/*
** 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<<4;
    *nbr = *nbr+(*hexstr++)-t;
    }
  return d;
  }