crc_check.c

基于MSP430f149的编码与解码通信系统

#include "common.h"
#include "CRC_CHECK.h"


unsigned char crc8(unsigned char *ptr, unsigned char len)  
{ 
	unsigned char i; 
	unsigned char crc=0; 

	while(len--!=0)  
	{ 
		for(i=1; i!=0; i*=2) 
		{ 
			if((crc&1)!=0) 
			{
				crc/=2; 
				crc^=0x8C;
			}
			else 
				crc/=2; 
			if((*ptr&i)!=0) 
				crc^=0x8C;     
		}  
		ptr++; 
	} 
	return(crc); 
}


/*
//1.根据老古开发网资料，使用半字节查表的Crc16方法，适合单片机，已测试

unsigned int crc_ta[16]={ 
0x0000,0x1021,0x2042,0x3063,0x4084,0x50a5,0x60c6,0x70e7,
0x8108,0x9129,0xa14a,0xb16b,0xc18c,0xd1ad,0xe1ce,0xf1ef,
};

unsigned int Crc16(unsigned char *ptr, unsigned char len) 
{
	unsigned int crc;
	unsigned char da;

	crc=0;
	while(len--!=0)
	{
		da=crc>>12; 
		crc<<=4; 
		crc^=crc_ta[da^(*ptr/16)]; 
                              
		da=crc>>12; 
		crc<<=4; 
		crc^=crc_ta[da^(*ptr&0x0f)]; 
		ptr++;
	}
	
	return(crc);
}*/