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author | Jacek Antonelli | 2008-08-15 23:44:46 -0500 |
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committer | Jacek Antonelli | 2008-08-15 23:44:46 -0500 |
commit | 38d6d37f2d982fa959e9e8a4a3f7e1ccfad7b5d4 (patch) | |
tree | adca584755d22ca041a2dbfc35d4eca01f70b32c /linden/indra/llmath/llcrc.cpp | |
parent | README.txt (diff) | |
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Second Life viewer sources 1.13.2.12
Diffstat (limited to 'linden/indra/llmath/llcrc.cpp')
-rw-r--r-- | linden/indra/llmath/llcrc.cpp | 206 |
1 files changed, 206 insertions, 0 deletions
diff --git a/linden/indra/llmath/llcrc.cpp b/linden/indra/llmath/llcrc.cpp new file mode 100644 index 0000000..4194432 --- /dev/null +++ b/linden/indra/llmath/llcrc.cpp | |||
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1 | /** | ||
2 | * @file llcrc.cpp | ||
3 | * @brief implementation of the crc class. | ||
4 | * | ||
5 | * Copyright (c) 2002-2007, Linden Research, Inc. | ||
6 | * | ||
7 | * The source code in this file ("Source Code") is provided by Linden Lab | ||
8 | * to you under the terms of the GNU General Public License, version 2.0 | ||
9 | * ("GPL"), unless you have obtained a separate licensing agreement | ||
10 | * ("Other License"), formally executed by you and Linden Lab. Terms of | ||
11 | * the GPL can be found in doc/GPL-license.txt in this distribution, or | ||
12 | * online at http://secondlife.com/developers/opensource/gplv2 | ||
13 | * | ||
14 | * There are special exceptions to the terms and conditions of the GPL as | ||
15 | * it is applied to this Source Code. View the full text of the exception | ||
16 | * in the file doc/FLOSS-exception.txt in this software distribution, or | ||
17 | * online at http://secondlife.com/developers/opensource/flossexception | ||
18 | * | ||
19 | * By copying, modifying or distributing this software, you acknowledge | ||
20 | * that you have read and understood your obligations described above, | ||
21 | * and agree to abide by those obligations. | ||
22 | * | ||
23 | * ALL LINDEN LAB SOURCE CODE IS PROVIDED "AS IS." LINDEN LAB MAKES NO | ||
24 | * WARRANTIES, EXPRESS, IMPLIED OR OTHERWISE, REGARDING ITS ACCURACY, | ||
25 | * COMPLETENESS OR PERFORMANCE. | ||
26 | */ | ||
27 | |||
28 | #include "linden_common.h" | ||
29 | |||
30 | #include "llcrc.h" | ||
31 | #include "llerror.h" | ||
32 | |||
33 | #include <stdio.h> | ||
34 | |||
35 | /* Copyright (C) 1986 Gary S. Brown. You may use this program, or | ||
36 | code or tables extracted from it, as desired without restriction.*/ | ||
37 | |||
38 | /* First, the polynomial itself and its table of feedback terms. The */ | ||
39 | /* polynomial is */ | ||
40 | /* X^32+X^26+X^23+X^22+X^16+X^12+X^11+X^10+X^8+X^7+X^5+X^4+X^2+X^1+X^0 */ | ||
41 | /* Note that we take it "backwards" and put the highest-order term in */ | ||
