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Comparing liblzf/lzf_c.c (file contents):
Revision 1.3 by root, Sun Nov 17 11:39:26 2002 UTC vs.
Revision 1.38 by root, Sun May 30 05:46:56 2010 UTC

1/* 1/*
2 * Copyright (c) 2000-2002 Marc Alexander Lehmann <pcg@goof.com> 2 * Copyright (c) 2000-2009 Marc Alexander Lehmann <schmorp@schmorp.de>
3 * 3 *
4 * Redistribution and use in source and binary forms, with or without modifica- 4 * Redistribution and use in source and binary forms, with or without modifica-
5 * tion, are permitted provided that the following conditions are met: 5 * tion, are permitted provided that the following conditions are met:
6 * 6 *
7 * 1. Redistributions of source code must retain the above copyright notice, 7 * 1. Redistributions of source code must retain the above copyright notice,
8 * this list of conditions and the following disclaimer. 8 * this list of conditions and the following disclaimer.
9 * 9 *
10 * 2. Redistributions in binary form must reproduce the above copyright 10 * 2. Redistributions in binary form must reproduce the above copyright
11 * notice, this list of conditions and the following disclaimer in the 11 * notice, this list of conditions and the following disclaimer in the
12 * documentation and/or other materials provided with the distribution. 12 * documentation and/or other materials provided with the distribution.
13 *
14 * 3. The name of the author may not be used to endorse or promote products
15 * derived from this software without specific prior written permission.
16 * 13 *
17 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED 14 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
18 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MER- 15 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MER-
19 * CHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO 16 * CHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO
20 * EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPE- 17 * EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPE-
… …
22 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; 19 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
23 * OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, 20 * OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
24 * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTH- 21 * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTH-
25 * ERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED 22 * ERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
26 * OF THE POSSIBILITY OF SUCH DAMAGE. 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.
27 */ 35 */
28 36
29#include "lzfP.h" 37#include "lzfP.h"
30 38
31#define HSIZE (1 << (HLOG)) 39#define HSIZE (1 << (HLOG))
… …
34 * don't play with this unless you benchmark! 42 * don't play with this unless you benchmark!
35 * decompression is not dependent on the hash function 43 * decompression is not dependent on the hash function
36 * the hashing function might seem strange, just believe me 44 * the hashing function might seem strange, just believe me
37 * it works ;) 45 * it works ;)
38 */ 46 */
47#ifndef FRST
39#define FRST(p) (((p[0]) << 8) + p[1]) 48# define FRST(p) (((p[0]) << 8) | p[1])
40#define NEXT(v,p) (((v) << 8) + p[2]) 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
41#define IDX(h) ((((h ^ (h << 5)) >> (3*8 - HLOG)) + h*3) & (HSIZE - 1)) 55# define IDX(h) ((((h ^ (h << 5)) >> (3*8 - HLOG)) - h*5) & (HSIZE - 1))
56# endif
57#endif
42/* 58/*
43 * IDX works because it is very similar to a multiplicative hash, e.g. 59 * IDX works because it is very similar to a multiplicative hash, e.g.
44 * (h * 57321 >> (3*8 - HLOG)) 60 * ((h * 57321 >> (3*8 - HLOG)) & (HSIZE - 1))
61 * the latter is also quite fast on newer CPUs, and compresses similarly.
