| 1 | /*␊ |
| 2 | * Copyright (c) 2003 Apple Computer, Inc. All rights reserved.␊ |
| 3 | *␊ |
| 4 | * ␊ |
| 5 | * Portions Copyright (c) 1999-2003 Apple Computer, Inc. All Rights␊ |
| 6 | * Reserved. This file contains Original Code and/or Modifications of␊ |
| 7 | * Original Code as defined in and that are subject to the Apple Public␊ |
| 8 | * Source License Version 2.0 (the "License"). You may not use this file␊ |
| 9 | * except in compliance with the License. Please obtain a copy of the␊ |
| 10 | * License at http://www.apple.com/publicsource and read it before using␊ |
| 11 | * this file.␊ |
| 12 | * ␊ |
| 13 | * The Original Code and all software distributed under the License are␊ |
| 14 | * distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY KIND, EITHER␊ |
| 15 | * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,␊ |
| 16 | * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,␊ |
| 17 | * FITNESS FOR A PARTICULAR PURPOSE OR NON- INFRINGEMENT. Please see the␊ |
| 18 | * License for the specific language governing rights and limitations␊ |
| 19 | * under the License.␊ |
| 20 | * ␊ |
| 21 | *␊ |
| 22 | ***************************************************************␊ |
| 23 | LZSS.C -- A Data Compression Program␊ |
| 24 | ***************************************************************␊ |
| 25 | 4/6/1989 Haruhiko Okumura␊ |
| 26 | Use, distribute, and modify this program freely.␊ |
| 27 | Please send me your improved versions.␊ |
| 28 | PC-VAN SCIENCE␊ |
| 29 | NIFTY-Serve PAF01022␊ |
| 30 | CompuServe 74050,1022␊ |
| 31 | ␊ |
| 32 | **************************************************************+␊ |
| 33 | *␊ |
| 34 | * lzss.c - Package for decompressing lzss compressed objects␊ |
| 35 | *␊ |
| 36 | * Copyright (c) 2003 Apple Computer, Inc.␊ |
| 37 | *␊ |
| 38 | * DRI: Josh de Cesare␊ |
| 39 | */␊ |
| 40 | ␊ |
| 41 | #include <sl.h>␊ |
| 42 | ␊ |
| 43 | #define N␉␉4096␉/* Size of ring buffer - must be power of 2. */␊ |
| 44 | #define N_MIN_1␉␉4095␊ |
| 45 | #define F␉␉18␉/* Upper limit for match_length. */␊ |
| 46 | #define R␉␉N - F␊ |
| 47 | #define THRESHOLD␉2␉/* Encode string into position and length if match_length is greater than this. */␊ |
| 48 | #define NIL␉␉N␉/* Index for root of binary search trees. */␊ |
| 49 | ␊ |
| 50 | ␊ |
| 51 | //==============================================================================␊ |
| 52 | // Refactoring and bug fix Copyright (c) 2010 by DHP.␊ |
| 53 | ␊ |
| 54 | int decompress_lzss(u_int8_t * dst, u_int8_t * src, u_int32_t srclen)␊ |
| 55 | {␊ |
| 56 | ␉/* Four KB ring buffer with 17 extra bytes added to aid string comparisons. */␊ |
| 57 | ␉u_int8_t text_buf[N_MIN_1 + F];␊ |
| 58 | ␉u_int8_t * dststart = dst;␊ |
| 59 | ␉const u_int8_t * srcend = (src + srclen);␊ |
| 60 | ␊ |
| 61 | ␉int r = R;␊ |
| 62 | ␉int i, j, k, c;␊ |
| 63 | ␉unsigned int flags = 0;␊ |
| 64 | ␊ |
| 65 | ␉for (i = 0; i < R; i++)␊ |
| 66 | ␉{␊ |
| 67 | ␉␉text_buf[i] = ' ';␊ |
| 68 | ␉}␊ |
| 69 | ␊ |
| 70 | ␉while (src < srcend)␊ |
| 71 | ␉{␊ |
| 72 | ␉␉if (((flags >>= 1) & 0x100) == 0)␊ |
| 73 | ␉␉{␊ |
| 74 | ␉␉␉c = *src++;␊ |
| 75 | ␉␉␉flags = c | 0xFF00; // Clever use of the high byte.␊ |
| 76 | ␉}␊ |
| 77 | ␊ |
| 78 | ␉if ((src < srcend) && (flags & 1))␊ |
| 79 | ␉␉{␊ |
| 80 | ␉␉␉c = *src++;␊ |
| 81 | ␉␉␉*dst++ = c;␊ |
| 82 | ␉␉␉text_buf[r++] = c;␊ |
| 83 | ␉␉␉r &= N_MIN_1;␊ |
| 84 | ␉␉}␊ |
| 85 | ␉␉else if ((src + 2) <= srcend)␊ |
| 86 | ␉␉{␊ |
| 87 | ␉␉␉i = *src++;␊ |
| 88 | ␉␉␉j = *src++;␊ |
| 89 | ␊ |
| 90 | ␉␉␉i |= ((j & 0xF0) << 4);␊ |
| 91 | ␉␉␉j = (j & 0x0F) + THRESHOLD;␊ |
| 92 | ␊ |
| 93 | ␉␉␉for (k = 0; k <= j; k++)␊ |
| 94 | ␉␉␉{␊ |
| 95 | ␉␉␉␉c = text_buf[(i + k) & N_MIN_1];␊ |
| 96 | ␉␉␉␉*dst++ = c;␊ |
| 97 | ␉␉␉␉text_buf[r++] = c;␊ |
| 98 | ␉␉␉␉r &= N_MIN_1;␊ |
| 99 | ␉␉␉}␊ |
| 100 | ␉␉}␊ |
| 101 | ␉}␊ |
| 102 | ␊ |
| 103 | ␉return dst - dststart;␊ |
| 104 | }␊ |
| 105 | |
