; quadcall.asm
;
; this program sets up the paramaters and calls
; "quadr.asm" as a subroutine.
;
; set up the stack.

        org     $0800
start:  lds     #$07ff  ;init the stack pointer

; set up the stop bit so that the "stop" instruction
; will work
        tpa
        anda    #$7f
        tap

; clear all the registers, so that when we try to
; save them on the stack, the simulator doesn't
; yell at us for tryting to use an uninitiated
; register.
        clra
        clrb
        ldx     #0
        ldy     #0

; set up the paramaters we need, and push them onto
; the stack. say a=2, b=5, c=4 and x=6

        ldaa    #!2
        psha
        ldaa    #!5
        psha
        ldaa    #!4
        psha
        ldaa    #!6
        psha

; now add some room for the return address

        pshx

; and call the subroutine

        jsr quadratic

; after the subroutine is done, the value of f(x)
; should be on the top of the stack.  let's pop it
; into "D" to look at it.

        pula
        pulb

; and for clenliness, let's empty the stack. There
; are 4 bytes left on the stack, so the easiest way
; is to pull X twice.

        pulx
        pulx

; we're done, so stop.

        stop

; now include the subroutine.

$include 'quadr.asm'

; and finally setup the reset vector
        org     $fffe
reset:  dw      start