1eda14cbcSMatt Macy /*
2eda14cbcSMatt Macy * CDDL HEADER START
3eda14cbcSMatt Macy *
4eda14cbcSMatt Macy * The contents of this file are subject to the terms of the
5eda14cbcSMatt Macy * Common Development and Distribution License (the "License").
6eda14cbcSMatt Macy * You may not use this file except in compliance with the License.
7eda14cbcSMatt Macy *
8eda14cbcSMatt Macy * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
9*271171e0SMartin Matuska * or https://opensource.org/licenses/CDDL-1.0.
10eda14cbcSMatt Macy * See the License for the specific language governing permissions
11eda14cbcSMatt Macy * and limitations under the License.
12eda14cbcSMatt Macy *
13eda14cbcSMatt Macy * When distributing Covered Code, include this CDDL HEADER in each
14eda14cbcSMatt Macy * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
15eda14cbcSMatt Macy * If applicable, add the following below this CDDL HEADER, with the
16eda14cbcSMatt Macy * fields enclosed by brackets "[]" replaced with your own identifying
17eda14cbcSMatt Macy * information: Portions Copyright [yyyy] [name of copyright owner]
18eda14cbcSMatt Macy *
19eda14cbcSMatt Macy * CDDL HEADER END
20eda14cbcSMatt Macy */
21eda14cbcSMatt Macy
22eda14cbcSMatt Macy /*
23eda14cbcSMatt Macy * Copyright (c) 2005, 2010, Oracle and/or its affiliates. All rights reserved.
24eda14cbcSMatt Macy */
25eda14cbcSMatt Macy
26eda14cbcSMatt Macy /*
27eda14cbcSMatt Macy * We keep our own copy of this algorithm for 3 main reasons:
28eda14cbcSMatt Macy * 1. If we didn't, anyone modifying common/os/compress.c would
29eda14cbcSMatt Macy * directly break our on disk format
30eda14cbcSMatt Macy * 2. Our version of lzjb does not have a number of checks that the
31eda14cbcSMatt Macy * common/os version needs and uses
32eda14cbcSMatt Macy * 3. We initialize the lempel to ensure deterministic results,
33eda14cbcSMatt Macy * so that identical blocks can always be deduplicated.
34eda14cbcSMatt Macy * In particular, we are adding the "feature" that compress() can
35eda14cbcSMatt Macy * take a destination buffer size and returns the compressed length, or the
36eda14cbcSMatt Macy * source length if compression would overflow the destination buffer.
37eda14cbcSMatt Macy */
38eda14cbcSMatt Macy
39eda14cbcSMatt Macy #include <sys/zfs_context.h>
40eda14cbcSMatt Macy #include <sys/zio_compress.h>
41eda14cbcSMatt Macy
42eda14cbcSMatt Macy #define MATCH_BITS 6
43eda14cbcSMatt Macy #define MATCH_MIN 3
44eda14cbcSMatt Macy #define MATCH_MAX ((1 << MATCH_BITS) + (MATCH_MIN - 1))
45eda14cbcSMatt Macy #define OFFSET_MASK ((1 << (16 - MATCH_BITS)) - 1)
46eda14cbcSMatt Macy #define LEMPEL_SIZE 1024
47eda14cbcSMatt Macy
48eda14cbcSMatt Macy size_t
lzjb_compress(void * s_start,void * d_start,size_t s_len,size_t d_len,int n)49eda14cbcSMatt Macy lzjb_compress(void *s_start, void *d_start, size_t s_len, size_t d_len, int n)
50eda14cbcSMatt Macy {
51e92ffd9bSMartin Matuska (void) n;
52eda14cbcSMatt Macy uchar_t *src = s_start;
53eda14cbcSMatt Macy uchar_t *dst = d_start;
54eda14cbcSMatt Macy uchar_t *cpy;
55eda14cbcSMatt Macy uchar_t *copymap = NULL;
56eda14cbcSMatt Macy int copymask = 1 << (NBBY - 1);
57eda14cbcSMatt Macy int mlen, offset, hash;
58eda14cbcSMatt Macy uint16_t *hp;
59eda14cbcSMatt Macy uint16_t *lempel;
60eda14cbcSMatt Macy
