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5191 | serge | 1 | /* crc32.c |
2 | Copyright (C) 2009, 2011 Free Software Foundation, Inc. |
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3 | |||
4 | This file is part of the libiberty library. |
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5 | |||
6 | This file is free software; you can redistribute it and/or modify |
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7 | it under the terms of the GNU General Public License as published by |
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8 | the Free Software Foundation; either version 2 of the License, or |
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9 | (at your option) any later version. |
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10 | |||
11 | In addition to the permissions in the GNU General Public License, the |
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12 | Free Software Foundation gives you unlimited permission to link the |
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13 | compiled version of this file into combinations with other programs, |
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14 | and to distribute those combinations without any restriction coming |
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15 | from the use of this file. (The General Public License restrictions |
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16 | do apply in other respects; for example, they cover modification of |
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17 | the file, and distribution when not linked into a combined |
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18 | executable.) |
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19 | |||
20 | This program is distributed in the hope that it will be useful, |
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21 | but WITHOUT ANY WARRANTY; without even the implied warranty of |
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22 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
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23 | GNU General Public License for more details. |
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24 | |||
25 | You should have received a copy of the GNU General Public License |
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26 | along with this program; if not, write to the Free Software |
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27 | Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston, MA 02110-1301, USA. |
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28 | */ |
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29 | |||
30 | #ifdef HAVE_CONFIG_H |
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31 | #include "config.h" |
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32 | #endif |
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33 | |||
34 | #include "libiberty.h" |
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35 | |||
36 | /* This table was generated by the following program. This matches |
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37 | what gdb does. |
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38 | |||
39 | #include |
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40 | |||
41 | int |
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42 | main () |
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43 | { |
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44 | int i, j; |
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45 | unsigned int c; |
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46 | int table[256]; |
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47 | |||
48 | for (i = 0; i < 256; i++) |
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49 | { |
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50 | for (c = i << 24, j = 8; j > 0; --j) |
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51 | c = c & 0x80000000 ? (c << 1) ^ 0x04c11db7 : (c << 1); |
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52 | table[i] = c; |
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53 | } |
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54 | |||
55 | printf ("static const unsigned int crc32_table[] =\n{\n"); |
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56 | for (i = 0; i < 256; i += 4) |
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57 | { |
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58 | printf (" 0x%08x, 0x%08x, 0x%08x, 0x%08x", |
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59 | table[i + 0], table[i + 1], table[i + 2], table[i + 3]); |
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60 | if (i + 4 < 256) |
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61 | putchar (','); |
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62 | putchar ('\n'); |
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63 | } |
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64 | printf ("};\n"); |
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65 | return 0; |
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66 | } |
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67 | |||
68 | For more information on CRC, see, e.g., |
