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 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