42 | /* the lowest-order bit. The X^32 term is "implied"; the LSB is the */ | ||
43 | /* X^31 term, etc. The X^0 term (usually shown as "+1") results in */ | ||
44 | /* the MSB being 1. */ | ||
45 | |||
46 | /* Note that the usual hardware shift register implementation, which */ | ||
47 | /* is what we're using (we're merely optimizing it by doing eight-bit */ | ||
48 | /* chunks at a time) shifts bits into the lowest-order term. In our */ | ||
49 | /* implementation, that means shifting towards the right. Why do we */ | ||
50 | /* do it this way? Because the calculated CRC must be transmitted in */ | ||
51 | /* order from highest-order term to lowest-order term. UARTs transmit */ | ||
52 | /* characters in order from LSB to MSB. By storing the CRC this way, */ | ||
53 | /* we hand it to the UART in the order low-byte to high-byte; the UART */ | ||
54 | /* sends each low-bit to hight-bit; and the result is transmission bit */ | ||
55 | /* by bit from highest- to lowest-order term without requiring any bit */ | ||
56 | /* shuffling on our part. Reception works similarly. */ | ||
57 | |||
58 | /* The feedback terms table consists of 256, 32-bit entries. Notes: */ | ||
59 | /* */ | ||
60 | /* 1. The table can be generated at runtime if desired; code to do so */ | ||
61 | /* is shown later. It might not be obvious, but the feedback */ | ||
62 | /* terms simply represent the results of eight shift/xor opera- */ | ||
63 | /* tions for all combinations of data and CRC register values. */ | ||
64 | /* */ | ||
65 | /* 2. The CRC accumulation logic is the same for all CRC polynomials, */ | ||
66 | /* be they sixteen or thirty-two bits wide. You simply choose the */ | ||
67 | /* appropriate table. Alternatively, because the table can be */ | ||
68 | /* generated at runtime, you can start by generating the table for */ | ||
69 | /* the polynomial in question and use exactly the same "updcrc", */ | ||
70 | /* if your application needn't simultaneously handle two CRC */ | ||
71 | /* polynomials. (Note, however, that XMODEM is strange.) */ | ||
72 | /* */ | ||
73 | /* 3. For 16-bit CRCs, the table entries need be only 16 bits wide; */ | ||
74 | /* of course, 32-bit entries work OK if the high 16 bits are zero. */ | ||
75 | /* */ | ||
76 | /* 4. The values must be right-shifted by eight bits by the "updcrc" */ | ||
77 | /* logic; the shift must be unsigned (bring in zeroes). On some */ | ||
78 | /* hardware you could probably optimize the shift in assembler by */ | ||
79 | /* using byte-swap instructions. */ | ||
80 | |||
81 | ///---------------------------------------------------------------------------- | ||
82 | /// Local function declarations, constants, enums, and typedefs | ||
83 | ///---------------------------------------------------------------------------- | ||
84 | |||
85 | #define UPDC32(octet,crc) (crc_32_tab[((crc) \ | ||
