kopia lustrzana https://github.com/OpenRTX/OpenRTX
45 wiersze
1.0 KiB
C++
45 wiersze
1.0 KiB
C++
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#include "crc16.h"
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namespace miosix {
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/**
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* 16 bit ccitt crc calculation
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* \param crc the firs time the function is called, pass 0xffff, all the other
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* times, pass the previous value. The value returned after the last call is
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* the desired crc
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* \param data a byte of the message
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*/
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static inline void crc16Update(unsigned short& crc, unsigned char data)
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{
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unsigned short x=((crc>>8) ^ data) & 0xff;
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x^=x>>4;
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crc=(crc<<8) ^ (x<<12) ^ (x<<5) ^ x;
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}
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unsigned short crc16(const void *message, unsigned int length)
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{
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const unsigned char *m=reinterpret_cast<const unsigned char*>(message);
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unsigned short result=0xffff;
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for(unsigned int i=0;i<length;i++) crc16Update(result,m[i]);
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return result;
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}
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} //namespace miosix
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//Testcase
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/*#include <iostream>
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#include <boost/crc.hpp>
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using namespace std;
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int main()
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{
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unsigned char test[]="Some test string";
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cout<<"0x"<<hex<<miosix::crc16(test,sizeof(test))<<endl;
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boost::crc_ccitt_type crc;
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crc.process_bytes(test,sizeof(test));
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cout<<"0x"<<hex<<crc.checksum()<<endl;
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}*/
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