diff options
Diffstat (limited to 'sys/cddl/boot/zfs/lzjb.c')
-rw-r--r-- | sys/cddl/boot/zfs/lzjb.c | 74 |
1 files changed, 74 insertions, 0 deletions
diff --git a/sys/cddl/boot/zfs/lzjb.c b/sys/cddl/boot/zfs/lzjb.c new file mode 100644 index 000000000000..1283a6c31a4b --- /dev/null +++ b/sys/cddl/boot/zfs/lzjb.c @@ -0,0 +1,74 @@ +/* + * 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 2007 Sun Microsystems, Inc. All rights reserved. + * Use is subject to license terms. + */ + +/*#pragma ident "%Z%%M% %I% %E% SMI"*/ + +/* + * 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 + * 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. + */ + +#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 256 + +/*ARGSUSED*/ +static int +lzjb_decompress(void *s_start, void *d_start, size_t s_len, size_t d_len, int n) +{ + unsigned char *src = s_start; + unsigned char *dst = d_start; + unsigned char *d_end = (unsigned char *)d_start + d_len; + unsigned char *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) < (unsigned char *)d_start) + return (-1); + while (--mlen >= 0 && dst < d_end) + *dst++ = *cpy++; + } else { + *dst++ = *src++; + } + } + return (0); +} |