1 /*****************************************************************************
2 * Copyright ©2017-2019 Gemalto – a Thales Company. All rights Reserved.
3 *
4 * This copy is licensed under the Apache License, Version 2.0 (the "License");
5 * You may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at:
7 * http://www.apache.org/licenses/LICENSE-2.0 or https://www.apache.org/licenses/LICENSE-2.0.html
8 *
9 * Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
10 * See the License for the specific language governing permissions and limitations under the License.
11
12 ****************************************************************************/
13
14 /**
15 * @file
16 * $Author$
17 * $Revision$
18 * $Date$
19 *
20 * Implementation for both checksum alogrihtms used by T=1 transport.
21 *
22 */
23
24 #include <stddef.h>
25 #include <stdint.h>
26
27 #include "checksum.h"
28
29 unsigned
lrc8(const void * s,size_t n)30 lrc8(const void *s, size_t n)
31 {
32 const uint8_t *p = s;
33 uint8_t c = 0;
34
35 if (p)
36 while (n--)
37 c ^= *p++;
38 return c;
39 }
40
41 unsigned
crc_ccitt(uint16_t crc,const void * s,size_t n)42 crc_ccitt(uint16_t crc, const void *s, size_t n)
43 {
44 /* CRC16 reference implementation can also be found in RFC 1662.
45 * But this is the CRC16/MCRF4XX variant used in T=1.
46 * http://reveng.sourceforge.net/crc-catalogue/all.htm#crc.cat.crc-16-mcrf4xx
47 *
48 * More information here:
49 * http://reveng.sourceforge.net/crc-catalogue/all.htm#appendix
50 */
51
52 static const uint16_t fast[256] = {
53 0x0000, 0x1189, 0x2312, 0x329B, 0x4624, 0x57AD, 0x6536, 0x74BF,
54 0x8C48, 0x9DC1, 0xAF5A, 0xBED3, 0xCA6C, 0xDBE5, 0xE97E, 0xF8F7,
55 0x1081, 0x0108, 0x3393, 0x221A, 0x56A5, 0x472C, 0x75B7, 0x643E,
56 0x9CC9, 0x8D40, 0xBFDB, 0xAE52, 0xDAED, 0xCB64, 0xF9FF, 0xE876,
57 0x2102, 0x308B, 0x0210, 0x1399, 0x6726, 0x76AF, 0x4434, 0x55BD,
58 0xAD4A, 0xBCC3, 0x8E58, 0x9FD1, 0xEB6E, 0xFAE7, 0xC87C, 0xD9F5,
59 0x3183, 0x200A, 0x1291, 0x0318, 0x77A7, 0x662E, 0x54B5, 0x453C,
60 0xBDCB, 0xAC42, 0x9ED9, 0x8F50, 0xFBEF, 0xEA66, 0xD8FD, 0xC974,
61 0x4204, 0x538D, 0x6116, 0x709F, 0x0420, 0x15A9, 0x2732, 0x36BB,
62 0xCE4C, 0xDFC5, 0xED5E, 0xFCD7, 0x8868, 0x99E1, 0xAB7A, 0xBAF3,
63 0x5285, 0x430C, 0x7197, 0x601E, 0x14A1, 0x0528, 0x37B3, 0x263A,
64 0xDECD, 0xCF44, 0xFDDF, 0xEC56, 0x98E9, 0x8960, 0xBBFB, 0xAA72,
65 0x6306, 0x728F, 0x4014, 0x519D, 0x2522, 0x34AB, 0x0630, 0x17B9,
66 0xEF4E, 0xFEC7, 0xCC5C, 0xDDD5, 0xA96A, 0xB8E3, 0x8A78, 0x9BF1,
67 0x7387, 0x620E, 0x5095, 0x411C, 0x35A3, 0x242A, 0x16B1, 0x0738,
68 0xFFCF, 0xEE46, 0xDCDD, 0xCD54, 0xB9EB, 0xA862, 0x9AF9, 0x8B70,
69 0x8408, 0x9581, 0xA71A, 0xB693, 0xC22C, 0xD3A5, 0xE13E, 0xF0B7,
70 0x0840, 0x19C9, 0x2B52, 0x3ADB, 0x4E64, 0x5FED, 0x6D76, 0x7CFF,
71 0x9489, 0x8500, 0xB79B, 0xA612, 0xD2AD, 0xC324, 0xF1BF, 0xE036,
72 0x18C1, 0x0948, 0x3BD3, 0x2A5A, 0x5EE5, 0x4F6C, 0x7DF7, 0x6C7E,
73 0xA50A, 0xB483, 0x8618, 0x9791, 0xE32E, 0xF2A7, 0xC03C, 0xD1B5,
74 0x2942, 0x38CB, 0x0A50, 0x1BD9, 0x6F66, 0x7EEF, 0x4C74, 0x5DFD,
75 0xB58B, 0xA402, 0x9699, 0x8710, 0xF3AF, 0xE226, 0xD0BD, 0xC134,
76 0x39C3, 0x284A, 0x1AD1, 0x0B58, 0x7FE7, 0x6E6E, 0x5CF5, 0x4D7C,
77 0xC60C, 0xD785, 0xE51E, 0xF497, 0x8028, 0x91A1, 0xA33A, 0xB2B3,
78 0x4A44, 0x5BCD, 0x6956, 0x78DF, 0x0C60, 0x1DE9, 0x2F72, 0x3EFB,
79 0xD68D, 0xC704, 0xF59F, 0xE416, 0x90A9, 0x8120, 0xB3BB, 0xA232,
80 0x5AC5, 0x4B4C, 0x79D7, 0x685E, 0x1CE1, 0x0D68, 0x3FF3, 0x2E7A,
81 0xE70E, 0xF687, 0xC41C, 0xD595, 0xA12A, 0xB0A3, 0x8238, 0x93B1,
82 0x6B46, 0x7ACF, 0x4854, 0x59DD, 0x2D62, 0x3CEB, 0x0E70, 0x1FF9,
83 0xF78F, 0xE606, 0xD49D, 0xC514, 0xB1AB, 0xA022, 0x92B9, 0x8330,
84 0x7BC7, 0x6A4E, 0x58D5, 0x495C, 0x3DE3, 0x2C6A, 0x1EF1, 0x0F78
85 };
86
87 const uint8_t *p = s;
88
89 if (s)
90 while(n--)
91 crc = (uint8_t)(crc >> 8) ^ fast[(uint8_t)(crc ^ *p++)];
92 return crc;
93 }
94