MASM_x64_stack_test

; MASM x64 program to add five integers

.code

; adds the first five bytes on the stack, and then returns the value in the al register.
addFiveBytes PROC
	push rbp
	mov rbp, rsp ; starting f's frame
	
	; we start at 16 because when the function is called the return address is pushed to the stack,
	; then after that rbp is pushed to the stack. - each of which are 8 bytes.

	mov al, 0

	add al, [rbp + 16]
	add al, [rbp + 17]
	add al, [rbp + 18]
	add al, [rbp + 19]
	add al, [rbp + 20]
	
	mov rsp, rbp ; clean f's stack frame
	pop rbp
	ret

addFiveBytes ENDP



main PROC
	sub rsp, 1            ; Allocate a byte on the stack
	mov byte ptr [rsp], 5 ; store num1 into rsp

	sub rsp, 1
	mov byte ptr [rsp], 5 ; num 2

	sub rsp, 1
	mov byte ptr [rsp], 5 ; num 3

	sub rsp, 1
	mov byte ptr [rsp], 4 ; num 4

	sub rsp, 1
	mov byte ptr [rsp], 4 ; num 5

	
	call addFiveBytes
	; 5+5+5+4+4 = 17 in hex, or 23 in base 10


    add rsp, 5 ; cleanup the 5 values in the stack

	ret
	main ENDP
END