local fn Doubled( n as long ) : end fn = n * 2
local fn Halved(  n as long ) : end fn = int( n / 2 )
local fn IsEven(  n as long ) : end fn = ( n mod 2 ) - 1

local fn EthiopianMultiply( x as long, y as long )
  long sum = 0, sign = x
  printf @"Ethiopian multiplication of %3ld x %3ld = \b", x, y
  do
    if not ( fn IsEven( x ) ) then sum += y
    x = fn Halved( x ) : y = fn Doubled( y )
  until ( x == 0 )
  if sign < 0 then sum *= - 1
  printf @"%4ld", sum
end fn

fn EthiopianMultiply(  17,  34 )
fn EthiopianMultiply( -17,  34 )
fn EthiopianMultiply( -17, -34 )

HandleEvents