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Added CRC8 generating function

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dooku 2021-06-09 18:33:13 +02:00
parent 4833a4fb99
commit 9b6c86454b
2 changed files with 50 additions and 0 deletions
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22
fw/Core/Inc/crc8.h Normal file
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/*
* crc.h
*
* Created on: Jun 9, 2021
* Author: user
*/
#ifndef INC_CRC8_H_
#define INC_CRC8_H_
#include "stdint.h"
/*
* Definitions & macros
*/
#define CRC8_POLYNOMIAL 0x31
#define CRC8_INIT 0xFF
uint8_t crc8_calculate(const uint8_t *data, uint16_t count);
#endif /* INC_CRC8_H_ */

28
fw/Core/Src/crc8.c Normal file
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/*
* crc.c
*
* Created on: Jun 9, 2021
* Author: user
*/
#include "crc8.h"
/* Stolen from Sensirion SCD4x datasheet, section 3.11 */
uint8_t crc8_calculate(const uint8_t *data, uint16_t count)
{
uint16_t current_byte;
uint8_t crc = CRC8_INIT;
uint8_t crc_bit;
/* calculates 8-Bit checksum with given polynomial */
for (current_byte = 0; current_byte < count; ++current_byte) {
crc ^= (data[current_byte]);
for(crc_bit = 8; crc_bit > 0; --crc_bit) {
if (crc & 0x80) {
crc =(crc << 1) ^ CRC8_POLYNOMIAL;
} else {
crc = (crc << 1);
}
}
}
return crc;
}