62 *
45 * the next one is also quite good, albeit slow ;) 63 * the next one is also quite good, albeit slow ;)
46 * (int)(cos(h & 0xffffff) * 1e6) 64 * (int)(cos(h & 0xffffff) * 1e6)
47 */ 65 */
48 66
49#if 0 67#if 0
50/* original lzv-like hash function */ 68/* original lzv-like hash function, much worse and thus slower */
51# define FRST(p) (p[0] << 5) ^ p[1] 69# define FRST(p) (p[0] << 5) ^ p[1]
52# define NEXT(v,p) ((v) << 5) ^ p[2] 70# define NEXT(v,p) ((v) << 5) ^ p[2]
53# define IDX(h) ((h) & (HSIZE - 1)) 71# define IDX(h) ((h) & (HSIZE - 1))
54#endif 72#endif
55 73
56#define MAX_LIT (1 << 5) 74#define MAX_LIT (1 << 5)
57#define MAX_OFF (1 << 13) 75#define MAX_OFF (1 << 13)
58#define MAX_REF ((1 << 8) + (1 << 3)) 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)
59 88
60/* 89/*
61 * compressed format 90 * compressed format
62 * 91 *
63 * 000LLLLL <L+1> ; literal 92 * 000LLLLL <L+1> ; literal, L+1=1..33 octets
64 * LLLOOOOO oooooooo ; backref L 93 * LLLooooo oooooooo ; backref L+1=1..7 octets, o+1=1..4096 offset
65 * 111OOOOO LLLLLLLL oooooooo ; backref L+7 94 * 111ooooo LLLLLLLL oooooooo ; backref L+8 octets, o+1=1..4096 offset
66 * 95 *
67 */ 96 */
68 97
69unsigned int 98unsigned int
70lzf_compress (const void *const in_data, unsigned int in_len, 99lzf_compress (const void *const in_data, unsigned int in_len,
71 void *out_data, unsigned int out_len) 100 void *out_data, unsigned int out_len
101#if LZF_STATE_ARG
102 , LZF_STATE htab
103#endif
104 )
72{ 105{
73 const u8 *htab[HSIZE]; 106#if !LZF_STATE_ARG
107 LZF_STATE htab;
108#endif
74 const u8 **hslot; 109 const u8 **hslot;
75 const u8 *ip = in_data; 110 const u8 *ip = (const u8 *)in_data;
76 u8 *op = out_data; 111 u8 *op = (u8 *)out_data;
77 const u8 *in_end = ip + in_len; 112 const u8 *in_end = ip + in_len;
78 u8 *out_end = op + out_len; 113 u8 *out_end = op + out_len;
79 const u8 *ref; 114 const u8 *ref;
80 115
81 unsigned int hval = FRST (ip); 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
82 unsigned long off; 126 unsigned long off;
83 int lit = 0; 127#endif
128 unsigned int hval;
129 int lit;
130
131 if (!in_len || !out_len)
132 return 0;
84 133
85#if INIT_HTAB 134#if INIT_HTAB
86# if USE_MEMCPY
87 memset (htab, 0, sizeof (htab)); 135 memset (htab, 0, sizeof (htab));
88# else 136# if 0
89 for (hslot = htab; hslot < htab + HSIZE; hslot++) 137 for (hslot = htab; hslot < htab + HSIZE; hslot++)
90 *hslot++ = ip; 138 *hslot++ = ip;
91# endif
92#endif 139# endif
140#endif
93 141
94 do 142 lit = 0; op++; /* start run */
143
144 hval = FRST (ip);
145 while (ip < in_end - 2)
95 { 146 {
96 hval = NEXT (hval, ip); 147 hval = NEXT (hval, ip);
97 hslot = htab + IDX (hval); 148 hslot = htab + IDX (hval);
98 ref = *hslot; *hslot = ip; 149 ref = *hslot; *hslot = ip;
99 150
100 if (1 151 if (1
101#if INIT_HTAB && !USE_MEMCPY 152#if INIT_HTAB
102 && ref < ip /* the next test will actually take care of this, but it is faster */ 153 && ref < ip /* the next test will actually take care of this, but this is faster */
103#endif 154#endif
104 && (off = ip - ref - 1) < MAX_OFF 155 && (off = ip - ref - 1) < MAX_OFF
105 && ip + 4 < in_end 156 && ip + 4 < in_end
106 && ref > (u8 *)in_data 157 && ref > (u8 *)in_data
107#if STRICT_ALIGN 158#if STRICT_ALIGN
108 && ref[0] == ip[0] 159 && ref[0] == ip[0]
109 && ref[1] == ip[1] 160 && ref[1] == ip[1]
110 && ref[2] == ip[2] 161 && ref[2] == ip[2]
111#else 162#else
112 && *(u16 *)ref == *(u16 *)ip 163 && *(u16 *)ref == *(u16 *)ip
113 && ref[2] == ip[2] 164 && ref[2] == ip[2]
114#endif 165#endif
115 ) 166 )
116 { 167 {
117 /* match found at *ref++ */ 168 /* match found at *ref++ */
118 unsigned int len = 2; 169 unsigned int len = 2;
119 unsigned int maxlen = in_end - ip - len; 170 unsigned int maxlen = in_end - ip - len;
