wsutil/crc16.h

   1 /* crc16.h
   2  * Declaration of CRC-16 routines and table
   3  *
   4  * 2004 Richard van der Hoff <richardv@mxtelecom.com>
   5  *
   6  * $Id$
   7  *
   8  * Wireshark - Network traffic analyzer
   9  * By Gerald Combs <gerald@wireshark.org>
  10  * Copyright 1998 Gerald Combs
  11  *
  12  * This program is free software; you can redistribute it and/or
  13  * modify it under the terms of the GNU General Public License
  14  * as published by the Free Software Foundation; either version 2
  15  * of the License, or (at your option) any later version.
  16  *
  17  * This program is distributed in the hope that it will be useful,
  18  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  19  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  20  * GNU General Public License for more details.
  21  *
  22  * You should have received a copy of the GNU General Public License
  23  * along with this program; if not, write to the Free Software
  24  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  25 */
  26
  27 #ifndef __CRC16_H__
  28 #define __CRC16_H__
  29
  30 #include "ws_symbol_export.h"
  31
  32 #ifdef __cplusplus
  33 extern "C" {
  34 #endif /* __cplusplus */
  35
  36 /* Calculate the CCITT/ITU/CRC-16 16-bit CRC
  37
  38    (parameters for this CRC are:
  39        Polynomial: x^16 + x^12 + x^5 + 1  (0x1021);
  40        Start value 0xFFFF;
  41        XOR result with 0xFFFF;
  42        First bit is LSB)
  43 */
  44
  45 /** Compute CRC16 CCITT checksum of a buffer of data.
  46  @param buf The buffer containing the data.
  47  @param len The number of bytes to include in the computation.
  48  @return The CRC16 CCITT checksum. */
  49 WS_DLL_PUBLIC guint16 crc16_ccitt(const guint8 *buf, guint len);
  50
  51 /** Compute CRC16 X.25 CCITT checksum of a buffer of data.
  52  @param buf The buffer containing the data.
  53  @param len The number of bytes to include in the computation.
  54  @return The CRC16 X.25 CCITT checksum. */
  55 WS_DLL_PUBLIC guint16 crc16_x25_ccitt(const guint8 *buf, guint len);
  56
  57 /** Compute CRC16 CCITT checksum of a buffer of data.  If computing the
  58  *  checksum over multiple buffers and you want to feed the partial CRC16
  59  *  back in, remember to take the 1's complement of the partial CRC16 first.
  60  @param buf The buffer containing the data.
  61  @param len The number of bytes to include in the computation.
  62  @param seed The seed to use.
  63  @return The CRC16 CCITT checksum (using the given seed). */
  64 WS_DLL_PUBLIC guint16 crc16_ccitt_seed(const guint8 *buf, guint len, guint16 seed);
  65
  66 /** Calculates a CRC16 checksum for the given buffer with the polynom
  67  *  0x5935 using a precompiled CRC table
  68  * @param buf a pointer to a buffer of the given length
  69  * @param len the length of the given buffer
  70  * @param seed The seed to use.
  71  * @return the CRC16 checksum for the buffer
  72  */
  73 WS_DLL_PUBLIC guint16 crc16_0x5935(const guint8 *buf, guint32 len, guint16 seed);
  74
  75 /** Calculates a CRC16 checksum for the given buffer with the polynom
  76  *  0x755B using a precompiled CRC table
  77  * @param buf a pointer to a buffer of the given length
  78  * @param len the length of the given buffer
  79  * @param seed The seed to use.
  80  * @return the CRC16 checksum for the buffer
  81  */
  82 WS_DLL_PUBLIC guint16 crc16_0x755B(const guint8 *buf, guint32 len, guint16 seed);
  83
  84 /** Computes CRC16 checksum for the given data with the polynom 0x9949 using
  85  *  precompiled CRC table
  86  * @param buf a pointer to a buffer of the given length
  87  * @param len the length of the given buffer
  88  * @param seed The seed to use.
  89  * @return the CRC16 checksum for the buffer
  90  */
  91 WS_DLL_PUBLIC guint16 crc16_0x9949_seed(const guint8 *buf, guint len, guint16 seed);
  92
  93 #ifdef __cplusplus
  94 }
  95 #endif /* __cplusplus */
  96
  97 #endif /* crc16.h */