/***This is an simple example program of convolutional encoder.    *The information sequence, the register initial states and the generation sequence    *    can all be modified in the main function.    */ #include<stdio.h> #define LEN(array, len){len=sizeof(array)/sizeof(array[0]);}//Size of array int encoder(int **gen, int n, int L, int reg[], int m, int inf[], int inf_len, int output[]) /*encoder(int **gen, int n, int L, int reg[], int m, int inf[], int inf_len, int output[])         *This function is a convolutional encoder.         *gen     is the generation sequence, which is a two-dimension array,          and it is a two-dimension pointer,         *n       is the number of bits out the encoder at each clock cycle,         *L       is for the constraight length,         *reg     is for the shift registers,         *m       is for the number of registers,         *inf     is for the information sequence,         *inf_len is for the inf length,         *output  is for the output code. */ {  int inf_ex[inf_len + m];  int i,j;//Index  for (i=0;i < inf_len + m;i++)//Extend the information sequence to include the last m bits  {   if(i < inf_len)    inf_ex[i] = inf[i];   else    inf_ex[i] = 0;  }  for (i=0;i < inf_len + m;i++)//Foreach bit in extend information  {   for (j=0;j < n;j++)//Output n bits at each clock cycle   {       int out_tem=0;//Temp number    if (*(gen + L*j) == 1)//Judge whether the next information bit should paticipate in the Mod op                 out_tem += inf_ex[i];    int k;    for (k=0;k < m;k++)//Foreach registers    {     if (*(gen + L*j + k + 1) == 1)      out_tem += reg[k];//Mod op according to the generation sequence    }    out_tem %= 2;//Mod 2    output[i*n + j] = out_tem;   }   for (j=m - 1;j > 0;j--)//Register shift   {    reg[j] = reg[j - 1];   }   reg[0] = inf_ex[i];//Input information bits into register  }  return 1; } main() {  int inf[]={1, 0, 0, 1, 1, 0, 1, 0, 1, 1, 1, 1, 1, 1, 0, 0};//Information sequence  int inf_len;//Information length  LEN(inf, inf_len);  int gen[2][7]={{1, 0, 1, 1, 0, 1, 1}, {1, 1, 1, 1, 0, 0, 1}};//Generation sequence  int n;//The number of bits out the encoder at each clock cycle  int L;//Constraight length  LEN(gen, n);  LEN(gen[0], L);  int m=L - 1;//The number of shift registers  int init_s[]={0, 0, 0, 0, 0, 0}; //Initial states are all zero  int reg[m];//Register  int i;//Index  for (i=0;i < m;i++)     {         reg[i] = init_s[i];     }  int output_len=(inf_len + m)*n;//Output length, every bit of input can generate n bits of output sequence  int output[(inf_len + m)*n];//Output sequence  encoder(gen, n, L, reg, m, inf, inf_len, output);//Encoder  for (i=0;i < output_len;i++)  {   printf("%d", output[i]);  }  system("pause"); }