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43 lines
1.1 KiB
43 lines
1.1 KiB
#include "crc.h"
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uint8_t crc8(uint8_t buf[], uint8_t len) {
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uint8_t crc = CRC8_INIT;
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for(uint8_t i = 0; i < len; i++) {
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crc ^= buf[i];
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for(uint8_t b = 0; b < 8; b ++) {
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crc = (crc << 1) ^ ((crc & 0x80) ? CRC8_POLY : 0x00);
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}
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}
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return crc;
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}
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uint16_t crc16(uint8_t buf[], uint8_t len) {
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uint16_t crc = 0xffff;
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uint8_t shift = 0;
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for(uint8_t i = 0; i < len; i ++) {
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crc = crc ^ buf[i];
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for(uint8_t bit = 0; bit < 8; bit ++) {
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shift = (crc & 0x0001);
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crc = crc >> 1;
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if(shift != 0)
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crc = crc ^ 0xA001;
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}
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}
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return crc;
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}
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uint16_t crc16nrf24(uint8_t buf[], uint16_t lenBits, uint16_t startBit, uint16_t crcIn) {
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uint16_t crc = crcIn;
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uint8_t idx, val = buf[(startBit >> 3)];
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for(uint16_t bit = startBit; bit < lenBits; bit ++) {
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idx = bit & 0x07;
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if(0 == idx)
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val = buf[(bit >> 3)];
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crc ^= 0x8000 & (val << (8 + idx));
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crc = (crc & 0x8000) ? ((crc << 1) ^ CRC16_NRF24_POLYNOM) : (crc << 1);
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}
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return crc;
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}
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