1 | /*␊ |
2 | * Copyright (c) 2003 Apple Computer, Inc. All rights reserved.␊ |
3 | *␊ |
4 | * @APPLE_LICENSE_HEADER_START@␊ |
5 | * ␊ |
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.␊ |
13 | * ␊ |
14 | * The Original Code and all software distributed under the License are␊ |
15 | * distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY KIND, EITHER␊ |
16 | * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,␊ |
17 | * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,␊ |
18 | * FITNESS FOR A PARTICULAR PURPOSE OR NON- INFRINGEMENT. Please see the␊ |
19 | * License for the specific language governing rights and limitations␊ |
20 | * under the License.␊ |
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 N_MIN_1␉␉4095␊ |
47 | #define F␉␉18␉/* Upper limit for match_length. */␊ |
48 | #define R␉␉N - F␊ |
49 | #define THRESHOLD␉2␉/* Encode string into position and length if match_length is greater than this. */␊ |
50 | #define NIL␉␉N␉/* Index for root of binary search trees. */␊ |
51 | ␊ |
52 | ␊ |
53 | //==============================================================================␊ |
54 | // Refactoring and bug fix Copyright (c) 2010 by DHP.␊ |
55 | ␊ |
56 | int decompress_lzss(u_int8_t * dst, u_int8_t * src, u_int32_t srclen)␊ |
57 | {␊ |
58 | ␉/* Four KB ring buffer with 17 extra bytes added to aid string comparisons. */␊ |
59 | ␉u_int8_t text_buf[N_MIN_1 + F];␊ |
60 | ␉u_int8_t * dststart = dst;␊ |
61 | ␉const u_int8_t * srcend = (src + srclen);␊ |
62 | ␊ |
63 | ␉int r = R;␊ |
64 | ␉int i, j, k, c;␊ |
65 | ␉unsigned int flags = 0;␊ |
66 | ␊ |
67 | ␉for (i = 0; i < R; i++)␊ |
68 | ␉{␊ |
69 | ␉␉text_buf[i] = ' ';␊ |
70 | ␉}␊ |
71 | ␊ |
72 | ␉while (src < srcend)␊ |
73 | ␉{␊ |
74 | ␉␉if (((flags >>= 1) & 0x100) == 0)␊ |
75 | ␉␉{␊ |
76 | ␉␉␉c = *src++;␊ |
77 | ␉␉␉flags = c | 0xFF00; // Clever use of the high byte.␊ |
78 | ␉}␊ |
79 | ␊ |
80 | ␉if ((src < srcend) && (flags & 1))␊ |
81 | ␉␉{␊ |
82 | ␉␉␉c = *src++;␊ |
83 | ␉␉␉*dst++ = c;␊ |
84 | ␉␉␉text_buf[r++] = c;␊ |
85 | ␉␉␉r &= N_MIN_1;␊ |
86 | ␉␉}␊ |
87 | ␉␉else if ((src + 2) <= srcend)␊ |
88 | ␉␉{␊ |
89 | ␉␉␉i = *src++;␊ |
90 | ␉␉␉j = *src++;␊ |
91 | ␊ |
92 | ␉␉␉i |= ((j & 0xF0) << 4);␊ |
93 | ␉␉␉j = (j & 0x0F) + THRESHOLD;␊ |
94 | ␊ |
95 | ␉␉␉for (k = 0; k <= j; k++)␊ |
96 | ␉␉␉{␊ |
97 | ␉␉␉␉c = text_buf[(i + k) & N_MIN_1];␊ |
98 | ␉␉␉␉*dst++ = c;␊ |
99 | ␉␉␉␉text_buf[r++] = c;␊ |
100 | ␉␉␉␉r &= N_MIN_1;␊ |
101 | ␉␉␉}␊ |
102 | ␉␉}␊ |
103 | ␉}␊ |
104 | ␊ |
105 | ␉return dst - dststart;␊ |
106 | }␊ |
107 | |