PHP B-tree - Add element/node

Here follows an example of creating "Multiway B-Tree".
< br />The implementation is in PHP:

// B-tree
function btree_search( $value, $a, &$higher, $v)
{
 global $tree, $q, $u, $n, $nn;
 
 static $v;
 
 // create new elelemt
 if( $tree[$a]['m'] == 0 )
 {
  $higher = true;
  $v['value'] = $value;
  $v['count'] = 1;
  $v['p'] = null;
  
  $u = $v;
 }
 else
 {
   $cur = $tree[$a];
   $l = 1;
   $r = $cur['m'];

   do// binary search
   {
    $k = (int)( ($l + $r)/2);
    if( $value <= $cur['el'][$k]['value'] )
    {
     $r = $k - 1;
    }
    if( $value >= $cur['el'][$k]['value'] )
    {
     $l = $k + 1;
    }
   }while( $r >= $l);

   // found
   if( $l - $r > 1)
   {
    $cur['el'][$k]['count']++;
    $higher = false;
   }
   else
   {
    if( $r == 0 )
     $q = $cur['p0'];
    else
     $q = $cur['el'][$r]['p'];
    
    btree_search($value, $q, $higher, $u);
    if( $higher )
    {
     /* $a !== null. Search key $value in B-tree with root $a;
       insert new item with key $value. If an entry is to be passed up,
       assign it to $v. $higher = "tree has become higher"
    */
     
     $cur = &$tree[$a];
    
     // !$higher
    if( $cur['m'] < $n*2 )
    {
     $cur['m']++;
     $higher = false;

     
     for( $i=$cur['m']; $i >= $r+2; $i-- )
     {
      $cur['el'][$i] = $cur['el'][$i-1];
      
     }
     
     $cur['el'][$r+1] = $u;
     
    }
    // page $tree[$a]/$cur is full.
    // It's partioned and the odd element is moved to v 
    else
    {
     // add new element to $tree and assign
     // the last element's num to $b;
     $b = array_push($tree, array());
     if( $r <= $n ) // insert in left page $a
     {
      if( $r == $n )
       $v = $u;
      else
      {
       $v = $cur['el'][$n];
       for( $i=$n; $i >= $r+2; $i-- )
        $cur['el'][$i] = $cur['el'][$i-1];
       
       $cur['el'][$r+1] = $u;
      }
      for( $i=1; $i <= $n; $i++ ){
       $tree[$b]['el'][$i] = $cur['el'][$i+$n];
       unset( $cur['el'][$i+$n] );
      }
     }
     else // insert into right page $b
     {
      $r = $r-$n;
      $v = $cur['el'][$n+1];
      for( $i=1; $i <= $r-1; $i++ )
       $tree[$b]['el'][$i] = $cur['el'][$i+$n+1];
      $tree[$b]['el'][$r] = $u;
       
      for( $i=$r+1; $i <= $n; $i++ )
       $tree[$b]['el'][$i] = $cur['el'][$i+$n];
      
     }
     $cur['m'] = $n;
     $tree[$b]['m'] = $n;
     $tree[$b]['p0'] = $v['p'];
     $v['p'] = $b;
     
     $u = $v;
    }
    }
   }
 }
 return 1;
}

$b_tree = array();
// you could create as many trees as you want
// but when you want to work with them use $tree = &$my_tree;
$tree = &$b_tree;
// array for B-tree insert test
// test steps bellow to see how the tree behaves 
$values = array(20);
//$values = array(20, 40, 10, 30,15);
//$values = array(20, 40, 10, 30,15, 35, 7, 26, 18, 22);
//$values = array(20, 40, 10, 30,15, 35, 7, 26, 18, 22, 5);
//$values = array(20, 40, 10, 30,15, 35, 7, 26, 18, 22, 5, 42, 13, 46, 27, 8, 32);
//$values = array(20, 40, 10, 30,15, 35, 7, 26, 18, 22, 5, 42, 13, 46, 27, 8, 32, 38, 24, 45, 25 );

$higher = false;
$root = null;
$n = 2;
foreach( $values as $val )
{

 btree_search( $val, $root, $higher, $u);
 if( $higher )
 {
  $q = $root;
  if( count($tree) == 0 )
  {
   $tree = array(1=>array());
   $root = 1;
  }
  else
   $root = array_push($tree, array());

  $tree[$root]['m'] = 1;
  $tree[$root]['p0'] = $q;
  
  $tree[$root]['el'][1] = $u;
 }
}