-
Notifications
You must be signed in to change notification settings - Fork 0
/
Copy pathlzjb.c
190 lines (171 loc) · 6.87 KB
/
lzjb.c
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
/*
* CDDL HEADER START
*
* The contents of this file are subject to the terms of the
* Common Development and Distribution License (the "License").
* You may not use this file except in compliance with the License.
*
* You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
* or http://www.opensolaris.org/os/licensing.
* See the License for the specific language governing permissions
* and limitations under the License.
*
* When distributing Covered Code, include this CDDL HEADER in each
* file and include the License file at usr/src/OPENSOLARIS.LICENSE.
* If applicable, add the following below this CDDL HEADER, with the
* fields enclosed by brackets "[]" replaced with your own identifying
* information: Portions Copyright [yyyy] [name of copyright owner]
*
* CDDL HEADER END
*/
/*
* Copyright (c) 2005, 2010, Oracle and/or its affiliates. All rights reserved.
*/
/*
* We keep our own copy of this algorithm for 3 main reasons:
* 1. If we didn't, anyone modifying common/os/compress.c would
* directly break our on disk format
* 2. Our version of lzjb does not have a number of checks that the
* common/os version needs and uses
* 3. We initialize the lempel to ensure deterministic results,
* so that identical blocks can always be deduplicated.
* In particular, we are adding the "feature" that compress() can
* take a destination buffer size and returns the compressed length, or the
* source length if compression would overflow the destination buffer.
*/
#include <sys/zfs_context.h>
#define MATCH_BITS 6
#define MATCH_MIN 3
#define MATCH_MAX ((1 << MATCH_BITS) + (MATCH_MIN - 1))
#define OFFSET_MASK ((1 << (16 - MATCH_BITS)) - 1)
#define LEMPEL_SIZE 1024
/*ARGSUSED*/
#ifdef KERN_DEOPT
size_t
lzjb_compress(void *s_start, void *d_start, size_t s_len, size_t d_len, int n)
__attribute__ ((__target__ ("no-mmx,no-sse")));
#endif
size_t
lzjb_compress(void *s_start, void *d_start, size_t s_len, size_t d_len, int n)
{
uchar_t *src = s_start;
uchar_t *dst = d_start;
uchar_t *cpy, *copymap = NULL;
int copymask = 1 << (NBBY - 1);
int mlen, offset, hash;
uint16_t *hp;
uint16_t *lempel;
lempel = kmem_zalloc(LEMPEL_SIZE * sizeof (uint16_t), KM_PUSHPAGE);
while (src < (uchar_t *)s_start + s_len) {
if ((copymask <<= 1) == (1 << NBBY)) {
if (dst >= (uchar_t *)d_start + d_len - 1 - 2 * NBBY) {
kmem_free(lempel, LEMPEL_SIZE*sizeof(uint16_t));
return (s_len);
}
copymask = 1;
copymap = dst;
*dst++ = 0;
}
if (src > (uchar_t *)s_start + s_len - MATCH_MAX) {
*dst++ = *src++;
continue;
}
hash = (src[0] << 16) + (src[1] << 8) + src[2];
hash += hash >> 9;
hash += hash >> 5;
hp = &lempel[hash & (LEMPEL_SIZE - 1)];
offset = (intptr_t)(src - *hp) & OFFSET_MASK;
*hp = (uint16_t)(uintptr_t)src;
cpy = src - offset;
if (cpy >= (uchar_t *)s_start && cpy != src &&
src[0] == cpy[0] && src[1] == cpy[1] && src[2] == cpy[2]) {
*copymap |= copymask;
for (mlen = MATCH_MIN; mlen < MATCH_MAX; mlen++)
if (src[mlen] != cpy[mlen])
break;
*dst++ = ((mlen - MATCH_MIN) << (NBBY - MATCH_BITS)) |
(offset >> NBBY);
*dst++ = (uchar_t)offset;
src += mlen;
} else {
*dst++ = *src++;
}
}
kmem_free(lempel, LEMPEL_SIZE * sizeof (uint16_t));
return (dst - (uchar_t *)d_start);
}
/*ARGSUSED*/
#ifdef KERN_DEOPT
int
lzjb_decompress(void *s_start, void *d_start, size_t s_len, size_t d_len, int n)
__attribute__ ((__target__ ("no-mmx,no-sse")));
#endif
int
lzjb_decompress(void *s_start, void *d_start, size_t s_len, size_t d_len, int n)
{
uchar_t *src = s_start;
uchar_t *dst = d_start;
uchar_t *d_end = (uchar_t *)d_start + d_len;
uchar_t *cpy, copymap = 0;
int copymask = 1 << (NBBY - 1);
while (dst < d_end) {
if ((copymask <<= 1) == (1 << NBBY)) {
copymask = 1;
copymap = *src++;
}
if (copymap & copymask) {
int mlen = (src[0] >> (NBBY - MATCH_BITS)) + MATCH_MIN;
int offset = ((src[0] << NBBY) | src[1]) & OFFSET_MASK;
src += 2;
if ((cpy = dst - offset) < (uchar_t *)d_start)
return (-1);
while (--mlen >= 0 && dst < d_end)
*dst++ = *cpy++;
} else {
*dst++ = *src++;
}
}
/* Test Code to check all source is used. NOT ZFS CODE */
if ((s_start + s_len) != src)
return ((void*)src-(void*)s_start);
return (0);
}
/*** Modified versions for testing are below here ***/
/*ARGSUSED*/
#ifdef KERN_DEOPT
int
lzjb_decompress_bsd(void *s_start, void *d_start, size_t s_len, size_t d_len, int n)
__attribute__ ((__target__ ("no-mmx,no-sse")));
#endif
int
lzjb_decompress_bsd(void *s_start, void *d_start, size_t s_len, size_t d_len, int n)
{
uchar_t *src = s_start;
uchar_t *dst = d_start;
uchar_t *d_end = (uchar_t *)d_start + d_len;
uchar_t *cpy, copymap = 0;
int copymask = 1 << (NBBY - 1);
while (dst < d_end) {
if ((copymask <<= 1) == (1 << NBBY)) {
copymask = 1;
copymap = *src++;
}
if (copymap & copymask) {
int mlen = (src[0] >> (NBBY - MATCH_BITS)) + MATCH_MIN;
int offset = ((src[0] << NBBY) | src[1]) & OFFSET_MASK;
src += 2;
if ((cpy = dst - offset) < (uchar_t *)d_start)
return (-1);
if (mlen > (d_end - dst))
mlen = d_end - dst;
while (--mlen >= 0)
*dst++ = *cpy++;
} else {
*dst++ = *src++;
}
}
/* Test Code to check all source is used. NOT ZFS CODE */
if ((s_start + s_len) != src)
return ((void*)src-(void*)s_start);
return (0);
}