<!-- lang: java -->/*** made by wangming * * 2013-10-28  pm*/package wang.ming.data;public class Analysis {//生成海明码  public static int[] HaiMingMa(int original[],int len ){int checkBits=length(len);    //计算需要多长的校验码
int size=len+checkBits;        //发送的数据长度
int send[]=new int[size];
int o_s=0;   //original当前的偏移量//初始化
for(int i=0;i<size;i++){if(canFit(i+1, checkBits)){send[i]=original[o_s];o_s++;}else {send[i]=0;}
}for(int i=0;i<checkBits;i++){int fill=0;for(int j=1;j<=size;j++){if(canFit(j, checkBits)){if(in(j, i, checkBits)){fill=XOR(fill, send[j-1]);}}}int id=(int)Math.pow(2, (double)i);send[id-1]=fill;
}
return send;}/** 接受海明码  并进行处理*/public static int[]receive(int send[]){int size=send.length;int bits=codeLength(size);int errorBit=check(send, bits,size);int []receive = new int[size-bits];if(errorBit>0){System.out.println("第"+errorBit+"出错了");}if(!canFit(errorBit, bits)){System.out.println("出错的是校验码，不影响结果");}int index=0;for(int i=0;i<size;i++){if(canFit(i+1, bits)){if((i+1)!=errorBit){receive[index]=send[i];}else{receive[index]=XOR(send[i], 1);//对出错的地方进行处理   与1异或即可得到原来的值}index++;}}return  receive;}/** 判断接受的海明码是否出错*/public static int check(int receive[],int bits,int size){int errorBit=0;for(int j=0;j<bits;j++){int flag=0;for(int i=0;i<size;i++){if(canFit(i+1, bits)){if(in(i+1, j, bits)){flag=XOR(flag, receive[i]);}}}int index=(int)Math.pow(2, (double)j)-1;flag=XOR(flag, receive[index]);if(flag==1){errorBit+=(int)Math.pow(2, (double)j);}}return errorBit;}/** x=a*(2*2...*2)+b*(2*2...*2)+...+c*2+d*     [-bits-1-]   [-bits-2-]      *     其中常数a,b,c..等于0，1*     如果 2的y次方前的常数为1   return true*     为0   return false */public static boolean in(int x,int y,int bits){int dive[]=new int[bits];int index=0;for(int i=bits-1;i>=0;i--){if(x/(int)Math.pow(2, (double)i)>0){dive[index]=1;}else{dive[index]=0;}x=x%(int)Math.pow(2, (double)i);index++;}if(dive[bits-y-1]==1){return true;}return false;}/** 对两个数做异或操作* 相等   return 0* 否则   return 1*/public static int XOR(int x,int y){if((x-y)==0){return 0; }else{return 1;}}/** 返回 true   or   false* 如果index是2的n次方   false* 否则  true*/public static boolean canFit(int index,int checkBits){for(int i=0;i<checkBits;i++){if(index==Math.pow(2, (double)i)){return false;}}return true;}/** 由海明码反向推出校验码位数*/public static int codeLength(int len){int num=0;while((++num)>0){//逆向判断if((double)(len)<=Math.pow(2, (double)num)){return num;} if(num>20){return -1;}}return -1;}/*  给定需要传输的原始数据*  返回需要的校验码的位数*  len+x+1<=(2*2*2....*2)   *        [-----x-----]*/public static int  length(int len){int num=0;while((++num)>0){//校验码位数的判断条件if((double)(num+len+1)<=Math.pow(2, (double)num)){return num;}    if(num>20){return -1;}}return -1;}public static void main(String[] args) {System.out.println( Analysis.in(1, 0, 4));int code[]={1,0,1,1,0};int receive[]= Analysis.HaiMingMa(code, 5);receive[6]=0;System.out.println(Analysis.check(receive, 4,9));int recovery[]=Analysis.receive(receive);for(int i=0;i<recovery.length;i++ ){System.out.print(recovery[i]);}}}