63 lines
1.3 KiB
C++
63 lines
1.3 KiB
C++
#include <onewire.h>
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#include <inttypes.h>
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#include "mbed.h"
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#ifdef __cplusplus
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extern "C" {
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#endif
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#define CRC16INIT 0x0000
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//#define CRC16POLY 0x8005; // Polynome =x^16 + x^15 + x^2 + x^0 = 0x18005
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#define CRC16POLY 0xA001;
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uint16_t crc16(uint8_t* octets, uint16_t nboctets)
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{
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uint16_t crc = CRC16INIT;
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int i, done = 0;
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uint8_t todo;
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if (nboctets != 0) {
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do {
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todo = octets[done];
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crc ^= todo;
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for (i = 0; i < 8; i++) {
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if (crc % 2 != 0) {
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crc = (crc >> 1) ^ CRC16POLY;
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} else {
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crc = crc >> 1;
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}
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}
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done++;
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} while (done < nboctets);
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}
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return crc;
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}
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//CRC16 byte, always two bytes, bit inverted, LSByte first
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uint8_t ctrl_crc16(uint8_t* octets, uint16_t nboctets)
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{
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uint16_t crc;
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uint8_t *ptr;
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#ifdef DEBUG
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printf( "\nCRC16 : " );
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for ( uint8_t i=0 ; i< nboctets; i++ )
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printf(":%2.2X",octets[i]);
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printf( "\n" );
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#endif
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crc =~crc16(octets, nboctets-2);
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ptr=(uint8_t*)&crc;
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#ifdef DEBUG
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printf( "\n" );
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printf("CRC16:%X",crc);
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printf( "\n" );
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#endif
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if(*ptr==octets[nboctets-2])
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if(*++ptr==octets[nboctets-1])
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return 0;
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return 1;
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}
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}
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