#include <stdio_h>
/*
** xtoi -- convert hex string to integer nbr
**         returns field size, else ERR on error
*/
xtoi(hexstr, nbr) char *hexstr; int *nbr; {
  int d, t; d=0;
  *nbr=0;
  while(1)
    {
    if ((*hexstr>='0')&(*hexstr<='9')) t=48;
    else if ((*hexstr>='A')&(*hexstr<='F')) t=55;
    else if ((*hexstr>='a')&(*hexstr<='f')) t=87;
    else break;
    if (d<4) ++d; else return ERR;
    *nbr=*nbr+(*hexstr++)-t;
  }
  return d;
}