FizzBuzz in Assembler (750 bytes compiled)

fizzbuzz_original.asm

.model tiny
.stack 100h
.data

	number db '00', 13, 10, '$'
	newline db 13, 10, '$'

	fizz db 'Fizz.', 13, 10, '$'
	buzz db 'Buzz.', 13, 10, '$'
	fizzbuzz db 'FizzBuzz.', 13, 10, '$'

.code

	mov ax, @data
	mov ds, ax
	mov es, ax

	; initialise counters
	mov ax, 15
	mov bx, 5
	mov cx, 3
	mov dx, 1

	start_loop:
		; decrease counters
		dec ax
		dec bx
		dec cx

		; fizz buzz hit 0? print
		cmp ax, 0
		jne test2
		jmp prt_fizzbuzz

	test2:
		; buzz hit 0? print
		cmp bx, 0
		jne test3
		jmp prt_buzz

	test3:
		; fizz hit 0? print
		cmp cx, 0
		jne print_number
		jmp prt_fizz


 	print_number:


		mov di, offset number

		; larger than 10? print two digits
		cmp dx, 10
		jge two_digits

		; otherwise add ' ' and '0'+dl
 		push ax

		mov al, ' '
		stosb

		mov al, dl
		add al, '0'
		stosb

		pop ax

		jmp print_now

	two_digits:

		push bx
		push ax

		; first digit
		mov ax, dx
		mov bl, 10
		div bl

		add al, '0'
		stosb

		mov al, ah
		add al, '0'
		stosb

		pop ax
		pop bx


	print_now:

 		push ax
 		push dx

		mov dx, offset number
		mov al, 24h
		mov ah, 09h
		int 21h

		pop dx
		pop ax


;		pop cx
;		pop bx
;		pop ax


	; after printing we end up here
	continue_loop:

		; try to reset counters if required
		cmp ax, 0
		jne cont2
		mov ax, 15

	cont2:
		cmp bx, 0
		jne cont3
		mov bx, 5

	cont3:
		cmp cx, 0
		jne cont4
		mov cx, 3

	cont4:
		
		; increase overall counter (0 -> 100)
		inc dx


		; < 101 goto loop
		cmp dx, 100
		jne start_loop


		; terminate
		mov ah, 4ch
		int 21h


	prt_fizz:


		push dx
		push ax

		mov dx, offset fizz
		mov al, 24h
		mov ah, 09h
		int 21h

		pop ax
		pop dx

		jmp continue_loop

	prt_buzz:

		push dx
		push ax

		mov dx, offset buzz
		mov al, 24h
		mov ah, 09h
		int 21h

		pop ax
		pop dx

		jmp continue_loop

	prt_fizzbuzz:

		push dx
		push ax

		mov dx, offset fizzbuzz
		mov al, 24h
		mov ah, 09h
		int 21h

		pop ax
		pop dx

		jmp continue_loop


end