/* * 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. */ /* * Zero-length encoding. This is a fast and simple algorithm to eliminate * runs of zeroes. Each chunk of compressed data begins with a length byte, b. * If b < n (where n is the compression parameter) then the next b + 1 bytes * are literal values. If b >= n then the next (256 - b + 1) bytes are zero. */ #include <sys/types.h> #include <sys/sysmacros.h> size_t zle_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 *s_end = src + s_len; uchar_t *d_end = dst + d_len; while (src < s_end && dst < d_end - 1) { uchar_t *first = src; uchar_t *len = dst++; if (src[0] == 0) { uchar_t *last = src + (256 - n); while (src < MIN(last, s_end) && src[0] == 0) src++; *len = src - first - 1 + n; } else { uchar_t *last = src + n; if (d_end - dst < n) break; while (src < MIN(last, s_end) - 1 && (src[0] | src[1])) *dst++ = *src++; if (src[0]) *dst++ = *src++; *len = src - first - 1; } } return (src == s_end ? dst - (uchar_t *)d_start : s_len); } int zle_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 *s_end = src + s_len; uchar_t *d_end = dst + d_len; while (src < s_end && dst < d_end) { int len = 1 + *src++; if (len <= n) { if (src + len > s_end || dst + len > d_end) return (-1); while (len-- != 0) *dst++ = *src++; } else { len -= n; if (dst + len > d_end) return (-1); while (len-- != 0) *dst++ = 0; } } return (dst == d_end ? 0 : -1); }