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1 | /* -*-c-*- |
| 2 | * |
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3 | * $Id: crc32.h,v 1.3 1999/05/06 19:51:35 mdw Exp $ |
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4 | * |
| 5 | * Calculating cyclic redundancy values (non-cryptographic!) |
| 6 | * |
| 7 | * (c) 1998 Straylight/Edgeware |
| 8 | */ |
| 9 | |
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10 | /*----- Licensing notice --------------------------------------------------* |
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11 | * |
| 12 | * This file is part of the mLib utilities library. |
| 13 | * |
| 14 | * mLib is free software; you can redistribute it and/or modify |
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15 | * it under the terms of the GNU Library General Public License as |
| 16 | * published by the Free Software Foundation; either version 2 of the |
| 17 | * License, or (at your option) any later version. |
| 18 | * |
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19 | * mLib is distributed in the hope that it will be useful, |
| 20 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
| 21 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
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22 | * GNU Library General Public License for more details. |
| 23 | * |
| 24 | * You should have received a copy of the GNU Library General Public |
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25 | * License along with mLib; if not, write to the Free |
| 26 | * Software Foundation, Inc., 59 Temple Place - Suite 330, Boston, |
| 27 | * MA 02111-1307, USA. |
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28 | */ |
| 29 | |
| 30 | /*----- Revision history --------------------------------------------------* |
| 31 | * |
| 32 | * $Log: crc32.h,v $ |
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33 | * Revision 1.3 1999/05/06 19:51:35 mdw |
| 34 | * Reformatted the LGPL notice a little bit. |
| 35 | * |
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36 | * Revision 1.2 1999/05/05 18:50:31 mdw |
| 37 | * Change licensing conditions to LGPL. |
| 38 | * |
| 39 | * Revision 1.1.1.1 1998/06/17 23:44:42 mdw |
| 40 | * Initial version of mLib |
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41 | * |
| 42 | */ |
| 43 | |
| 44 | #ifndef CRC32_H |
| 45 | #define CRC32_h |
| 46 | |
| 47 | #ifdef __cplusplus |
| 48 | extern "C" { |
| 49 | #endif |
| 50 | |
| 51 | /*----- External values ---------------------------------------------------*/ |
| 52 | |
| 53 | extern unsigned long crc32_table[256]; |
| 54 | |
| 55 | /*----- Macros ------------------------------------------------------------*/ |
| 56 | |
| 57 | /* --- @CRC32@ --- * |
| 58 | * |
| 59 | * Arguments: @unsigned long result@ = where to put the result |
| 60 | * @unsigned long crc@ = carryover from previous call, or zero |
| 61 | * @void *buf@ = pointer to buffer to check |
| 62 | * @size_t sz@ = size of the buffer |
| 63 | * |
| 64 | * Use: A restartable CRC calculator wrapped up in a macro. |
| 65 | */ |
| 66 | |
| 67 | #define CRC32(result, crc, buf, sz) do { \ |
| 68 | const unsigned char *_p = (const unsigned char *)(buf); \ |
| 69 | const unsigned char *_l = _p + (sz); \ |
| 70 | unsigned long _crc = ~(crc) & 0xffffffffu; \ |
| 71 | \ |
| 72 | while (_p < _l) \ |
| 73 | _crc = (_crc >> 8) ^ crc32_table[(*_p++ ^ _crc) & 0xffu]; \ |
| 74 | (result) = ~_crc & 0xffffffffu; \ |
| 75 | } while (0) |
| 76 | |
| 77 | /*----- Functions provided ------------------------------------------------*/ |
| 78 | |
| 79 | /* --- @crc32@ --- * |
| 80 | * |
| 81 | * Arguments: @unsigned long crc@ = carryover from previous call, or zero |
| 82 | * @const void *buf@ = pointer to buffer to check |
| 83 | * @size_t sz@ = size of the buffer |
| 84 | * |
| 85 | * Returns: The CRC updated by the new buffer. |
| 86 | * |
| 87 | * Use: A restartable CRC calculator. This is just a function |
| 88 | * wrapper for the macro version. |
| 89 | */ |
| 90 | |
| 91 | extern unsigned long crc32(unsigned long /*crc*/, |
| 92 | const void */*buf*/, size_t /*sz*/); |
| 93 | |
| 94 | /*----- That's all, folks -------------------------------------------------*/ |
| 95 | |
| 96 | #ifdef __cplusplus |
| 97 | } |
| 98 | #endif |
| 99 | |
| 100 | #endif |
~mdw / mLib / blame