1 #include "stdio.h"
2 #define sss "CREATED"
3 //#define sss "created"
4 #define ssslen 7
5
6 #define UINT16 unsigned short
7
8 /*
9 * Update the CRC16 for a single byte
10 * Init value of crc should be zero (at first call for string)
11 */
byteCRC16(int value,int init)12 int byteCRC16(int value, int init)
13 {
14 int k = (((init >> 8) ^ value) & 0xff) << 8;
15 int crc = 0;
16 int bits = 8;
17 do{
18 if (( crc ^ k ) & 0x8000)
19 crc = (crc << 1) ^ 0x1021;
20 else
21 crc <<= 1;
22 k <<= 1;
23 }
24 while (--bits);
25 return ((init << 8) ^ crc);
26 }
27
28 #define _byteCRC16_(b, crc) (UINT16)((crc << 8) ^ crc16tab[((crc >> 8) ^ (b)) & 0xff])
29
30 const UINT16 crc16tab[] =
31 {
32 0x0000, 0x1021, 0x2042, 0x3063, 0x4084, 0x50A5, 0x60C6, 0x70E7,
33 0x8108, 0x9129, 0xA14A, 0xB16B, 0xC18C, 0xD1AD, 0xE1CE, 0xF1EF,
34 0x1231, 0x0210, 0x3273, 0x2252, 0x52B5, 0x4294, 0x72F7, 0x62D6,
35 0x9339, 0x8318, 0xB37B, 0xA35A, 0xD3BD, 0xC39C, 0xF3FF, 0xE3DE,
36 0x2462, 0x3443, 0x0420, 0x1401, 0x64E6, 0x74C7, 0x44A4, 0x5485,
37 0xA56A, 0xB54B, 0x8528, 0x9509, 0xE5EE, 0xF5CF, 0xC5AC, 0xD58D,
38 0x3653, 0x2672, 0x1611, 0x0630, 0x76D7, 0x66F6, 0x5695, 0x46B4,
39 0xB75B, 0xA77A, 0x9719, 0x8738, 0xF7DF, 0xE7FE, 0xD79D, 0xC7BC,
40 0x48C4, 0x58E5, 0x6886, 0x78A7, 0x0840, 0x1861, 0x2802, 0x3823,
41 0xC9CC, 0xD9ED, 0xE98E, 0xF9AF, 0x8948, 0x9969, 0xA90A, 0xB92B,
42 0x5AF5, 0x4AD4, 0x7AB7, 0x6A96, 0x1A71, 0x0A50, 0x3A33, 0x2A12,
43 0xDBFD, 0xCBDC, 0xFBBF, 0xEB9E, 0x9B79, 0x8B58, 0xBB3B, 0xAB1A,
44 0x6CA6, 0x7C87, 0x4CE4, 0x5CC5, 0x2C22, 0x3C03, 0x0C60, 0x1C41,
45 0xEDAE, 0xFD8F, 0xCDEC, 0xDDCD, 0xAD2A, 0xBD0B, 0x8D68, 0x9D49,
46 0x7E97, 0x6EB6, 0x5ED5, 0x4EF4, 0x3E13, 0x2E32, 0x1E51, 0x0E70,
47 0xFF9F, 0xEFBE, 0xDFDD, 0xCFFC, 0xBF1B, 0xAF3A, 0x9F59, 0x8F78,
48 0x9188, 0x81A9, 0xB1CA, 0xA1EB, 0xD10C, 0xC12D, 0xF14E, 0xE16F,
49 0x1080, 0x00A1, 0x30C2, 0x20E3, 0x5004, 0x4025, 0x7046, 0x6067,
50 0x83B9, 0x9398, 0xA3FB, 0xB3DA, 0xC33D, 0xD31C, 0xE37F, 0xF35E,
51 0x02B1, 0x1290, 0x22F3, 0x32D2, 0x4235, 0x5214, 0x6277, 0x7256,
52 0xB5EA, 0xA5CB, 0x95A8, 0x8589, 0xF56E, 0xE54F, 0xD52C, 0xC50D,
53 0x34E2, 0x24C3, 0x14A0, 0x0481, 0x7466, 0x6447, 0x5424, 0x4405,
54 0xA7DB, 0xB7FA, 0x8799, 0x97B8, 0xE75F, 0xF77E, 0xC71D, 0xD73C,
55 0x26D3, 0x36F2, 0x0691, 0x16B0, 0x6657, 0x7676, 0x4615, 0x5634,
56 0xD94C, 0xC96D, 0xF90E, 0xE92F, 0x99C8, 0x89E9, 0xB98A, 0xA9AB,
57 0x5844, 0x4865, 0x7806, 0x6827, 0x18C0, 0x08E1, 0x3882, 0x28A3,
58 0xCB7D, 0xDB5C, 0xEB3F, 0xFB1E, 0x8BF9, 0x9BD8, 0xABBB, 0xBB9A,
59 0x4A75, 0x5A54, 0x6A37, 0x7A16, 0x0AF1, 0x1AD0, 0x2AB3, 0x3A92,
60 0xFD2E, 0xED0F, 0xDD6C, 0xCD4D, 0xBDAA, 0xAD8B, 0x9DE8, 0x8DC9,
61 0x7C26, 0x6C07, 0x5C64, 0x4C45, 0x3CA2, 0x2C83, 0x1CE0, 0x0CC1,
62 0xEF1F, 0xFF3E, 0xCF5D, 0xDF7C, 0xAF9B, 0xBFBA, 0x8FD9, 0x9FF8,
63 0x6E17, 0x7E36, 0x4E55, 0x5E74, 0x2E93, 0x3EB2, 0x0ED1, 0x1EF0
64 };
65
66
67 /*
68 * Calculate the CRC16 for a array of bytes (fast method).
69 */
memCRC16(unsigned int len,char * buffer)70 UINT16 memCRC16(unsigned int len, char *buffer) {
71
72 int crc = 0;
73
74 if(!len) return 0;
75
76 do {
77 unsigned int value = *buffer++;
78 crc = byteCRC16(value, crc);
79 }
80 while (--len);
81 return crc;
82 }
83
84 /*
85 * Calculate the CRC16 for a array of bytes (slow method).
86 */
_memCRC16_(unsigned int len,char * buffer)87 UINT16 _memCRC16_(unsigned int len, char *buffer) {
88
89 int crc = 0;
90
91 if(!len) return 0;
92
93 do {
94 unsigned int value = *buffer++;
95 crc = _byteCRC16_(value, crc);
96 }
97 while (--len);
98 return crc;
99 }
100
101
102
main(int argc,char ** argv)103 main(int argc, char **argv){
104
105 unsigned crc=0;
106
107 crc=_memCRC16_(ssslen,sss);
108 printf("Slow CRC16 %s 0x%0X\n", sss, crc);
109
110 crc=memCRC16(ssslen,sss);
111 printf("Fast CRC16 %s 0x%0X\n", sss, crc);
112
113 if(argc>1){
114 unsigned cc, crcfast=0, crcslow=0;
115 FILE *fd;
116
117 fd = fopen(argv[1],"r");
118 if(fd){
119 while((cc = getc(fd))!=EOF){
120 crcslow=_byteCRC16_((unsigned char)cc,crcslow);
121 crcfast=_byteCRC16_((unsigned char)cc,crcfast);
122 }
123 fclose(fd);
124 }
125 printf("Slow CRC16 file '%s' 0x%0X\n", argv[1], crcslow);
126 printf("Fast CRC16 file '%s' 0x%0X\n", argv[1], crcfast);
127
128 }
129 }
130