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 #if defined(_KERNEL) || defined (_STANDALONE)
38 #include <lib/libkern/libkern.h>
39 #include "lzfP.h"
40 #else
41 #include "lzf.h"
42 #endif
43
44 #define HSIZE (1 << (LZF_HLOG))
45
46 /*
47 * don't play with this unless you benchmark!
48 * decompression is not dependent on the hash function
49 * the hashing function might seem strange, just believe me
50 * it works ;)
51 */
52 #ifndef FRST
53 # define FRST(p) (((p[0]) << 8) | p[1])
54 # define NEXT(v,p) (((v) << 8) | p[2])
55 # if ULTRA_FAST
56 # define IDX(h) ((( h >> (3*8 - LZF_HLOG)) - h ) & (HSIZE - 1))
57 # elif VERY_FAST
58 # define IDX(h) ((( h >> (3*8 - LZF_HLOG)) - h*5) & (HSIZE - 1))
59 # else
60 # define IDX(h) ((((h ^ (h << 5)) >> (3*8 - LZF_HLOG)) - h*5) & (HSIZE - 1))
61 # endif
62 #endif
63 /*
64 * IDX works because it is very similar to a multiplicative hash, e.g.
65 * ((h * 57321 >> (3*8 - LZF_HLOG)) & (HSIZE - 1))
66 * the latter is also quite fast on newer CPUs, and compresses similarly.
67 *
68 * the next one is also quite good, albeit slow ;)
69 * (int)(cos(h & 0xffffff) * 1e6)
70 */
71
72 #if 0
73 /* original lzv-like hash function, much worse and thus slower */
74 # define FRST(p) (p[0] << 5) ^ p[1]
75 # define NEXT(v,p) ((v) << 5) ^ p[2]
76 # define IDX(h) ((h) & (HSIZE - 1))
77 #endif
78
79 #define MAX_LIT (1 << 5)
80 #define MAX_OFF (1 << 13)
81 #define MAX_REF ((1 << 8) + (1 << 3))
82
83 #if __GNUC__ >= 3
84 # define expect(expr,value) __builtin_expect ((expr),(value))
85 # define inline inline
86 #else
87 # define expect(expr,value) (expr)
88 # define inline static
89 #endif
90
91 #define expect_false(expr) expect ((expr) != 0, 0)
92 #define expect_true(expr) expect ((expr) != 0, 1)
93
94 /*
95 * compressed format
96 *
97 * 000LLLLL <L+1> ; literal
98 * LLLooooo oooooooo ; backref L
99 * 111ooooo LLLLLLLL oooooooo ; backref L+7
100 *
101 */
102
103 unsigned int
lzf_compress_r(const void * const in_data,unsigned int in_len,void * out_data,unsigned int out_len,LZF_STATE htab)104 lzf_compress_r (const void *const in_data, unsigned int in_len,
105 void *out_data, unsigned int out_len, LZF_STATE htab)
106 {
107 const u8 **hslot;
108 const u8 *ip = (const u8 *)in_data;
109 u8 *op = (u8 *)out_data;
110 const u8 *in_end = ip + in_len;
111 u8 *out_end = op + out_len;
112 const u8 *ref;
113
114 /* off requires a type wide enough to hold a general pointer difference.
115 * ISO C doesn't have that (size_t might not be enough and ptrdiff_t only
116 * works for differences within a single object). We also assume that no
117 * no bit pattern traps. Since the only platform that is both non-POSIX
118 * and fails to support both assumptions is windows 64 bit, we make a
119 * special workaround for it.
