1*b24ab676SJeff Bonwick /* 2*b24ab676SJeff Bonwick * CDDL HEADER START 3*b24ab676SJeff Bonwick * 4*b24ab676SJeff Bonwick * The contents of this file are subject to the terms of the 5*b24ab676SJeff Bonwick * Common Development and Distribution License (the "License"). 6*b24ab676SJeff Bonwick * You may not use this file except in compliance with the License. 7*b24ab676SJeff Bonwick * 8*b24ab676SJeff Bonwick * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE 9*b24ab676SJeff Bonwick * or http://www.opensolaris.org/os/licensing. 10*b24ab676SJeff Bonwick * See the License for the specific language governing permissions 11*b24ab676SJeff Bonwick * and limitations under the License. 12*b24ab676SJeff Bonwick * 13*b24ab676SJeff Bonwick * When distributing Covered Code, include this CDDL HEADER in each 14*b24ab676SJeff Bonwick * file and include the License file at usr/src/OPENSOLARIS.LICENSE. 15*b24ab676SJeff Bonwick * If applicable, add the following below this CDDL HEADER, with the 16*b24ab676SJeff Bonwick * fields enclosed by brackets "[]" replaced with your own identifying 17*b24ab676SJeff Bonwick * information: Portions Copyright [yyyy] [name of copyright owner] 18*b24ab676SJeff Bonwick * 19*b24ab676SJeff Bonwick * CDDL HEADER END 20*b24ab676SJeff Bonwick */ 21*b24ab676SJeff Bonwick 22*b24ab676SJeff Bonwick /* 23*b24ab676SJeff Bonwick * Copyright 2009 Sun Microsystems, Inc. All rights reserved. 24*b24ab676SJeff Bonwick * Use is subject to license terms. 25*b24ab676SJeff Bonwick */ 26*b24ab676SJeff Bonwick 27*b24ab676SJeff Bonwick /* 28*b24ab676SJeff Bonwick * Zero-length encoding. This is a fast and simple algorithm to eliminate 29*b24ab676SJeff Bonwick * runs of zeroes. Each chunk of compressed data begins with a length byte, b. 30*b24ab676SJeff Bonwick * If b < n (where n is the compression parameter) then the next b + 1 bytes 31*b24ab676SJeff Bonwick * are literal values. If b >= n then the next (256 - b + 1) bytes are zero. 32*b24ab676SJeff Bonwick */ 33*b24ab676SJeff Bonwick #include <sys/types.h> 34*b24ab676SJeff Bonwick #include <sys/sysmacros.h> 35*b24ab676SJeff Bonwick 36*b24ab676SJeff Bonwick size_t 37*b24ab676SJeff Bonwick zle_compress(void *s_start, void *d_start, size_t s_len, size_t d_len, int n) 38*b24ab676SJeff Bonwick { 39*b24ab676SJeff Bonwick uchar_t *src = s_start; 40*b24ab676SJeff Bonwick uchar_t *dst = d_start; 41*b24ab676SJeff Bonwick uchar_t *s_end = src + s_len; 42*b24ab676SJeff Bonwick uchar_t *d_end = dst + d_len; 43*b24ab676SJeff Bonwick 44*b24ab676SJeff Bonwick while (src < s_end && dst < d_end - 1) { 45*b24ab676SJeff Bonwick uchar_t *first = src; 46*b24ab676SJeff Bonwick uchar_t *len = dst++; 47*b24ab676SJeff Bonwick if (src[0] == 0) { 48*b24ab676SJeff Bonwick uchar_t *last = src + (256 - n); 49*b24ab676SJeff Bonwick while (src < MIN(last, s_end) && src[0] == 0) 50*b24ab676SJeff Bonwick src++; 51*b24ab676SJeff Bonwick *len = src - first - 1 + n; 52*b24ab676SJeff Bonwick } else { 53*b24ab676SJeff Bonwick uchar_t *last = src + n; 54*b24ab676SJeff Bonwick if (d_end - dst < n) 55*b24ab676SJeff Bonwick break; 56*b24ab676SJeff Bonwick while (src < MIN(last, s_end) - 1 && (src[0] | src[1])) 57*b24ab676SJeff Bonwick *dst++ = *src++; 58*b24ab676SJeff Bonwick if (src[0]) 59*b24ab676SJeff Bonwick *dst++ = *src++; 60*b24ab676SJeff Bonwick *len = src - first - 1; 61*b24ab676SJeff Bonwick } 62*b24ab676SJeff Bonwick } 63*b24ab676SJeff Bonwick return (src == s_end ? dst - (uchar_t *)d_start : s_len); 64*b24ab676SJeff Bonwick } 65*b24ab676SJeff Bonwick 66*b24ab676SJeff Bonwick int 67*b24ab676SJeff Bonwick zle_decompress(void *s_start, void *d_start, size_t s_len, size_t d_len, int n) 68*b24ab676SJeff Bonwick { 69*b24ab676SJeff Bonwick uchar_t *src = s_start; 70*b24ab676SJeff Bonwick uchar_t *dst = d_start; 71*b24ab676SJeff Bonwick uchar_t *s_end = src + s_len; 72*b24ab676SJeff Bonwick uchar_t *d_end = dst + d_len; 73*b24ab676SJeff Bonwick 74*b24ab676SJeff Bonwick while (src < s_end && dst < d_end) { 75*b24ab676SJeff Bonwick int len = 1 + *src++; 76*b24ab676SJeff Bonwick if (len <= n) { 77*b24ab676SJeff Bonwick while (len-- != 0) 78*b24ab676SJeff Bonwick *dst++ = *src++; 79*b24ab676SJeff Bonwick } else { 80*b24ab676SJeff Bonwick len -= n; 81*b24ab676SJeff Bonwick while (len-- != 0) 82*b24ab676SJeff Bonwick *dst++ = 0; 83*b24ab676SJeff Bonwick } 84*b24ab676SJeff Bonwick } 85*b24ab676SJeff Bonwick return (dst == d_end ? 0 : -1); 86*b24ab676SJeff Bonwick } 87