CRC-16/CCITT算法实现

╰半橙微兮° 2023-01-19 09:44 55阅读 0赞

1、C语言版本

#include <stdio.h>
    #include <stdlib.h>
    #include <string.h>
    
    //截取指定长度的字符串
    char* substring(char *dst,char *src,int start,int len) {
    	char *p=dst;
    	char *q=src;
    	int length=strlen(src);
    	if(start>=length||start<0)
    		return NULL;
    	if(len>length)
    		len=length-start;
    	q+=start;
    	while(len--) {
    		*(p++)=*(q++);
    	}
    	*(p++)='\0';
    	return dst;
    }
    
    //将字串转成指定数组
    char**  INIT_ARR(char *str,int t) {
    	int len=t/2;
    	printf("len: %d\n", len);
    	int i;
    	char arr[len][2];
    	for(i=0; i<len; i++) {
    		substring(arr[i],str,i*2,2);
    	}
    	printf("%s\n","init  arr  suc");
    	
    	
    	return arr;
    }
    
    //crc16 算法
    unsigned short crc16(unsigned char *arr, unsigned int len) {
    	unsigned short crc_in = 0x0000;
    	unsigned short crc_poly = 0x8408; 
    	unsigned char ch = 0;
    	unsigned char i;
    	while(len--) {
    		ch = *(arr++);
    		crc_in^=ch;
    		for(i=0; i<8; i++) {
    			if(crc_in&0x0001) {
    				crc_in=(crc_in>>1)^crc_poly;
    			} else {
    				crc_in=crc_in>>1;
    			}
    		}
    	}
    	return  (crc_in);
    }
    
    
    int main(int argc, char *argv[]) {
    	///7d7d00000001000011001c010c37452971053738363134394a0756312e302e30300000000000008efe
    	unsigned char ch[]="00000001000011001c010c37452971053738363134394a0756312e302e3030000000000000";
    	typedef unsigned char   uint8_t;
    	uint8_t arr[] = {0x00,0x00,0x00,0x01,0x00,0x00,0x11,0x00,0x1c,
    	                 0x01,0x0c,0x37,0x45,0x29,0x71,0x05,0x37,0x38,
    	                 0x36,0x31,0x34,0x39,0x4a,0x07,0x56,0x31,0x2e,
    	                 0x30,0x2e,0x30,0x30,0x00,0x00,0x00,0x00,0x00,0x00
    	                };
    	unsigned short  res = crc16(arr,sizeof(arr));
    	printf("res:%d\n",res);
    	return 0;
    }

2、java版实现

public  static   String  genCrc16(String  cmd){
            int length = cmd.length();
            assert length%2==0;
            int len = length / 2;
            String[] arr=new String[len];
            for (int i=0; i<len;i++) {
                arr[i]=cmd.substring(i*2,i*2+2);
            }
            int  wCrcIn=0x0000,wCrcPoly=0x8408,constantLen=8;
            for (String  ch : arr) {
                wCrcIn^=Integer.parseInt(ch,16);
                for(int i=0;i<constantLen;i++){
                    boolean  f= (wCrcIn & 0x0001)==1;
                    wCrcIn=f?((wCrcIn>>1)^ wCrcPoly):(wCrcIn>>1);
                }
             }
            return Integer.toHexString(wCrcIn);
        }