120 maxlen = maxlen > MAX_REF ? MAX_REF : maxlen; 171 maxlen = maxlen > MAX_REF ? MAX_REF : maxlen;
121 172
122 do 173 if (expect_false (op + 3 + 1 >= out_end)) /* first a faster conservative test */
123 len++; 174 if (op - !lit + 3 + 1 >= out_end) /* second the exact but rare test */
175 return 0;
176
177 op [- lit - 1] = lit - 1; /* stop run */
178 op -= !lit; /* undo run if length is zero */
179
180 for (;;)
181 {
182 if (expect_true (maxlen > 16))
183 {
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 len++; if (ref [len] != ip [len]) break;
188
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 len++; if (ref [len] != ip [len]) break;
193
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 len++; if (ref [len] != ip [len]) break;
198
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 len++; if (ref [len] != ip [len]) break;
203 }
204
205 do
206 len++;
124 while (len < maxlen && ref[len] == ip[len]); 207 while (len < maxlen && ref[len] == ip[len]);
125 208
126 if (op + lit + 1 + 3 >= out_end) 209 break;
127 return 0; 210 }
128 211
129 if (lit) 212 len -= 2; /* len is now #octets - 1 */
130 { 213 ip++;
131 *op++ = lit - 1;
132 lit = -lit;
133 do
134 *op++ = ip[lit];
135 while (++lit);
136 }
137 214
138 len -= 2;
139 ip++;
140
141 if (len < 7) 215 if (len < 7)
142 { 216 {
143 *op++ = (off >> 8) + (len << 5); 217 *op++ = (off >> 8) + (len << 5);
144 } 218 }
145 else 219 else
146 { 220 {
147 *op++ = (off >> 8) + ( 7 << 5); 221 *op++ = (off >> 8) + ( 7 << 5);
148 *op++ = len - 7; 222 *op++ = len - 7;
149 } 223 }
150 224
151 *op++ = off; 225 *op++ = off;
226 lit = 0; op++; /* start run */
152 227
153#if ULTRA_FAST
154 ip += len; 228 ip += len + 1;
229
230 if (expect_false (ip >= in_end - 2))
231 break;
232
233#if ULTRA_FAST || VERY_FAST
234 --ip;
235# if VERY_FAST && !ULTRA_FAST
236 --ip;
237# endif
155 hval = FRST (ip); 238 hval = FRST (ip);
239
156 hval = NEXT (hval, ip); 240 hval = NEXT (hval, ip);
157 htab[IDX (hval)] = ip; 241 htab[IDX (hval)] = ip;
158 ip++; 242 ip++;
159#else 243
160 do 244# if VERY_FAST && !ULTRA_FAST
161 {
162 hval = NEXT (hval, ip); 245 hval = NEXT (hval, ip);
163 htab[IDX (hval)] = ip; 246 htab[IDX (hval)] = ip;
164 ip++; 247 ip++;
165 }
166 while (len--);
167#endif 248# endif
168 } 249#else
250 ip -= len + 1;
251
252 do
253 {
254 hval = NEXT (hval, ip);
255 htab[IDX (hval)] = ip;
256 ip++;
257 }
258 while (len--);
259#endif
260 }
169 else 261 else
170 { 262 {
171 /* one more literal byte we must copy */ 263 /* one more literal byte we must copy */
172 lit++; 264 if (expect_false (op >= out_end))
173 ip++; 265 return 0;
174 266
175 if (lit == MAX_LIT) 267 lit++; *op++ = *ip++;
176 {
177 if (op + 1 + MAX_LIT >= out_end)
178 return 0;
179 268
180 *op++ = MAX_LIT - 1; 269 if (expect_false (lit == MAX_LIT))
181#if USE_MEMCPY 270 {
182 memcpy (op, ip - MAX_LIT, MAX_LIT); 271 op [- lit - 1] = lit - 1; /* stop run */
183 op += MAX_LIT; 272 lit = 0; op++; /* start run */
184 lit = 0; 273 }
185#else 274 }
186 lit = -lit;
187 do
188 *op++ = ip[lit];
189 while (++lit);
190#endif
191 }
192 }
193 } 275 }
276
277 if (op + 3 > out_end) /* at most 3 bytes can be missing here */
278 return 0;
279
194 while (ip < in_end); 280 while (ip < in_end)
195
196 if (lit)
197 { 281 {
198 if (op + lit + 1 >= out_end) 282 lit++; *op++ = *ip++;
199 return 0;
200 283
201 *op++ = lit - 1; 284 if (expect_false (lit == MAX_LIT))
202 lit = -lit; 285 {
203 do 286 op [- lit - 1] = lit - 1; /* stop run */
204 *op++ = ip[lit]; 287 lit = 0; op++; /* start run */
205 while (++lit); 288 }
206 } 289 }
207 290
291 op [- lit - 1] = lit - 1; /* end run */
292 op -= !lit; /* undo run if length is zero */
293
208 return op - (u8 *) out_data; 294 return op - (u8 *)out_data;
209} 295}
296

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