86 | ^ ((U8)octet)) & 0xff] ^ ((crc) >> 8)) | ||
87 | |||
88 | |||
89 | static U32 crc_32_tab[] = { /* CRC polynomial 0xedb88320 */ | ||
90 | 0x00000000, 0x77073096, 0xee0e612c, 0x990951ba, 0x076dc419, 0x706af48f, | ||
91 | 0xe963a535, 0x9e6495a3, 0x0edb8832, 0x79dcb8a4, 0xe0d5e91e, 0x97d2d988, | ||
92 | 0x09b64c2b, 0x7eb17cbd, 0xe7b82d07, 0x90bf1d91, 0x1db71064, 0x6ab020f2, | ||
93 | 0xf3b97148, 0x84be41de, 0x1adad47d, 0x6ddde4eb, 0xf4d4b551, 0x83d385c7, | ||
94 | 0x136c9856, 0x646ba8c0, 0xfd62f97a, 0x8a65c9ec, 0x14015c4f, 0x63066cd9, | ||
95 | 0xfa0f3d63, 0x8d080df5, 0x3b6e20c8, 0x4c69105e, 0xd56041e4, 0xa2677172, | ||
96 | 0x3c03e4d1, 0x4b04d447, 0xd20d85fd, 0xa50ab56b, 0x35b5a8fa, 0x42b2986c, | ||
97 | 0xdbbbc9d6, 0xacbcf940, 0x32d86ce3, 0x45df5c75, 0xdcd60dcf, 0xabd13d59, | ||
98 | 0x26d930ac, 0x51de003a, 0xc8d75180, 0xbfd06116, 0x21b4f4b5, 0x56b3c423, | ||
99 | 0xcfba9599, 0xb8bda50f, 0x2802b89e, 0x5f058808, 0xc60cd9b2, 0xb10be924, | ||
100 | 0x2f6f7c87, 0x58684c11, 0xc1611dab, 0xb6662d3d, 0x76dc4190, 0x01db7106, | ||
101 | 0x98d220bc, 0xefd5102a, 0x71b18589, 0x06b6b51f, 0x9fbfe4a5, 0xe8b8d433, | ||
102 | 0x7807c9a2, 0x0f00f934, 0x9609a88e, 0xe10e9818, 0x7f6a0dbb, 0x086d3d2d, | ||
103 | 0x91646c97, 0xe6635c01, 0x6b6b51f4, 0x1c6c6162, 0x856530d8, 0xf262004e, | ||
104 | 0x6c0695ed, 0x1b01a57b, 0x8208f4c1, 0xf50fc457, 0x65b0d9c6, 0x12b7e950, | ||
105 | 0x8bbeb8ea, 0xfcb9887c, 0x62dd1ddf, 0x15da2d49, 0x8cd37cf3, 0xfbd44c65, | ||
106 | 0x4db26158, 0x3ab551ce, 0xa3bc0074, 0xd4bb30e2, 0x4adfa541, 0x3dd895d7, | ||
107 | 0xa4d1c46d, 0xd3d6f4fb, 0x4369e96a, 0x346ed9fc, 0xad678846, 0xda60b8d0, | ||
108 | 0x44042d73, 0x33031de5, 0xaa0a4c5f, 0xdd0d7cc9, 0x5005713c, 0x270241aa, | ||
109 | 0xbe0b1010, 0xc90c2086, 0x5768b525, 0x206f85b3, 0xb966d409, 0xce61e49f, | ||
110 | 0x5edef90e, 0x29d9c998, 0xb0d09822, 0xc7d7a8b4, 0x59b33d17, 0x2eb40d81, | ||
111 | 0xb7bd5c3b, 0xc0ba6cad, 0xedb88320, 0x9abfb3b6, 0x03b6e20c, 0x74b1d29a, | ||
112 | 0xead54739, 0x9dd277af, 0x04db2615, 0x73dc1683, 0xe3630b12, 0x94643b84, | ||
113 | 0x0d6d6a3e, 0x7a6a5aa8, 0xe40ecf0b, 0x9309ff9d, 0x0a00ae27, 0x7d079eb1, | ||
114 | 0xf00f9344, 0x8708a3d2, 0x1e01f268, 0x6906c2fe, 0xf762575d, 0x806567cb, | ||
115 | 0x196c3671, 0x6e6b06e7, 0xfed41b76, 0x89d32be0, 0x10da7a5a, 0x67dd4acc, | ||
116 | 0xf9b9df6f, 0x8ebeeff9, 0x17b7be43, 0x60b08ed5, 0xd6d6a3e8, 0xa1d1937e, | ||
117 | 0x38d8c2c4, 0x4fdff252, 0xd1bb67f1, 0xa6bc5767, 0x3fb506dd, 0x48b2364b, | ||
118 | 0xd80d2bda, 0xaf0a1b4c, 0x36034af6, 0x41047a60, 0xdf60efc3, 0xa867df55, | ||
119 | 0x316e8eef, 0x4669be79, 0xcb61b38c, 0xbc66831a, 0x256fd2a0, 0x5268e236, | ||
120 | 0xcc0c7795, 0xbb0b4703, 0x220216b9, 0x5505262f, 0xc5ba3bbe, 0xb2bd0b28, | ||
121 | 0x2bb45a92, 0x5cb36a04, 0xc2d7ffa7, 0xb5d0cf31, 0x2cd99e8b, 0x5bdeae1d, | ||
122 | 0x9b64c2b0, 0xec63f226, 0x756aa39c, 0x026d930a, 0x9c0906a9, 0xeb0e363f, | ||
