1 /*
2 * CDDL HEADER START
3 *
4 * The contents of this file are subject to the terms of the
5 * Common Development and Distribution License (the "License").
6 * You may not use this file except in compliance with the License.
7 *
8 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
9 * or http://www.opensolaris.org/os/licensing.
10 * See the License for the specific language governing permissions
11 * and limitations under the License.
12 *
13 * When distributing Covered Code, include this CDDL HEADER in each
14 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
15 * If applicable, add the following below this CDDL HEADER, with the
16 * fields enclosed by brackets "[]" replaced with your own identifying
17 * information: Portions Copyright [yyyy] [name of copyright owner]
18 *
19 * CDDL HEADER END
20 */
21
22 /*
23 * Copyright 2009 Sun Microsystems, Inc. All rights reserved.
24 * Use is subject to license terms.
25 */
26
27 /*
28 * Zero-length encoding. This is a fast and simple algorithm to eliminate
29 * runs of zeroes. Each chunk of compressed data begins with a length byte, b.
30 * If b < n (where n is the compression parameter) then the next b + 1 bytes
31 * are literal values. If b >= n then the next (256 - b + 1) bytes are zero.
32 */
33
34 static int
zle_decompress(void * s_start,void * d_start,size_t s_len,size_t d_len,int n)35 zle_decompress(void *s_start, void *d_start, size_t s_len, size_t d_len, int n)
36 {
37 unsigned char *src = s_start;
38 unsigned char *dst = d_start;
39 unsigned char *s_end = src + s_len;
40 unsigned char *d_end = dst + d_len;
41
42 while (src < s_end && dst < d_end) {
43 int len = 1 + *src++;
44 if (len <= n) {
45 while (len-- != 0)
46 *dst++ = *src++;
47 } else {
48 len -= n;
49 while (len-- != 0)
50 *dst++ = 0;
51 }
52 }
53 return (dst == d_end ? 0 : -1);
54 }
55