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
lzf_compress(const void * const in_data,unsigned int in_len,void * out_data,unsigned int out_len,LZF_STATE htab)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