projects / mirror_zfs.git / blame
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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 | |
| 1d3ba0bf | 9 | * or https://opensource.org/licenses/CDDL-1.0. |
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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 | #include <sys/types.h> | |
| 34 | #include <sys/sysmacros.h> | |
| 60356b1a | 35 | #include <sys/zio_compress.h> |
| 428870ff BB |
36 | |
| 37 | size_t | |
| 38 | zle_compress(void *s_start, void *d_start, size_t s_len, size_t d_len, int n) | |
| 39 | { | |
| 40 | uchar_t *src = s_start; | |
| 41 | uchar_t *dst = d_start; | |
| 42 | uchar_t *s_end = src + s_len; | |
| 43 | uchar_t *d_end = dst + d_len; | |
| 44 | ||
| 45 | while (src < s_end && dst < d_end - 1) { | |
| 46 | uchar_t *first = src; | |
| 47 | uchar_t *len = dst++; | |
| 48 | if (src[0] == 0) { | |
| 49 | uchar_t *last = src + (256 - n); | |
| 50 | while (src < MIN(last, s_end) && src[0] == 0) | |
| 51 | src++; | |
| 52 | *len = src - first - 1 + n; | |
| 53 | } else { | |
| 54 | uchar_t *last = src + n; | |
| 55 | if (d_end - dst < n) | |
| 56 | break; | |
| 57 | while (src < MIN(last, s_end) - 1 && (src[0] | src[1])) | |
| 58 | *dst++ = *src++; | |
| 59 | if (src[0]) | |
| 60 | *dst++ = *src++; | |
| 61 | *len = src - first - 1; | |
| 62 | } | |
| 63 | } | |
| 64 | return (src == s_end ? dst - (uchar_t *)d_start : s_len); | |
| 65 | } | |
| 66 | ||
| 67 | int | |
| 68 | zle_decompress(void *s_start, void *d_start, size_t s_len, size_t d_len, int n) | |
| 69 | { | |
| 70 | uchar_t *src = s_start; | |
| 71 | uchar_t *dst = d_start; | |
| 72 | uchar_t *s_end = src + s_len; | |
| 73 | uchar_t *d_end = dst + d_len; | |
| 74 | ||
| 75 | while (src < s_end && dst < d_end) { | |
| 76 | int len = 1 + *src++; | |
| 77 | if (len <= n) { | |
| f108a492 CC |
78 | if (src + len > s_end || dst + len > d_end) |
| 79 | return (-1); | |
| 428870ff BB |
80 | while (len-- != 0) |
| 81 | *dst++ = *src++; | |
| 82 | } else { | |
| 83 | len -= n; | |
| f108a492 CC |
84 | if (dst + len > d_end) |
| 85 | return (-1); | |
| 428870ff BB |
86 | while (len-- != 0) |
| 87 | *dst++ = 0; | |
| 88 | } | |
| 89 | } | |
| 90 | return (dst == d_end ? 0 : -1); | |
| 91 | } |