Implementation of 1-Wire with added Alarm Search Functionality
Dependents: Max32630_One_Wire_Interface
Diff: Utilities/crc.cpp
- Revision:
- 86:2ce08ca58b9e
- Parent:
- 80:83b0d879cc32
- Child:
- 90:c233d1c265ff
diff -r 708b7be59fb2 -r 2ce08ca58b9e Utilities/crc.cpp --- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/Utilities/crc.cpp Wed Jun 15 15:00:06 2016 -0500 @@ -0,0 +1,61 @@ + + +#include "crc.h" + + +uint8_t OneWire::crc::calculateCrc8(uint8_t crc8, uint8_t data) +{ + // See Application Note 27 + crc8 = crc8 ^ data; + for (int i = 0; i < 8; i++) + { + if (crc8 & 1) + { + crc8 = (crc8 >> 1) ^ 0x8c; + } + else + { + crc8 = (crc8 >> 1); + } + } + + return crc8; +} + +uint8_t OneWire::crc::calculateCrc8(const uint8_t * data, size_t dataLen, uint8_t crc) +{ + for (size_t i = 0; i < dataLen; i++) + { + crc = calculateCrc8(crc, data[i]); + } + return crc; +} + +uint16_t OneWire::crc::calculateCrc16(uint16_t crc16, uint16_t data) +{ + const uint16_t oddparity[] = { 0, 1, 1, 0, 1, 0, 0, 1, 1, 0, 0, 1, 0, 1, 1, 0 }; + + data = (data ^ (crc16 & 0xff)) & 0xff; + crc16 >>= 8; + + if (oddparity[data & 0xf] ^ oddparity[data >> 4]) + { + crc16 ^= 0xc001; + } + + data <<= 6; + crc16 ^= data; + data <<= 1; + crc16 ^= data; + + return crc16; +} + +uint16_t OneWire::crc::calculateCrc16(const uint8_t * data, size_t dataOffset, size_t dataLen, uint16_t crc) +{ + for (size_t i = dataOffset; i < (dataLen + dataOffset); i++) + { + crc = calculateCrc16(crc, data[i]); + } + return crc; +}