123 | 0x72076785, 0x05005713, 0x95bf4a82, 0xe2b87a14, 0x7bb12bae, 0x0cb61b38, | ||
124 | 0x92d28e9b, 0xe5d5be0d, 0x7cdcefb7, 0x0bdbdf21, 0x86d3d2d4, 0xf1d4e242, | ||
125 | 0x68ddb3f8, 0x1fda836e, 0x81be16cd, 0xf6b9265b, 0x6fb077e1, 0x18b74777, | ||
126 | 0x88085ae6, 0xff0f6a70, 0x66063bca, 0x11010b5c, 0x8f659eff, 0xf862ae69, | ||
127 | 0x616bffd3, 0x166ccf45, 0xa00ae278, 0xd70dd2ee, 0x4e048354, 0x3903b3c2, | ||
128 | 0xa7672661, 0xd06016f7, 0x4969474d, 0x3e6e77db, 0xaed16a4a, 0xd9d65adc, | ||
129 | 0x40df0b66, 0x37d83bf0, 0xa9bcae53, 0xdebb9ec5, 0x47b2cf7f, 0x30b5ffe9, | ||
130 | 0xbdbdf21c, 0xcabac28a, 0x53b39330, 0x24b4a3a6, 0xbad03605, 0xcdd70693, | ||
131 | 0x54de5729, 0x23d967bf, 0xb3667a2e, 0xc4614ab8, 0x5d681b02, 0x2a6f2b94, | ||
132 | 0xb40bbe37, 0xc30c8ea1, 0x5a05df1b, 0x2d02ef8d | ||
133 | }; | ||
134 | |||
135 | |||
136 | ///---------------------------------------------------------------------------- | ||
137 | /// Class llcrc | ||
138 | ///---------------------------------------------------------------------------- | ||
139 | |||
140 | // Default constructor | ||
141 | LLCRC::LLCRC() : mCurrent(0xffffffff) | ||
142 | { | ||
143 | } | ||
144 | |||
145 | |||
146 | U32 LLCRC::getCRC() const | ||
147 | { | ||
148 | return ~mCurrent; | ||
149 | } | ||
150 | |||
151 | void LLCRC::update(U8 next_byte) | ||
152 | { | ||
153 | mCurrent = UPDC32(next_byte, mCurrent); | ||
154 | } | ||
155 | |||
156 | void LLCRC::update(const U8* buffer, U32 buffer_size) | ||
157 | { | ||
158 | for ( ; buffer_size; --buffer_size, ++buffer) | ||
159 | { | ||
160 | mCurrent = UPDC32(*buffer, mCurrent); | ||
161 | } | ||
162 | } | ||
163 | |||
164 | void LLCRC::update(const char *filename) | ||
165 | { | ||
166 | FILE *fp = LLFile::fopen(filename, "rb"); | ||
167 | |||
168 | if (fp) | ||
169 | { | ||
170 | fseek(fp, 0, SEEK_END); | ||
171 | U32 size = ftell(fp); | ||
172 | |||
173 | fseek(fp, 0, SEEK_SET); | ||
174 | |||
175 | U8 *data = new U8[size]; | ||
176 | fread(data, size, 1, fp); | ||
177 | fclose(fp); | ||
178 | |||
179 | update(data, size); | ||
180 | delete[] data; | ||
181 | } | ||
182 | } | ||
183 | |||
184 | |||
185 | #ifdef _DEBUG | ||
186 | BOOL LLCRC::testHarness() | ||
187 | { | ||
188 | const S32 TEST_BUFFER_SIZE = 16; | ||
189 | const char TEST_BUFFER[TEST_BUFFER_SIZE] = "hello &#$)$&Nd0"; | ||
190 | LLCRC c1, c2; | ||
191 | c1.update((U8*)TEST_BUFFER, TEST_BUFFER_SIZE - 1); | ||
192 | char* rh = (char*)TEST_BUFFER; | ||
193 | while(*rh != '\0') | ||
194 | { | ||
195 | c2.update(*rh); | ||
196 | ++rh; | ||
197 | } | ||
198 | return(c1.getCRC() == c2.getCRC()); | ||
199 | } | ||
200 | #endif | ||
201 | |||
202 | |||
203 | |||
204 | ///---------------------------------------------------------------------------- | ||
205 | /// Local function definitions | ||
206 | ///---------------------------------------------------------------------------- | ||