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69 | http://www.ross.net/crc/download/crc_v3.txt. */ |
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70 | |||
71 | static const unsigned int crc32_table[] = |
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72 | { |
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73 | 0x00000000, 0x04c11db7, 0x09823b6e, 0x0d4326d9, |
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74 | 0x130476dc, 0x17c56b6b, 0x1a864db2, 0x1e475005, |
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75 | 0x2608edb8, 0x22c9f00f, 0x2f8ad6d6, 0x2b4bcb61, |
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76 | 0x350c9b64, 0x31cd86d3, 0x3c8ea00a, 0x384fbdbd, |
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77 | 0x4c11db70, 0x48d0c6c7, 0x4593e01e, 0x4152fda9, |
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78 | 0x5f15adac, 0x5bd4b01b, 0x569796c2, 0x52568b75, |
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79 | 0x6a1936c8, 0x6ed82b7f, 0x639b0da6, 0x675a1011, |
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80 | 0x791d4014, 0x7ddc5da3, 0x709f7b7a, 0x745e66cd, |
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81 | 0x9823b6e0, 0x9ce2ab57, 0x91a18d8e, 0x95609039, |
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82 | 0x8b27c03c, 0x8fe6dd8b, 0x82a5fb52, 0x8664e6e5, |
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83 | 0xbe2b5b58, 0xbaea46ef, 0xb7a96036, 0xb3687d81, |
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84 | 0xad2f2d84, 0xa9ee3033, 0xa4ad16ea, 0xa06c0b5d, |
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85 | 0xd4326d90, 0xd0f37027, 0xddb056fe, 0xd9714b49, |
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86 | 0xc7361b4c, 0xc3f706fb, 0xceb42022, 0xca753d95, |
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87 | 0xf23a8028, 0xf6fb9d9f, 0xfbb8bb46, 0xff79a6f1, |
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88 | 0xe13ef6f4, 0xe5ffeb43, 0xe8bccd9a, 0xec7dd02d, |
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89 | 0x34867077, 0x30476dc0, 0x3d044b19, 0x39c556ae, |
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90 | 0x278206ab, 0x23431b1c, 0x2e003dc5, 0x2ac12072, |
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91 | 0x128e9dcf, 0x164f8078, 0x1b0ca6a1, 0x1fcdbb16, |
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92 | 0x018aeb13, 0x054bf6a4, 0x0808d07d, 0x0cc9cdca, |
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93 | 0x7897ab07, 0x7c56b6b0, 0x71159069, 0x75d48dde, |
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94 | 0x6b93dddb, 0x6f52c06c, 0x6211e6b5, 0x66d0fb02, |
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95 | 0x5e9f46bf, 0x5a5e5b08, 0x571d7dd1, 0x53dc6066, |
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96 | 0x4d9b3063, 0x495a2dd4, 0x44190b0d, 0x40d816ba, |
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97 | 0xaca5c697, 0xa864db20, 0xa527fdf9, 0xa1e6e04e, |
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98 | 0xbfa1b04b, 0xbb60adfc, 0xb6238b25, 0xb2e29692, |
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99 | 0x8aad2b2f, 0x8e6c3698, 0x832f1041, 0x87ee0df6, |
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100 | 0x99a95df3, 0x9d684044, 0x902b669d, 0x94ea7b2a, |
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101 | 0xe0b41de7, 0xe4750050, 0xe9362689, 0xedf73b3e, |
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102 | 0xf3b06b3b, 0xf771768c, 0xfa325055, 0xfef34de2, |
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103 | 0xc6bcf05f, 0xc27dede8, 0xcf3ecb31, 0xcbffd686, |
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104 | 0xd5b88683, 0xd1799b34, 0xdc3abded, 0xd8fba05a, |
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105 | 0x690ce0ee, 0x6dcdfd59, 0x608edb80, 0x644fc637, |
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106 | 0x7a089632, 0x7ec98b85, 0x738aad5c, 0x774bb0eb, |
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107 | 0x4f040d56, 0x4bc510e1, 0x46863638, 0x42472b8f, |
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108 | 0x5c007b8a, 0x58c1663d, 0x558240e4, 0x51435d53, |
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109 | 0x251d3b9e, 0x21dc2629, 0x2c9f00f0, 0x285e1d47, |
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110 | 0x36194d42, 0x32d850f5, 0x3f9b762c, 0x3b5a6b9b, |
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111 | 0x0315d626, 0x07d4cb91, 0x0a97ed48, 0x0e56f0ff, |
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112 | 0x1011a0fa, 0x14d0bd4d, 0x19939b94, 0x1d528623, |
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113 | 0xf12f560e, 0xf5ee4bb9, 0xf8ad6d60, 0xfc6c70d7, |
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114 | 0xe22b20d2, 0xe6ea3d65, 0xeba91bbc, 0xef68060b, |
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115 | 0xd727bbb6, 0xd3e6a601, 0xdea580d8, 0xda649d6f, |
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116 | 0xc423cd6a, 0xc0e2d0dd, 0xcda1f604, 0xc960ebb3, |
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117 | 0xbd3e8d7e, 0xb9ff90c9, 0xb4bcb610, 0xb07daba7, |
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118 | 0xae3afba2, 0xaafbe615, 0xa7b8c0cc, 0xa379dd7b, |
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119 | 0x9b3660c6, 0x9ff77d71, 0x92b45ba8, 0x9675461f, |