120 */
121 #if defined (WIN32) && defined (_M_X64)
122 unsigned _int64 off; /* workaround for missing POSIX compliance */
123 #else
124 unsigned long off;
125 #endif
126 unsigned int hval;
127 int lit;
128
129 if (!in_len || !out_len)
130 return 0;
131
132 #if INIT_HTAB
133 memset (htab, 0, sizeof (htab));
134 # if 0
135 for (hslot = htab; hslot < htab + HSIZE; hslot++)
136 *hslot++ = ip;
137 # endif
138 #endif
139
140 lit = 0; op++; /* start run */
141
142 hval = FRST (ip);
143 while (ip < in_end - 2)
144 {
145 hval = NEXT (hval, ip);
146 hslot = htab + IDX (hval);
147 ref = *hslot; *hslot = ip;
148
149 if (/*CONSTCOND*/1
150 #if INIT_HTAB
151 && ref < ip /* the next test will actually take care of this, but this is faster */
152 #endif
153 && (off = ip - ref - 1) < MAX_OFF
154 && ip + 4 < in_end
155 && ref > (const u8 *)in_data
156 #if STRICT_ALIGN
157 && ref[0] == ip[0]
158 && ref[1] == ip[1]
159 && ref[2] == ip[2]
160 #else
161 && *(const u16 *)(const void *)ref == *(const u16 *)(const void *)ip
162 && ref[2] == ip[2]
163 #endif
164 )
165 {
166 /* match found at *ref++ */
167 unsigned int len = 2;
168 unsigned int maxlen = (unsigned)(in_end - ip) - len;
169 maxlen = maxlen > MAX_REF ? MAX_REF : maxlen;
170
171 if (expect_false (op + 3 + 1 >= out_end)) /* first a faster conservative test */
172 if (op - !lit + 3 + 1 >= out_end) /* second the exact but rare test */
173 return 0;
174
175 op [- lit - 1] = lit - 1; /* stop run */
176 op -= !lit; /* undo run if length is zero */
177
178 for (;;)
179 {
180 if (expect_true (maxlen > 16))
181 {
182 len++; if (ref [len] != ip [len]) break;
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
187 len++; if (ref [len] != ip [len]) break;
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
192 len++; if (ref [len] != ip [len]) break;
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
197 len++; if (ref [len] != ip [len]) break;
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 }
202
203 do
204 len++;
205 while (len < maxlen && ref[len] == ip[len]);
206
207 break;
208 }
209
210 len -= 2; /* len is now #octets - 1 */
211 ip++;
212
213 if (len < 7)
214 {
215 *op++ = (unsigned char)((off >> 8) + (len << 5));
216 }
217 else
218 {
219 *op++ = (unsigned char)((off >> 8) + ( 7 << 5));
220 *op++ = len - 7;
221 }
222
223 *op++ = (unsigned char)off;
224 lit = 0; op++; /* start run */
225
226 ip += len + 1;
227
228 if (expect_false (ip >= in_end - 2))
229 break;
230
231 #if ULTRA_FAST || VERY_FAST
232 --ip;
233 # if VERY_FAST && !ULTRA_FAST
234 --ip;
235 # endif
236 hval = FRST (ip);
237
238 hval = NEXT (hval, ip);
239 htab[IDX (hval)] = ip;
240 ip++;
241
242 # if VERY_FAST && !ULTRA_FAST
243 hval = NEXT (hval, ip);
244 htab[IDX (hval)] = ip;
245 ip++;
246 # endif
247 #else
248 ip -= len + 1;
249
250 do
251 {
252 hval = NEXT (hval, ip);
253 htab[IDX (hval)] = ip;
254 ip++;
255 }
256 while (len--);
257 #endif
258 }
259 else
260 {
261 /* one more literal byte we must copy */
262 if (expect_false (op >= out_end))
263 return 0;
264
265 lit++; *op++ = *ip++;
266
267 /*LINTED*/
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 /*LINTED*/
284 if (expect_false (lit == MAX_LIT))
285 {
286 op [- lit - 1] = lit - 1; /* stop run */
287 lit = 0; op++; /* start run */
288 }
289 }
290
291 op [- lit - 1] = lit - 1; /* end run */
292 op -= !lit; /* undo run if length is zero */
293
294 return (unsigned)(op - (u8 *)out_data);
295 }
296