61eda14cbcSMatt Macy lempel = kmem_zalloc(LEMPEL_SIZE * sizeof (uint16_t), KM_SLEEP);
62eda14cbcSMatt Macy while (src < (uchar_t *)s_start + s_len) {
63eda14cbcSMatt Macy if ((copymask <<= 1) == (1 << NBBY)) {
64eda14cbcSMatt Macy if (dst >= (uchar_t *)d_start + d_len - 1 - 2 * NBBY) {
65eda14cbcSMatt Macy kmem_free(lempel,
66eda14cbcSMatt Macy LEMPEL_SIZE*sizeof (uint16_t));
67eda14cbcSMatt Macy return (s_len);
68eda14cbcSMatt Macy }
69eda14cbcSMatt Macy copymask = 1;
70eda14cbcSMatt Macy copymap = dst;
71eda14cbcSMatt Macy *dst++ = 0;
72eda14cbcSMatt Macy }
73eda14cbcSMatt Macy if (src > (uchar_t *)s_start + s_len - MATCH_MAX) {
74eda14cbcSMatt Macy *dst++ = *src++;
75eda14cbcSMatt Macy continue;
76eda14cbcSMatt Macy }
77eda14cbcSMatt Macy hash = (src[0] << 16) + (src[1] << 8) + src[2];
78eda14cbcSMatt Macy hash += hash >> 9;
79eda14cbcSMatt Macy hash += hash >> 5;
80eda14cbcSMatt Macy hp = &lempel[hash & (LEMPEL_SIZE - 1)];
81eda14cbcSMatt Macy offset = (intptr_t)(src - *hp) & OFFSET_MASK;
82eda14cbcSMatt Macy *hp = (uint16_t)(uintptr_t)src;
83eda14cbcSMatt Macy cpy = src - offset;
84eda14cbcSMatt Macy if (cpy >= (uchar_t *)s_start && cpy != src &&
85eda14cbcSMatt Macy src[0] == cpy[0] && src[1] == cpy[1] && src[2] == cpy[2]) {
86eda14cbcSMatt Macy *copymap |= copymask;
87eda14cbcSMatt Macy for (mlen = MATCH_MIN; mlen < MATCH_MAX; mlen++)
88eda14cbcSMatt Macy if (src[mlen] != cpy[mlen])
89eda14cbcSMatt Macy break;
90eda14cbcSMatt Macy *dst++ = ((mlen - MATCH_MIN) << (NBBY - MATCH_BITS)) |
91eda14cbcSMatt Macy (offset >> NBBY);
92eda14cbcSMatt Macy *dst++ = (uchar_t)offset;
93eda14cbcSMatt Macy src += mlen;
94eda14cbcSMatt Macy } else {
95eda14cbcSMatt Macy *dst++ = *src++;
96eda14cbcSMatt Macy }
97eda14cbcSMatt Macy }
98eda14cbcSMatt Macy
99eda14cbcSMatt Macy kmem_free(lempel, LEMPEL_SIZE * sizeof (uint16_t));
100eda14cbcSMatt Macy return (dst - (uchar_t *)d_start);
101eda14cbcSMatt Macy }
102eda14cbcSMatt Macy
103eda14cbcSMatt Macy int
lzjb_decompress(void * s_start,void * d_start,size_t s_len,size_t d_len,int n)104eda14cbcSMatt Macy lzjb_decompress(void *s_start, void *d_start, size_t s_len, size_t d_len, int n)
105eda14cbcSMatt Macy {
106e92ffd9bSMartin Matuska (void) s_len, (void) n;
107eda14cbcSMatt Macy uchar_t *src = s_start;
108eda14cbcSMatt Macy uchar_t *dst = d_start;
109eda14cbcSMatt Macy uchar_t *d_end = (uchar_t *)d_start + d_len;
110eda14cbcSMatt Macy uchar_t *cpy;
111eda14cbcSMatt Macy uchar_t copymap = 0;
112eda14cbcSMatt Macy int copymask = 1 << (NBBY - 1);
113eda14cbcSMatt Macy
114eda14cbcSMatt Macy while (dst < d_end) {
115eda14cbcSMatt Macy if ((copymask <<= 1) == (1 << NBBY)) {
116eda14cbcSMatt Macy copymask = 1;
117eda14cbcSMatt Macy copymap = *src++;
118eda14cbcSMatt Macy }
119eda14cbcSMatt Macy if (copymap & copymask) {
120eda14cbcSMatt Macy int mlen = (src[0] >> (NBBY - MATCH_BITS)) + MATCH_MIN;
121eda14cbcSMatt Macy int offset = ((src[0] << NBBY) | src[1]) & OFFSET_MASK;
122eda14cbcSMatt Macy src += 2;
123eda14cbcSMatt Macy if ((cpy = dst - offset) < (uchar_t *)d_start)
124eda14cbcSMatt Macy return (-1);
125eda14cbcSMatt Macy while (--mlen >= 0 && dst < d_end)
126eda14cbcSMatt Macy *dst++ = *cpy++;
127eda14cbcSMatt Macy } else {
128eda14cbcSMatt Macy *dst++ = *src++;
129eda14cbcSMatt Macy }
130eda14cbcSMatt Macy }
131eda14cbcSMatt Macy return (0);
132eda14cbcSMatt Macy }
133