source: SVN/cambria/redboot/packages/services/crc/current/src/crc16.c @ 1

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1//==========================================================================
2//
3//      crc16.c
4//
5//      16 bit CRC with polynomial x^16+x^12+x^5+1
6//
7//==========================================================================
8//####ECOSGPLCOPYRIGHTBEGIN####
9// -------------------------------------------
10// This file is part of eCos, the Embedded Configurable Operating System.
11// Copyright (C) 1998, 1999, 2000, 2001, 2002 Red Hat, Inc.
12// Copyright (C) 2002 Gary Thomas
13//
14// eCos is free software; you can redistribute it and/or modify it under
15// the terms of the GNU General Public License as published by the Free
16// Software Foundation; either version 2 or (at your option) any later version.
17//
18// eCos is distributed in the hope that it will be useful, but WITHOUT ANY
19// WARRANTY; without even the implied warranty of MERCHANTABILITY or
20// FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
21// for more details.
22//
23// You should have received a copy of the GNU General Public License along
24// with eCos; if not, write to the Free Software Foundation, Inc.,
25// 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA.
26//
27// As a special exception, if other files instantiate templates or use macros
28// or inline functions from this file, or you compile this file and link it
29// with other works to produce a work based on this file, this file does not
30// by itself cause the resulting work to be covered by the GNU General Public
31// License. However the source code for this file must still be made available
32// in accordance with section (3) of the GNU General Public License.
33//
34// This exception does not invalidate any other reasons why a work based on
35// this file might be covered by the GNU General Public License.
36//
37// Alternative licenses for eCos may be arranged by contacting Red Hat, Inc.
38// at http://sources.redhat.com/ecos/ecos-license/
39// -------------------------------------------
40//####ECOSGPLCOPYRIGHTEND####
41//==========================================================================
42//#####DESCRIPTIONBEGIN####
43//
44// Author(s):    gthomas
45// Contributors: gthomas,asl
46// Date:         2001-01-31
47// Purpose:     
48// Description: 
49//             
50// This code is part of eCos (tm).
51//
52//####DESCRIPTIONEND####
53//
54//==========================================================================
55
56#include <cyg/crc/crc.h>
57
58// Table of CRC constants - implements x^16+x^12+x^5+1
59static const cyg_uint16 crc16_tab[] = {
60    0x0000, 0x1021, 0x2042, 0x3063, 0x4084, 0x50a5, 0x60c6, 0x70e7, 
61    0x8108, 0x9129, 0xa14a, 0xb16b, 0xc18c, 0xd1ad, 0xe1ce, 0xf1ef, 
62    0x1231, 0x0210, 0x3273, 0x2252, 0x52b5, 0x4294, 0x72f7, 0x62d6, 
63    0x9339, 0x8318, 0xb37b, 0xa35a, 0xd3bd, 0xc39c, 0xf3ff, 0xe3de, 
64    0x2462, 0x3443, 0x0420, 0x1401, 0x64e6, 0x74c7, 0x44a4, 0x5485, 
65    0xa56a, 0xb54b, 0x8528, 0x9509, 0xe5ee, 0xf5cf, 0xc5ac, 0xd58d, 
66    0x3653, 0x2672, 0x1611, 0x0630, 0x76d7, 0x66f6, 0x5695, 0x46b4, 
67    0xb75b, 0xa77a, 0x9719, 0x8738, 0xf7df, 0xe7fe, 0xd79d, 0xc7bc, 
68    0x48c4, 0x58e5, 0x6886, 0x78a7, 0x0840, 0x1861, 0x2802, 0x3823, 
69    0xc9cc, 0xd9ed, 0xe98e, 0xf9af, 0x8948, 0x9969, 0xa90a, 0xb92b, 
70    0x5af5, 0x4ad4, 0x7ab7, 0x6a96, 0x1a71, 0x0a50, 0x3a33, 0x2a12, 
71    0xdbfd, 0xcbdc, 0xfbbf, 0xeb9e, 0x9b79, 0x8b58, 0xbb3b, 0xab1a, 
72    0x6ca6, 0x7c87, 0x4ce4, 0x5cc5, 0x2c22, 0x3c03, 0x0c60, 0x1c41, 
73    0xedae, 0xfd8f, 0xcdec, 0xddcd, 0xad2a, 0xbd0b, 0x8d68, 0x9d49, 
74    0x7e97, 0x6eb6, 0x5ed5, 0x4ef4, 0x3e13, 0x2e32, 0x1e51, 0x0e70, 
75    0xff9f, 0xefbe, 0xdfdd, 0xcffc, 0xbf1b, 0xaf3a, 0x9f59, 0x8f78, 
76    0x9188, 0x81a9, 0xb1ca, 0xa1eb, 0xd10c, 0xc12d, 0xf14e, 0xe16f, 
77    0x1080, 0x00a1, 0x30c2, 0x20e3, 0x5004, 0x4025, 0x7046, 0x6067, 
78    0x83b9, 0x9398, 0xa3fb, 0xb3da, 0xc33d, 0xd31c, 0xe37f, 0xf35e, 
79    0x02b1, 0x1290, 0x22f3, 0x32d2, 0x4235, 0x5214, 0x6277, 0x7256, 
80    0xb5ea, 0xa5cb, 0x95a8, 0x8589, 0xf56e, 0xe54f, 0xd52c, 0xc50d, 
81    0x34e2, 0x24c3, 0x14a0, 0x0481, 0x7466, 0x6447, 0x5424, 0x4405, 
82    0xa7db, 0xb7fa, 0x8799, 0x97b8, 0xe75f, 0xf77e, 0xc71d, 0xd73c, 
83    0x26d3, 0x36f2, 0x0691, 0x16b0, 0x6657, 0x7676, 0x4615, 0x5634, 
84    0xd94c, 0xc96d, 0xf90e, 0xe92f, 0x99c8, 0x89e9, 0xb98a, 0xa9ab, 
85    0x5844, 0x4865, 0x7806, 0x6827, 0x18c0, 0x08e1, 0x3882, 0x28a3, 
86    0xcb7d, 0xdb5c, 0xeb3f, 0xfb1e, 0x8bf9, 0x9bd8, 0xabbb, 0xbb9a, 
87    0x4a75, 0x5a54, 0x6a37, 0x7a16, 0x0af1, 0x1ad0, 0x2ab3, 0x3a92, 
88    0xfd2e, 0xed0f, 0xdd6c, 0xcd4d, 0xbdaa, 0xad8b, 0x9de8, 0x8dc9, 
89    0x7c26, 0x6c07, 0x5c64, 0x4c45, 0x3ca2, 0x2c83, 0x1ce0, 0x0cc1, 
90    0xef1f, 0xff3e, 0xcf5d, 0xdf7c, 0xaf9b, 0xbfba, 0x8fd9, 0x9ff8, 
91    0x6e17, 0x7e36, 0x4e55, 0x5e74, 0x2e93, 0x3eb2, 0x0ed1, 0x1ef0, 
92};
93
94cyg_uint16
95cyg_crc16(unsigned char *buf, int len)
96{
97    int i;
98    cyg_uint16 cksum;
99
100    cksum = 0;
101    for (i = 0;  i < len;  i++) {
102        cksum = crc16_tab[((cksum>>8) ^ *buf++) & 0xFF] ^ (cksum << 8);
103    }
104    return cksum;
105}
106
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