<?php

function get_unit($db,$param) {

  $qug = $db -> prepare(
    'select u.id,u.unit_group from st_parameters st,units u where st.id='.$param.' and st.st_unit=u.id'
  );
  $qug -> execute();
                                    
  while ($row = $qug -> fetch(PDO::FETCH_ASSOC)) {
    $from_unit = $row['id'];
    $unit_group = $row['unit_group'];
  }
                                                                       
  if (!empty($_COOKIE['unit_'.$unit_group])) {
    $to_unit=intval($_COOKIE['unit_'.$unit_group]);
  } else {
    $to_unit=$from_unit;
  }
                                                                                                                
  $qu = $db -> prepare(
    'select u.name_short from units u where u.id='.$to_unit
  );
  $qu -> execute();
                                                                                                                                                                 
  while ($row = $qu -> fetch(PDO::FETCH_ASSOC)) {
    $param_unit = $row['name_short'];
  }
 
  return Array(
    'from' => $from_unit,
    'to' => $to_unit,
    'name' => $param_unit
  );                                                                                                                                                                                    

}

function convert_unit($db,$value,$from,$to) {

  if ($from==$to) {

    $val = $value;

  } else {

    $qv = $db -> prepare(
      'select round(unitconv('.$value.','.$from.','.$to.'),2) res'
    );
    $qv -> execute();
                            
    while ($row = $qv -> fetch(PDO::FETCH_ASSOC)) {
      $val = $row['res'];
    }

  }
                                                        
  return $val;

}

?>