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d075193 @antirez new LZF files added
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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
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