CDMS_CODE_samp_23SEP_DMA_flag
Dependencies: FreescaleIAP SimpleDMA mbed-rtos mbed
Fork of CDMS_CODE_samp_23SEP_DMA by
crc.h@145:fb800fecf128, 2016-04-02 (annotated)
- Committer:
- ee12b079
- Date:
- Sat Apr 02 11:54:50 2016 +0000
- Revision:
- 145:fb800fecf128
- Parent:
- 6:79d422d1ed42
worked for PL
Who changed what in which revision?
User | Revision | Line number | New contents of line |
---|---|---|---|
shreeshas95 | 0:f016e9e8d48b | 1 | //EDITS |
shreeshas95 | 0:f016e9e8d48b | 2 | //changed the initial remainder from 0x0000 to 0xffff according to the standards |
shreeshas95 | 0:f016e9e8d48b | 3 | //made two seperate functions crc16_gen and crc8_gen |
shreeshas95 | 0:f016e9e8d48b | 4 | |
shreeshas95 | 0:f016e9e8d48b | 5 | #define TOPBIT16 (1 << 15) |
shreeshas95 | 0:f016e9e8d48b | 6 | #define TOPBIT8 (1 << 7) |
shreeshas95 | 0:f016e9e8d48b | 7 | #define POLYNOMIAL16 0x1021 |
shreeshas95 | 6:79d422d1ed42 | 8 | #define POLYNOMIAL8 0x07 |
shreeshas95 | 0:f016e9e8d48b | 9 | |
shreeshas95 | 0:f016e9e8d48b | 10 | typedef uint16_t crctype16; |
shreeshas95 | 0:f016e9e8d48b | 11 | crctype16 crc16_gen(const unsigned char message[], unsigned int nBytes){ |
shreeshas95 | 0:f016e9e8d48b | 12 | crctype16 remainder = 0xffff; |
shreeshas95 | 0:f016e9e8d48b | 13 | int byte; |
shreeshas95 | 0:f016e9e8d48b | 14 | char bit; |
shreeshas95 | 0:f016e9e8d48b | 15 | |
shreeshas95 | 0:f016e9e8d48b | 16 | for( byte = 0 ; byte < nBytes ; byte++ ){ |
shreeshas95 | 0:f016e9e8d48b | 17 | /* |
shreeshas95 | 0:f016e9e8d48b | 18 | Bring the data byte by byte |
shreeshas95 | 0:f016e9e8d48b | 19 | each time only one byte is brought |
shreeshas95 | 0:f016e9e8d48b | 20 | 0 xor x = x |
shreeshas95 | 0:f016e9e8d48b | 21 | */ |
shreeshas95 | 0:f016e9e8d48b | 22 | remainder = remainder ^ ( message[byte] << 8 ); |
shreeshas95 | 0:f016e9e8d48b | 23 | |
shreeshas95 | 0:f016e9e8d48b | 24 | for( bit = 8 ; bit > 0 ; bit--){ |
shreeshas95 | 0:f016e9e8d48b | 25 | /* |
shreeshas95 | 0:f016e9e8d48b | 26 | for each bit, xor the remainder with polynomial |
shreeshas95 | 0:f016e9e8d48b | 27 | if the MSB is 1 |
shreeshas95 | 0:f016e9e8d48b | 28 | */ |
shreeshas95 | 0:f016e9e8d48b | 29 | if(remainder & TOPBIT16){ |
shreeshas95 | 0:f016e9e8d48b | 30 | remainder = (remainder << 1) ^ POLYNOMIAL16; |
shreeshas95 | 0:f016e9e8d48b | 31 | /* |
shreeshas95 | 0:f016e9e8d48b | 32 | each time the remainder is xor-ed with polynomial, the MSB is made zero |
shreeshas95 | 0:f016e9e8d48b | 33 | hence the first digit of the remainder is ignored in the loop |
shreeshas95 | 0:f016e9e8d48b | 34 | */ |
shreeshas95 | 0:f016e9e8d48b | 35 | } |
shreeshas95 | 0:f016e9e8d48b | 36 | else{ |
shreeshas95 | 0:f016e9e8d48b | 37 | remainder = (remainder << 1); |
shreeshas95 | 0:f016e9e8d48b | 38 | } |
shreeshas95 | 0:f016e9e8d48b | 39 | } |
shreeshas95 | 0:f016e9e8d48b | 40 | } |
shreeshas95 | 0:f016e9e8d48b | 41 | |
shreeshas95 | 0:f016e9e8d48b | 42 | return remainder; |
shreeshas95 | 0:f016e9e8d48b | 43 | } |
shreeshas95 | 0:f016e9e8d48b | 44 | |
shreeshas95 | 0:f016e9e8d48b | 45 | typedef uint8_t crctype8; |
shreeshas95 | 0:f016e9e8d48b | 46 | crctype8 crc8_gen(const unsigned char message[], unsigned int nBytes){ |
shreeshas95 | 0:f016e9e8d48b | 47 | |
shreeshas95 | 0:f016e9e8d48b | 48 | crctype8 remainder = 0xff; |
shreeshas95 | 0:f016e9e8d48b | 49 | |
shreeshas95 | 0:f016e9e8d48b | 50 | for(int byte = 0 ; byte < nBytes ; byte++ ){ |
shreeshas95 | 0:f016e9e8d48b | 51 | /* |
