gistfile1.php

/**
 * the normally used way to add different types in a function
 *
 * @param $nr1 - the first summand
 * @param $nr2 - the second summand
 * @param $type - the number type. default='decimal'
 */
function add_classical($nr1, $nr2, $type='decimal'){
  $sum = NULL;
  switch($type){
  case 'decimal':
    $sum = (int)$nr1 + (int)$nr2;
  case 'binary':
    $sum = bindec($nr1) + bindec($nr2);
  }
  return $sum;
}


/**
 * adds 2 numbers using the finite-state machine
 *
 * @param string $nr1 - the first summand
 * @param string $nr2 - the second summand
 * @param string $type - the number type. default='decimal'
 */
function add_ddp($nr1, $nr2,$type="decimal"){
  //put it in a machine readable format
  $list = chain($nr1, $nr2);
  //let the machine work
  return configure('wo',$list,$type);
}

/**
 * creates the fs-machines action beginning with a configuration.
 * will echo all configurations happening during its work.
 * works recursively, so don't overdo it with this function.
 *
 * @param string $state - 'w' or 'wo'
 * @param string $list - the list of entry signals
 * @return resultstring
 */
function configure($state, $list,$type="decimal"){
  echo "<br>//configure($state,".print_r($list,1).")";
  if(count($list) <= 0){ echo "=>".print_r(array(),1);return '';}
  $i = count($list)-1;
  $c1 = $list[$i][0];
  $c2 = $list[$i][1];
  $res = query($c1, $c2, $state,$type);
  unset($list[$i]);
  reset($list);
  echo "=>".print_r($res,1);
  return configure($res['nextstate'],$list,$type).$res['output'];
}

/**
 * takes two numbers as strings and forms a list of strings in the format
 * accepted by the fs-machine
 * example: chain('123','456')=>['14','25','36']
*
 * @param string nr1 - the first number as string
 * @param string nr2 - the second number as string
 * @return array
 */
function chain($nr1, $nr2){
  $list = array();
  for($y=0; $y < strlen($nr2); $y++){
    $list[] = $nr1[$y].$nr2[$y];
  }
  return $list;
}


/**
 * querys state and output for 2 numbers and a state
 * 
 * @param string $c1 - the first number
 * @param string $c2 - the second number
 * @param string $state - 'w' or 'wo' depending on the result of the last query,
                          default is 'wo' because most fs-machines begin in this state
 * @param string $type - number type that should be worked on. default='decimal'
 * @return array
 */
function query($c1, $c2, $state="wo", $type="decimal"){
  // security measures
  $c1 = mysql_real_escape_string($c1);
  $c2 = mysql_real_escape_string($c2);
  $state = mysql_real_escape_string($state);
  $type = mysql_real_escape_string($type);
  // database request
  $db = mysql_pconnect("localhost","root","root");
  mysql_select_db("ddpadd", $db);
  $sql  = "SELECT output_$state, nextstate_$state FROM ".$type."_add\n";
  $sql .= "WHERE no1='$c1' AND no2='$c2'";
  $result = mysql_query($sql, $db);
  if(!$result) throw new Exception(mysql_error($db));
  $retval = array();
  while($row = mysql_fetch_array($result)){
    $retval[] = array("output"=>$row[0],"nextstate"=>$row[1]);
  }
  return $retval[0];
}

echo "<br>classical 123 + 321 = ".add_classical('123','321');
echo "<br>finite state machine 123 + 321 = ".add_ddp('123','321');
echo "<br>add 2 binarys wih finite state machine 0101 + 0110 = ".add_ddp('0101', '0110','binary');
?>