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120 | 0x8832161a, 0x8cf30bad, 0x81b02d74, 0x857130c3, |
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121 | 0x5d8a9099, 0x594b8d2e, 0x5408abf7, 0x50c9b640, |
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122 | 0x4e8ee645, 0x4a4ffbf2, 0x470cdd2b, 0x43cdc09c, |
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123 | 0x7b827d21, 0x7f436096, 0x7200464f, 0x76c15bf8, |
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124 | 0x68860bfd, 0x6c47164a, 0x61043093, 0x65c52d24, |
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125 | 0x119b4be9, 0x155a565e, 0x18197087, 0x1cd86d30, |
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126 | 0x029f3d35, 0x065e2082, 0x0b1d065b, 0x0fdc1bec, |
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127 | 0x3793a651, 0x3352bbe6, 0x3e119d3f, 0x3ad08088, |
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128 | 0x2497d08d, 0x2056cd3a, 0x2d15ebe3, 0x29d4f654, |
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129 | 0xc5a92679, 0xc1683bce, 0xcc2b1d17, 0xc8ea00a0, |
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130 | 0xd6ad50a5, 0xd26c4d12, 0xdf2f6bcb, 0xdbee767c, |
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131 | 0xe3a1cbc1, 0xe760d676, 0xea23f0af, 0xeee2ed18, |
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132 | 0xf0a5bd1d, 0xf464a0aa, 0xf9278673, 0xfde69bc4, |
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133 | 0x89b8fd09, 0x8d79e0be, 0x803ac667, 0x84fbdbd0, |
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134 | 0x9abc8bd5, 0x9e7d9662, 0x933eb0bb, 0x97ffad0c, |
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135 | 0xafb010b1, 0xab710d06, 0xa6322bdf, 0xa2f33668, |
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136 | 0xbcb4666d, 0xb8757bda, 0xb5365d03, 0xb1f740b4 |
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137 | }; |
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138 | |||
139 | /* |
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140 | |||
141 | @deftypefn Extension {unsigned int} crc32 (const unsigned char *@var{buf}, @ |
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142 | int @var{len}, unsigned int @var{init}) |
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143 | |||
144 | Compute the 32-bit CRC of @var{buf} which has length @var{len}. The |
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145 | starting value is @var{init}; this may be used to compute the CRC of |
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146 | data split across multiple buffers by passing the return value of each |
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147 | call as the @var{init} parameter of the next. |
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148 | |||
149 | This is intended to match the CRC used by the @command{gdb} remote |
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150 | protocol for the @samp{qCRC} command. In order to get the same |
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151 | results as gdb for a block of data, you must pass the first CRC |
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152 | parameter as @code{0xffffffff}. |
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153 | |||
154 | This CRC can be specified as: |
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155 | |||
156 | Width : 32 |
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157 | Poly : 0x04c11db7 |
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158 | Init : parameter, typically 0xffffffff |
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159 | RefIn : false |
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160 | RefOut : false |
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161 | XorOut : 0 |
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162 | |||
163 | This differs from the "standard" CRC-32 algorithm in that the values |
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164 | are not reflected, and there is no final XOR value. These differences |
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165 | make it easy to compose the values of multiple blocks. |
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166 | |||
167 | @end deftypefn |
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168 | |||
169 | */ |
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170 | |||
171 | unsigned int |
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172 | xcrc32 (const unsigned char *buf, int len, unsigned int init) |
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173 | { |
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174 | unsigned int crc = init; |
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175 | while (len--) |
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176 | { |
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177 | crc = (crc << 8) ^ crc32_table[((crc >> 24) ^ *buf) & 255]; |
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178 | buf++; |
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179 | } |
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180 | return crc; |
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181 | }><>>>><>><>><>> |