// Multiplier by Olivier Lecluse

%define statusRegister      252
%define buttonRegister      253
%define reslow              243
%define reshigh             244
%define n1                  240
%define n2low               241
%define n2high              242

	initsp
	copylr 63 n1         // first number
	copylr 67 n2low      // second number
	copylr 0 n2high
	copylr 0 reslow      // res (16 bits) = n1 x n2
	copylr 0 reshigh
:loop
	bcrsc 0 n1
	call addn            // adds n2 to res if n1 is odd
	cbr 1 statusRegister // Clear carry
	shiftrr n1           // shifts n1 right
	cbr 1 statusRegister // Clear carry
	shiftrl n2low        // shifts n2 left
	shiftrl n2high
	copyla 255
	andra n1             // tests if n1 is zero
	bcrss 0 statusRegister 
	jump loop
	halt
:addn			     // adds n2 to res (16 bits)
	copyra reslow 
	addra n2low          // 8 low bits
	bcrsc 1 statusRegister
	incr reshigh         // adds carry
	copyar reslow
	copyra reshigh
	addra n2high         // 8 high bits
	copyar reshigh
	return