#include <stdio.h>
#include <ctype.h>
#include <string.h>
main( )
{
  FILE *ifp;
  char line[100],c4[5];
  int crc[16], crcold[16], i, j, k, l, dbit, m[256] = {0};
  ifp = fopen("crc_in.txt","r");
  if (!ifp) {
    printf("crc_simin: Cannot open input file crc_in.txt %s\n");
    exit(1);
  }
  l = 0;
  //  printf("start read\n");
  while ( fgets(line, 100, ifp) != NULL) {
    int length;
    //find the length of the line
    length = strlen(line);
    for(i = 0; i < length; i++)
      //remove space
      if(line[i] == ' '){
	for(j = i; j < length; j++)
	  line[j] = line[j+1];
	length--;
      }
    for(i = 0; i < 16; i++){
      strncpy(c4,line+(5+i*4),4);
      c4[4] = '\0';
      sscanf(c4,"%x",&k);
      m[l*16+i] = k;
      //      printf("%04x",m[l*16+i]);
    }
    //    printf("\n");
    l++;
  }
  //  printf("input done\n");
  for(i=0;i<256;i+=2){
    j = m[i];
    m[i] = m[i+1];
    m[i+1] = j;
  }
  for(i=0;i<16;i++)
    crcold[i] = 1;
  //  for(i = 1; i <  233; i++){
  for(i = 1; i <  233; i++){
    for(j = 0; j < 16; j++){
      if(m[i] & 0x8000)
	dbit = 1;
      else
	dbit = 0;
      m[i] = m[i] << 1;
      crc[0] = (crcold[15] + dbit)%2;
      crc[1] = crcold[0];
      crc[2] = (crcold[15] + crcold[1]+dbit)%2;
      for(k = 3; k <15 ; k++)
	crc[k] = crcold[k-1];
      crc[15] = (crcold[15] + crcold[14]+dbit)%2;
      for(k = 0; k <16 ; k++)
	crcold[k] = crc[k];
    }
  }
  k = 0;
  for(l = 0; l <16 ; l++)
    if(crc[l])
      k += (1 << l);
  printf("crc attached = %04x, crc calculated = %04x\n",m[233],k);
  fclose(ifp);
}