.makeexe

	jump	main

// function fff(n)
// { local s1=0, s2=0, s3=0;
//   if (n>0)
//     s1 = fff(n-1);
//   s2 = n;
//   print n as single digit
//   if (n>1)
//     s3 = fff(n/2);
//   return s1+s2+s3; }

// n is 1st (only) parameter: FP+2
// s1 is 1st local: FP-1
// s2 is 2nd local: FP-2
// s3 is 3rd local: FP-3

fff:
// standard function entry code
	push	fp
	store	sp, fp
	sub	sp, 3

// s1=0;
	load	r1, 0
	store	r1, [fp-1]
// s2=0;
	load	r1, 0
	store	r1, [fp-2]
// s3=0;
	load	r1, 0
	store	r1, [fp-3]
// if (n>0) s1=fff(n-1)
//   if n<=0 skip over next to skip1
	compz	[fp+2]
	jcond	leq, skip1
//   s1=fff(n-1)
    	load	r1, [fp+2]
	sub	r1, 1
	push	r1
	call	fff
	add	sp, 1
	store	r1, [fp-1]
skip1:
//	s2=n;
	load	r1, [fp+2]
	store	r1, [fp-2]
//	print n as digit
	load	r1, [fp+2]
	add	r1, '0'
	type	r1
// if (n>1) s3=fff(n/2)
//   if n<=1 skip over next to skip2
	load	r1, [fp+2]
	comp	r1, 1
	jcond	leq, skip2
//   s3=fff(n/2)
	load	r1, [fp+2]
	div	r1, 2
	push	r1
	call	fff
	add	sp, 1
	store	r1, [fp-3]
skip2:
// return s1+s2+s3;
	load	r1, [fp-1]
	add	r1, [fp-2]
	add	r1, [fp-3]

// standard function exit code
	load	sp, fp
	pop	fp
	ret

main:
// fff(4);
	push	4
	call	fff
	add	sp, 1

// put result in r9 just so it stands out
	load	r9, r1
	halt