130 lines
3.8 KiB
C
130 lines
3.8 KiB
C
/*
|
|
* 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 2009 Sun Microsystems, Inc. All rights reserved.
|
|
* Use is subject to license terms.
|
|
*/
|
|
|
|
/*
|
|
* We keep our own copy of this algorithm for 2 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 return -1 if the data will not
|
|
* compress to d_len or less.
|
|
*/
|
|
|
|
#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*/
|
|
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_SLEEP);
|
|
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*/
|
|
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++;
|
|
}
|
|
}
|
|
return (0);
|
|
}
|