shreeshas95 | 0:f016e9e8d48b | 52 | Bring the data byte by byte |
shreeshas95 | 0:f016e9e8d48b | 53 | each time only one byte is brought |
shreeshas95 | 0:f016e9e8d48b | 54 | 0 xor x = x |
shreeshas95 | 0:f016e9e8d48b | 55 | */ |
shreeshas95 | 0:f016e9e8d48b | 56 | remainder = remainder ^ ( message[byte] ); |
shreeshas95 | 0:f016e9e8d48b | 57 | |
shreeshas95 | 0:f016e9e8d48b | 58 | for(int bit = 8 ; bit > 0 ; bit--){ |
shreeshas95 | 0:f016e9e8d48b | 59 | /* |
shreeshas95 | 0:f016e9e8d48b | 60 | for each bit, xor the remainder with polynomial |
shreeshas95 | 0:f016e9e8d48b | 61 | if the MSB is 1 |
shreeshas95 | 0:f016e9e8d48b | 62 | */ |
shreeshas95 | 0:f016e9e8d48b | 63 | if(remainder & TOPBIT8){ |
shreeshas95 | 0:f016e9e8d48b | 64 | remainder = (remainder << 1) ^ POLYNOMIAL8; |
shreeshas95 | 0:f016e9e8d48b | 65 | /* |
shreeshas95 | 0:f016e9e8d48b | 66 | each time the remainder is xor-ed with polynomial, the MSB is made zero |
shreeshas95 | 0:f016e9e8d48b | 67 | hence the first digit of the remainder is ignored in the loop |
shreeshas95 | 0:f016e9e8d48b | 68 | */ |
shreeshas95 | 0:f016e9e8d48b | 69 | } |
shreeshas95 | 0:f016e9e8d48b | 70 | else{ |
shreeshas95 | 0:f016e9e8d48b | 71 | remainder = (remainder << 1); |
shreeshas95 | 0:f016e9e8d48b | 72 | } |
shreeshas95 | 0:f016e9e8d48b | 73 | } |
shreeshas95 | 0:f016e9e8d48b | 74 | } |
shreeshas95 | 0:f016e9e8d48b | 75 | |
shreeshas95 | 0:f016e9e8d48b | 76 | return remainder; |
ee12b079 | 145:fb800fecf128 | 77 | } |
ee12b079 | 145:fb800fecf128 | 78 | |
ee12b079 | 145:fb800fecf128 | 79 | uint16_t crc16_gen1( char message[], unsigned int nBytes){ |
ee12b079 | 145:fb800fecf128 | 80 | crctype16 remainder = 0xffff; |
ee12b079 | 145:fb800fecf128 | 81 | int byte; |
ee12b079 | 145:fb800fecf128 | 82 | char bit; |
ee12b079 | 145:fb800fecf128 | 83 | |
ee12b079 | 145:fb800fecf128 | 84 | for( byte = 0 ; byte < nBytes ; byte++ ){ |
ee12b079 | 145:fb800fecf128 | 85 | /* |
ee12b079 | 145:fb800fecf128 | 86 | Bring the data byte by byte |
ee12b079 | 145:fb800fecf128 | 87 | each time only one byte is brought |
ee12b079 | 145:fb800fecf128 | 88 | 0 xor x = x |
ee12b079 | 145:fb800fecf128 | 89 | */ |
ee12b079 | 145:fb800fecf128 | 90 | remainder = remainder ^ ( message[byte] << 8 ); |
ee12b079 | 145:fb800fecf128 | 91 | |
ee12b079 | 145:fb800fecf128 | 92 | for( bit = 8 ; bit > 0 ; bit--){ |
ee12b079 | 145:fb800fecf128 | 93 | /* |
ee12b079 | 145:fb800fecf128 | 94 | for each bit, xor the remainder with polynomial |
ee12b079 | 145:fb800fecf128 | 95 | if the MSB is 1 |
ee12b079 | 145:fb800fecf128 | 96 | */ |
ee12b079 | 145:fb800fecf128 | 97 | if(remainder & TOPBIT16){ |
ee12b079 | 145:fb800fecf128 | 98 | remainder = (remainder << 1) ^ POLYNOMIAL16; |
ee12b079 | 145:fb800fecf128 | 99 | /* |
ee12b079 | 145:fb800fecf128 | 100 | each time the remainder is xor-ed with polynomial, the MSB is made zero |
ee12b079 | 145:fb800fecf128 | 101 | hence the first digit of the remainder is ignored in the loop |
ee12b079 | 145:fb800fecf128 | 102 | */ |
ee12b079 | 145:fb800fecf128 | 103 | } |
ee12b079 | 145:fb800fecf128 | 104 | else{ |
ee12b079 | 145:fb800fecf128 | 105 | remainder = (remainder << 1); |
ee12b079 | 145:fb800fecf128 | 106 | } |
ee12b079 | 145:fb800fecf128 | 107 | } |
ee12b079 | 145:fb800fecf128 | 108 | } |
ee12b079 | 145:fb800fecf128 | 109 | |
ee12b079 | 145:fb800fecf128 | 110 | return remainder; |
ee12b079 | 145:fb800fecf128 | 111 | } |
ee12b079 | 145:fb800fecf128 | 112 |