1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
|
/*
* Copyright (c) 2000-2003 Marc Alexander Lehmann <pcg@goof.com>
*
* Redistribution and use in source and binary forms, with or without modifica-
* tion, are permitted provided that the following conditions are met:
*
* 1. Redistributions of source code must retain the above copyright notice,
* this list of conditions and the following disclaimer.
*
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* 3. The name of the author may not be used to endorse or promote products
* derived from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
* WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MER-
* CHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO
* EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPE-
* CIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
* PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
* OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
* WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTH-
* ERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
* OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#include "lzfP.h"
#define HSIZE (1 << (HLOG))
/*
* don't play with this unless you benchmark!
* decompression is not dependent on the hash function
* the hashing function might seem strange, just believe me
* it works ;)
*/
#define FRST(p) (((p[0]) << 8) + p[1])
#define NEXT(v,p) (((v) << 8) + p[2])
#define IDX(h) ((((h ^ (h << 5)) >> (3*8 - HLOG)) + h*3) & (HSIZE - 1))
/*
* IDX works because it is very similar to a multiplicative hash, e.g.
* (h * 57321 >> (3*8 - HLOG))
* the next one is also quite good, albeit slow ;)
* (int)(cos(h & 0xffffff) * 1e6)
*/
#if 0
/* original lzv-like hash function */
# define FRST(p) (p[0] << 5) ^ p[1]
# define NEXT(v,p) ((v) << 5) ^ p[2]
# define IDX(h) ((h) & (HSIZE - 1))
#endif
#define MAX_LIT (1 << 5)
#define MAX_OFF (1 << 13)
#define MAX_REF ((1 << 8) + (1 << 3))
/*
* compressed format
*
* 000LLLLL <L+1> ; literal
* LLLOOOOO oooooooo ; backref L
* 111OOOOO LLLLLLLL oooooooo ; backref L+7
*
*/
unsigned int
lzf_compress (const void *const in_data, unsigned int in_len,
void *out_data, unsigned int out_len
#if !LZF_STATE_ARG
, LZF_STATE *htab
#endif
)
{
#if LZF_STATE_ARG
LZF_STATE htab;
#endif
const u8 **hslot;
const u8 *ip = (const u8 *)in_data;
u8 *op = (u8 *)out_data;
const u8 *in_end = ip + in_len;
u8 *out_end = op + out_len;
const u8 *ref;
unsigned int hval = FRST (ip);
unsigned long off;
int lit = 0;
#if INIT_HTAB
# if USE_MEMCPY
memset (htab, 0, sizeof (htab));
# else
for (hslot = htab; hslot < htab + HSIZE; hslot++)
*hslot++ = ip;
# endif
#endif
do
{
hval = NEXT (hval, ip);
hslot = htab + IDX (hval);
ref = *hslot; *hslot = ip;
if (1
#if INIT_HTAB && !USE_MEMCPY
&& ref < ip /* the next test will actually take care of this, but it is faster */
#endif
&& (off = ip - ref - 1) < MAX_OFF
&& ip + 4 < in_end
&& ref > (u8 *)in_data
#if STRICT_ALIGN
&& ref[0] == ip[0]
&& ref[1] == ip[1]
&& ref[2] == ip[2]
#else
&& *(u16 *)ref == *(u16 *)ip
&& ref[2] == ip[2]
#endif
)
{
/* match found at *ref++ */
unsigned int len = 2;
unsigned int maxlen = in_end - ip - len;
maxlen = maxlen > MAX_REF ? MAX_REF : maxlen;
do
len++;
while (len < maxlen && ref[len] == ip[len]);
if (op + lit + 1 + 3 >= out_end)
return 0;
if (lit)
{
*op++ = lit - 1;
lit = -lit;
do
*op++ = ip[lit];
while (++lit);
}
len -= 2;
ip++;
if (len < 7)
{
*op++ = (off >> 8) + (len << 5);
}
else
{
*op++ = (off >> 8) + ( 7 << 5);
*op++ = len - 7;
}
*op++ = off;
#if ULTRA_FAST
ip += len;
hval = FRST (ip);
hval = NEXT (hval, ip);
htab[IDX (hval)] = ip;
ip++;
#else
do
{
hval = NEXT (hval, ip);
htab[IDX (hval)] = ip;
ip++;
}
while (len--);
#endif
}
else
{
/* one more literal byte we must copy */
lit++;
ip++;
if (lit == MAX_LIT)
{
if (op + 1 + MAX_LIT >= out_end)
return 0;
*op++ = MAX_LIT - 1;
#if USE_MEMCPY
memcpy (op, ip - MAX_LIT, MAX_LIT);
op += MAX_LIT;
lit = 0;
#else
lit = -lit;
do
*op++ = ip[lit];
while (++lit);
#endif
}
}
}
while (ip < in_end);
if (lit)
{
if (op + lit + 1 >= out_end)
return 0;
*op++ = lit - 1;
lit = -lit;
do
*op++ = ip[lit];
while (++lit);
}
return op - (u8 *) out_data;
}
|
