www.pudn.com > fec_code_decode.rar > code-decode.cpp, change:2006-07-19,size:2472b

 
#include "stdio.h" 
 
void main() 
{   
	int code_in; 
	int i,j,a; 
	int code_out[15]; 
	int mid[15]; 
 
/*  code  */ 
	int g[15]={0x1,0x2,0x4,0x8,0x10,0x20,0x40,0x80,0x100,0x200,0x365,0x1AF,0x35E,0x1D9,0x3B2}; 
 
	printf("输入原始信息数据(16进制):"); 
	scanf("%x",&code_in); 
 
	for(i=0;i<15;i++) 
	{ 
		a=code_in&g[i]; 
		for(j=0;j<10;j++) 
		{ 
			mid[j]=a&1; 
			a=a>>1; 
		} 
		code_out[i]=mid[0]; 
		for(j=1;j<10;j++) 
			code_out[i]=code_out[i]^mid[j]; 
	} 
 
	printf("纠错编码后的输出比特流： "); 
	for(i=15;i>0;i--) 
		printf("%d",code_out[i-1]); 
 
/* decode and correct */   
	for (i=0;i<15;i++) 
	{  
		code_out[i]=0; 
		mid[i]=0; 
	} 
	code_in=0; 
	i=0; 
	j=0; 
	a=0; 
   
	int check_out[5]; 
	int errorflag,matchbit,matchflag,comparebit; 
	int check[5]={0x765,0x9AF,0x135E,0x21D9,0x43B2};  /*the check array*/ 
 
	printf("\n输入接受端收到的原始数据(16进制):"); 
	scanf("%x",&code_in);    /*input the data received at the receiver*/ 
 
	a=code_in; 
	for (i=0;i<15;i++)      /*change the data received into bits*/ 
	{  
		code_out[i]=a&1; 
		a=a>>1; 
	} 
 
	for(i=0;i<5;i++)        /*caculate the cheksum*/ 
	{   
		a=code_in&check[i]; 
		for(j=0;j<15;j++)    /*get every bit of a */ 
		{ 
			mid[j]=a&1; 
			a=a>>1; 
		} 
		check_out[i]=mid[0]; 
		for(j=1;j<15;j++) 
			check_out[i]=check_out[i]^mid[j]; /*add the bits in mode 2*/ 
	} 
 
	i=0;  
	errorflag=0; 
	do  
	{ 
		if (check_out[i]==1)  
		{  
			errorflag=1;  
			i=5; 
		} 
		else  
			i++; 
	} 
	while (i<5);     /* check if the check is all 0 */ 
 
	if (errorflag==1) 
	{    
		i=0;   
		matchbit=100;      /* look for the same line*/ 
		do   
		{  
			j=0;  
			matchflag=1; 
			do  
			{  
				comparebit=(check[j]>>i)&1; /* get the [j][i] bit of the array*/ 
	    		if (check_out[j]!=comparebit)  
				{ 
					j=5; 
					matchflag=0; 
				}                /*not coincident,jump out at once*/ 
				else  
					j++; 
			}  
			while (j<5); 
	        
			if (matchflag==1)  
			{ 
				matchbit=i; 
				i=15; 
			}               /*if found,jump out at once*/ 
			else  
				i++; 
		} 
		while (i<15); 
      
		if (matchbit=14) 
		{ 
			code_out[matchbit]=code_out[matchbit]^1;    /*correct the error bit*/ 
			printf("第%d位数据出错!\n",matchbit+1); 
		} 
		else  
			printf("错误但不可纠!\n"); 
	} 
	else printf("传输正确或错误不可检!\n"); 
 
	printf("还原的信息比特为:"); 
	for (i=10;i>0;i--)                     /*only print the information bits*/ 
		printf("%d",code_out[i-1]); 
}