Mike Fruge / OneWire

Implementation of 1-Wire with added Alarm Search Functionality

Dependents:   Max32630_One_Wire_Interface

crc.cpp@78:0cbbac7f2016, 2016-05-16 (annotated)

Committer:
IanBenzMaxim
Date:
Mon May 16 15:18:09 2016 -0500
Revision:
78:0cbbac7f2016
Child:
80:83b0d879cc32
Code cleanup.

Who changed what in which revision?

UserRevisionLine numberNew contents of line
IanBenzMaxim 78:0cbbac7f2016 1 #include "crc.h"
IanBenzMaxim 78:0cbbac7f2016 2
IanBenzMaxim 78:0cbbac7f2016 3 uint16_t OneWire::crc::calculateCrc16(uint16_t crc16, uint16_t data)
IanBenzMaxim 78:0cbbac7f2016 4 {
IanBenzMaxim 78:0cbbac7f2016 5 const uint16_t oddparity[] = { 0, 1, 1, 0, 1, 0, 0, 1, 1, 0, 0, 1, 0, 1, 1, 0 };
IanBenzMaxim 78:0cbbac7f2016 6
IanBenzMaxim 78:0cbbac7f2016 7 data = (data ^ (crc16 & 0xff)) & 0xff;
IanBenzMaxim 78:0cbbac7f2016 8 crc16 >>= 8;
IanBenzMaxim 78:0cbbac7f2016 9
IanBenzMaxim 78:0cbbac7f2016 10 if (oddparity[data & 0xf] ^ oddparity[data >> 4])
IanBenzMaxim 78:0cbbac7f2016 11 {
IanBenzMaxim 78:0cbbac7f2016 12 crc16 ^= 0xc001;
IanBenzMaxim 78:0cbbac7f2016 13 }
IanBenzMaxim 78:0cbbac7f2016 14
IanBenzMaxim 78:0cbbac7f2016 15 data <<= 6;
IanBenzMaxim 78:0cbbac7f2016 16 crc16 ^= data;
IanBenzMaxim 78:0cbbac7f2016 17 data <<= 1;
IanBenzMaxim 78:0cbbac7f2016 18 crc16 ^= data;
IanBenzMaxim 78:0cbbac7f2016 19
IanBenzMaxim 78:0cbbac7f2016 20 return crc16;
IanBenzMaxim 78:0cbbac7f2016 21 }
IanBenzMaxim 78:0cbbac7f2016 22
IanBenzMaxim 78:0cbbac7f2016 23 uint16_t OneWire::crc::calculateCrc16(const uint8_t * data, size_t dataOffset, size_t dataLen, uint16_t crc)
IanBenzMaxim 78:0cbbac7f2016 24 {
IanBenzMaxim 78:0cbbac7f2016 25 for (size_t i = dataOffset; i < (dataLen + dataOffset); i++)
IanBenzMaxim 78:0cbbac7f2016 26 {
IanBenzMaxim 78:0cbbac7f2016 27 crc = calculateCrc16(crc, data[i]);
IanBenzMaxim 78:0cbbac7f2016 28 }
IanBenzMaxim 78:0cbbac7f2016 29 return crc;
IanBenzMaxim 78:0cbbac7f2016 30 }