Escalera en Donkey Kong

Del excelente sitio de Don Hodges aparece el algoritmo de si un barril se va ir por una escalera hacia abajo o no: http://donhodges.com/Controlling_the_barrels_in_Donkey_Kong.htm

En donde hace referencia a otro sitio con mas info: http://www.jeffsromhack.com/products/donkeykong_tech.htm

Bueno, como sea este es el snippet code:

// A barrel has reached a ladder. Decide whether or not to go down it.
// Decompiled from Z80 Assembly by Don Hodges // July, 2008

Take_ladder = false ;
If oil_fire == not_lit then {
 Take_ladder = true;
 Return ; }
End if ;
If Mario_height >= barrel_height then Return ;
R = random(255) ;   // random number between 0 and 255 inclusive
R2 = R mod 3 ;    // random number between 0 and 3 inclusive, based on R
If R2 >= ((difficulty div 2 ) + 1) then Return ;
If (barrel_x_position == Mario_x_position) or 
  ((barrel_x_position < Mario_x_position) and (joystick_direction == left)) or
  ((barrel_x_position > Mario_x_position) and (joystick_direction == right))
 then {
 Take_ladder = true;
 Return ; }
End if ;
If (R & 0x18) != 0 then Return ; // 75% chance of return without ladder
Take_ladder = true;   // 25% chance of taking ladder
Return