###########################################
#
#  A modular stack data structure using
#  a v0-based calling convention.
#  This approach reserves a dedicated
#  register for a stack pointer and as
#  a result is very simple and fast.
#  maximum stack size is 256 bytes.
#
###########################################

:alias stack-ptr vd
: stack 0 0 0 0 0 0 0 0

: push
	i := stack
	i += stack-ptr
	save v0
	stack-ptr += 1
;

: pop
	stack-ptr += -1
	i := stack
	i += stack-ptr
	load v0
;

###########################################
#
#  Usage Example:
#
###########################################

: print
	# takes an arg in v0	
	i := hex v0
	sprite va vb 5
	va += 6
;

: main
	va := 3
	vb := 3

	v0 := 5 push
	v0 := 3 push
	v0 := 1 push
	pop print
	v0 := 9 push
	pop print
	pop print
	pop print

	# should print '1935'