#include <stdio.h>
#include <conio.h>
#include <stdlib.h>
#include <time.h>
#define BYTE unsigned char
unsigned short UpdateCrc(unsigned char ch, unsigned short *lpwCrc)
{
ch = (ch^(unsigned char)((*lpwCrc) & 0x00FF));
ch = (ch^(ch<<4));
*lpwCrc = (*lpwCrc >> 8)^((unsigned short)ch << 8)^((unsigned
short)ch<<3)^((unsigned short)ch>>4);
return(*lpwCrc);
}
void ComputeCrc(unsigned short wCrcPreset, unsigned char *Data, int
Length, unsigned short &usCRC)
{
unsigned char chBlock;
do {
chBlock = *Data++;
UpdateCrc(chBlock, &wCrcPreset);
} while (--Length);
usCRC = wCrcPreset;
return;
}
void Convert7ByteUIDTo4ByteNUID(unsigned char *uc7ByteUID, unsigned char
*uc4ByteUID)
{
unsigned short CRCPreset = 0x6363;
unsigned short CRCCalculated = 0x0000;
ComputeCrc(CRCPreset, uc7ByteUID, 3,CRCCalculated);
uc4ByteUID[0] = (CRCCalculated >>8)&0xFF;//MSB
uc4ByteUID[1] = CRCCalculated &0xFF; //LSB
CRCPreset = CRCCalculated;
ComputeCrc(CRCPreset, uc7ByteUID+3, 4,CRCCalculated);
uc4ByteUID[2] = (CRCCalculated >>8)&0xFF;//MSB
uc4ByteUID[3] = CRCCalculated &0xFF; //LSB
uc4ByteUID[0] = uc4ByteUID[0]|0x0F;
uc4ByteUID[0] = uc4ByteUID[0]& 0xEF;
}
int main(void)
{
int i;
unsigned char uc7ByteUID[7] =
{0x04,0x62,0x94,0x5A,0xF4,0x64,0x80};//4F505D7D
unsigned char uc4ByteUID[4] = {0x00};
Convert7ByteUIDTo4ByteNUID(uc7ByteUID,uc4ByteUID);
printf("7-byte UID = ");
for(i = 0;i<7;i++)
printf("%02X",uc7ByteUID[i]);
printf("\t4-byte FNUID = ");
for(i = 0;i<4;i++)
printf("%02X",uc4ByteUID[i]);
getch();
return(0);
}
