projects / apple / boot.git / blame
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|---|---|---|
| f083c6c3 A |
1 | /* |
| 2 | * Copyright (c) 2003 Apple Computer, Inc. All rights reserved. | |
| 3 | * | |
| 4 | * @APPLE_LICENSE_HEADER_START@ | |
| 5 | * | |
| 57c72a9a A |
6 | * Portions Copyright (c) 1999-2003 Apple Computer, Inc. All Rights |
| 7 | * Reserved. This file contains Original Code and/or Modifications of | |
| 8 | * Original Code as defined in and that are subject to the Apple Public | |
| 9 | * Source License Version 2.0 (the "License"). You may not use this file | |
| 10 | * except in compliance with the License. Please obtain a copy of the | |
| 11 | * License at http://www.apple.com/publicsource and read it before using | |
| 12 | * this file. | |
| f083c6c3 | 13 | * |
| 57c72a9a | 14 | * The Original Code and all software distributed under the License are |
| 4f6e3300 | 15 | * distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY KIND, EITHER |
| f083c6c3 A |
16 | * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES, |
| 17 | * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY, | |
| 57c72a9a | 18 | * FITNESS FOR A PARTICULAR PURPOSE OR NON- INFRINGEMENT. Please see the |
| 4f6e3300 A |
19 | * License for the specific language governing rights and limitations |
| 20 | * under the License. | |
| f083c6c3 A |
21 | * |
| 22 | * @APPLE_LICENSE_HEADER_END@ | |
| 23 | */ | |
| 24 | /************************************************************** | |
| 25 | LZSS.C -- A Data Compression Program | |
| 26 | *************************************************************** | |
| 27 | 4/6/1989 Haruhiko Okumura | |
| 28 | Use, distribute, and modify this program freely. | |
| 29 | Please send me your improved versions. | |
| 30 | PC-VAN SCIENCE | |
| 31 | NIFTY-Serve PAF01022 | |
| 32 | CompuServe 74050,1022 | |
| 33 | ||
| 34 | **************************************************************/ | |
| 35 | /* | |
| 36 | * lzss.c - Package for decompressing lzss compressed objects | |
| 37 | * | |
| 38 | * Copyright (c) 2003 Apple Computer, Inc. | |
| 39 | * | |
| 40 | * DRI: Josh de Cesare | |
| 41 | */ | |
| 42 | ||
| 43 | #include <sl.h> | |
| 44 | ||
| 45 | #define N 4096 /* size of ring buffer - must be power of 2 */ | |
| 46 | #define F 18 /* upper limit for match_length */ | |
| 47 | #define THRESHOLD 2 /* encode string into position and length | |
| 48 | if match_length is greater than this */ | |
| 49 | #define NIL N /* index for root of binary search trees */ | |
| 50 | ||
| 51 | int | |
| 52 | decompress_lzss(u_int8_t *dst, u_int8_t *src, u_int32_t srclen) | |
| 53 | { | |
| 54 | /* ring buffer of size N, with extra F-1 bytes to aid string comparison */ | |
| 55 | u_int8_t text_buf[N + F - 1]; | |
| 56 | u_int8_t *dststart = dst; | |
| 57 | u_int8_t *srcend = src + srclen; | |
| 58 | int i, j, k, r, c; | |
| 59 | unsigned int flags; | |
| 60 | ||
| 61 | dst = dststart; | |
| 62 | srcend = src + srclen; | |
| 63 | for (i = 0; i < N - F; i++) | |
| 64 | text_buf[i] = ' '; | |
| 65 | r = N - F; | |
| 66 | flags = 0; | |
| 67 | for ( ; ; ) { | |
| 68 | if (((flags >>= 1) & 0x100) == 0) { | |
| 69 | if (src < srcend) c = *src++; else break; | |
| 70 | flags = c | 0xFF00; /* uses higher byte cleverly */ | |
| 71 | } /* to count eight */ | |
| 72 | if (flags & 1) { | |
| 73 | if (src < srcend) c = *src++; else break; | |
| 74 | *dst++ = c; | |
| 75 | text_buf[r++] = c; | |
| 76 | r &= (N - 1); | |
| 77 | } else { | |
| 78 | if (src < srcend) i = *src++; else break; | |
| 79 | if (src < srcend) j = *src++; else break; | |
| 80 | i |= ((j & 0xF0) << 4); | |
| 81 | j = (j & 0x0F) + THRESHOLD; | |
| 82 | for (k = 0; k <= j; k++) { | |
| 83 | c = text_buf[(i + k) & (N - 1)]; | |
| 84 | *dst++ = c; | |
| 85 | text_buf[r++] = c; | |
| 86 | r &= (N - 1); | |
| 87 | } | |
| 88 | } | |
| 89 | } | |
| 90 | ||
| 91 | return dst - dststart; | |
| 92 | } |