX (hval)] = ip; |
255 | ip++; |
256 | } |
257 | while (len--); |
258 | #endif |
259 | } |
260 | else |
261 | { |
262 | /* one more literal byte we must copy */ |
263 | if (expect_false (op >= out_end)) |
264 | return 0; |
265 | |
266 | lit++; *op++ = *ip++; |
267 | |
268 | if (expect_false (lit == MAX_LIT)) |
269 | { |
270 | op [- lit - 1] = lit - 1; /* stop run */ |
271 | lit = 0; op++; /* start run */ |
272 | } |
273 | } |
274 | } |
275 | |
276 | if (op + 3 > out_end) /* at most 3 bytes can be missing here */ |
277 | return 0; |
278 | |
279 | while (ip < in_end) |
280 | { |
281 | lit++; *op++ = *ip++; |
282 | |
283 | if (expect_false (lit == MAX_LIT)) |
284 | { |
285 | op [- lit - 1] = lit - 1; /* stop run */ |
286 | lit = 0; op++; /* start run */ |
287 | } |
288 | } |
289 | |
290 | op [- lit - 1] = lit - 1; /* end run */ |
291 | op -= !lit; /* undo run if length is zero */ |
292 | |
293 | return op - (u8 *)out_data; |
294 | } |
295 | |