Implementation of 1-Wire with added Alarm Search Functionality
Dependents: Max32630_One_Wire_Interface
Utilities/crc.cpp@90:c233d1c265ff, 2016-06-17 (annotated)
- Committer:
- IanBenzMaxim
- Date:
- Fri Jun 17 15:24:37 2016 -0500
- Revision:
- 90:c233d1c265ff
- Parent:
- 86:2ce08ca58b9e
- Child:
- 104:3f48daed532b
Moved ROM utility functions outside of the OneWireMaster class.
Who changed what in which revision?
User | Revision | Line number | New contents of line |
---|---|---|---|
IanBenzMaxim | 78:0cbbac7f2016 | 1 | #include "crc.h" |
IanBenzMaxim | 78:0cbbac7f2016 | 2 | |
IanBenzMaxim | 90:c233d1c265ff | 3 | namespace OneWire |
j3 | 80:83b0d879cc32 | 4 | { |
IanBenzMaxim | 90:c233d1c265ff | 5 | namespace crc |
j3 | 80:83b0d879cc32 | 6 | { |
IanBenzMaxim | 90:c233d1c265ff | 7 | uint8_t calculateCrc8(uint8_t crc8, uint8_t data) |
j3 | 80:83b0d879cc32 | 8 | { |
IanBenzMaxim | 90:c233d1c265ff | 9 | // See Application Note 27 |
IanBenzMaxim | 90:c233d1c265ff | 10 | crc8 = crc8 ^ data; |
IanBenzMaxim | 90:c233d1c265ff | 11 | for (int i = 0; i < 8; i++) |
IanBenzMaxim | 90:c233d1c265ff | 12 | { |
IanBenzMaxim | 90:c233d1c265ff | 13 | if (crc8 & 1) |
IanBenzMaxim | 90:c233d1c265ff | 14 | { |
IanBenzMaxim | 90:c233d1c265ff | 15 | crc8 = (crc8 >> 1) ^ 0x8c; |
IanBenzMaxim | 90:c233d1c265ff | 16 | } |
IanBenzMaxim | 90:c233d1c265ff | 17 | else |
IanBenzMaxim | 90:c233d1c265ff | 18 | { |
IanBenzMaxim | 90:c233d1c265ff | 19 | crc8 = (crc8 >> 1); |
IanBenzMaxim | 90:c233d1c265ff | 20 | } |
IanBenzMaxim | 90:c233d1c265ff | 21 | } |
IanBenzMaxim | 90:c233d1c265ff | 22 | |
IanBenzMaxim | 90:c233d1c265ff | 23 | return crc8; |
IanBenzMaxim | 90:c233d1c265ff | 24 | } |
IanBenzMaxim | 90:c233d1c265ff | 25 | |
IanBenzMaxim | 90:c233d1c265ff | 26 | uint8_t calculateCrc8(const uint8_t * data, size_t dataLen, uint8_t crc) |
IanBenzMaxim | 90:c233d1c265ff | 27 | { |
IanBenzMaxim | 90:c233d1c265ff | 28 | for (size_t i = 0; i < dataLen; i++) |
IanBenzMaxim | 90:c233d1c265ff | 29 | { |
IanBenzMaxim | 90:c233d1c265ff | 30 | crc = calculateCrc8(crc, data[i]); |
IanBenzMaxim | 90:c233d1c265ff | 31 | } |
IanBenzMaxim | 90:c233d1c265ff | 32 | return crc; |
j3 | 80:83b0d879cc32 | 33 | } |
IanBenzMaxim | 90:c233d1c265ff | 34 | |
IanBenzMaxim | 90:c233d1c265ff | 35 | uint16_t calculateCrc16(uint16_t crc16, uint16_t data) |
j3 | 80:83b0d879cc32 | 36 | { |
IanBenzMaxim | 90:c233d1c265ff | 37 | const uint16_t oddparity[] = { 0, 1, 1, 0, 1, 0, 0, 1, 1, 0, 0, 1, 0, 1, 1, 0 }; |
IanBenzMaxim | 90:c233d1c265ff | 38 | |
IanBenzMaxim | 90:c233d1c265ff | 39 | data = (data ^ (crc16 & 0xff)) & 0xff; |
IanBenzMaxim | 90:c233d1c265ff | 40 | crc16 >>= 8; |
IanBenzMaxim | 90:c233d1c265ff | 41 | |
IanBenzMaxim | 90:c233d1c265ff | 42 | if (oddparity[data & 0xf] ^ oddparity[data >> 4]) |
IanBenzMaxim | 90:c233d1c265ff | 43 | { |
IanBenzMaxim | 90:c233d1c265ff | 44 | crc16 ^= 0xc001; |
IanBenzMaxim | 90:c233d1c265ff | 45 | } |
IanBenzMaxim | 90:c233d1c265ff | 46 | |
IanBenzMaxim | 90:c233d1c265ff | 47 | data <<= 6; |
IanBenzMaxim | 90:c233d1c265ff | 48 | crc16 ^= data; |
IanBenzMaxim | 90:c233d1c265ff | 49 | data <<= 1; |
IanBenzMaxim | 90:c233d1c265ff | 50 | crc16 ^= data; |
IanBenzMaxim | 90:c233d1c265ff | 51 | |
IanBenzMaxim | 90:c233d1c265ff | 52 | return crc16; |
IanBenzMaxim | 90:c233d1c265ff | 53 | } |
IanBenzMaxim | 90:c233d1c265ff | 54 | |
IanBenzMaxim | 90:c233d1c265ff | 55 | uint16_t calculateCrc16(const uint8_t * data, size_t dataOffset, size_t dataLen, uint16_t crc) |
IanBenzMaxim | 90:c233d1c265ff | 56 | { |
IanBenzMaxim | 90:c233d1c265ff | 57 | for (size_t i = dataOffset; i < (dataLen + dataOffset); i++) |
IanBenzMaxim | 90:c233d1c265ff | 58 | { |
IanBenzMaxim | 90:c233d1c265ff | 59 | crc = calculateCrc16(crc, data[i]); |
IanBenzMaxim | 90:c233d1c265ff | 60 | } |
IanBenzMaxim | 90:c233d1c265ff | 61 | return crc; |
j3 | 80:83b0d879cc32 | 62 | } |
j3 | 80:83b0d879cc32 | 63 | } |
j3 | 80:83b0d879cc32 | 64 | } |