/* Octal Alpha to Integer conversion */
/* ATT. ! max value: 0xfffffffe   ( -1 is returned in case of error ) */

int atox(string)
char *string;
{
   int i;
   int len = 0;
   int n = 0;
   unsigned char digit;
   
   if (*string != '0' || (*(string + 1) != 'x' && *(string + 1) != 'X') )
      return -1;
   for (i = 2; i < 11 && *(string + i ) != '\0'; i++)
      ++len;
   if (len > 8)
      return -1;      

   for (i = 2; i < len + 2 ; i++){
      switch ( *(string + i) ){
          case '0': 
                    digit = 0x0;
                    break;
          case '1': 
                    digit = 0x1;
                    break;
          case '2': 
                    digit = 0x2;
                    break;
          case '3': 
                    digit = 0x3;
                    break;
          case '4': 
                    digit = 0x4;
                    break;
          case '5': 
                    digit = 0x5;
                    break;
          case '6': 
                    digit = 0x6;
                    break;
          case '7': 
                    digit = 0x7;
                    break;
          case '8': 
                    digit = 0x8;
                    break;
          case '9': 
                    digit = 0x9;
                    break;
          case 'a': 
          case 'A': 
                    digit = 0xa;
                    break;
          case 'b': 
          case 'B': 
                    digit = 0xb;
                    break;
          case 'c': 
          case 'C': 
                    digit = 0xc;
                    break;
          case 'd': 
          case 'D': 
                    digit = 0xd;
                    break;
          case 'e': 
          case 'E': 
                    digit = 0xe;
                    break;
          case 'f': 
          case 'F': 
                    digit = 0xf;
                    break;
          default :
                    return -1;
      } 
      n |= ( digit << (len + 1 - i) * 4 );
   }
   return n;
}