; trapmain.asm
;
; this file contains the shell for setting up the
; stack with paramaters for running the "traparea"
; subroutine.

; first task is the general setup:
; set up the stack and init the registers.

        org     $3000
start:  lds     #$2fff  ;init the stack pointer
        ldy     #0
        ldx     #0
        ldd     #0

; Set up the stack by pushing the paramaters onto
; the stack in order, then calling the subroutine.

        ldaa    parama
        psha
        ldaa    paramb
        psha
        ldaa    paramh
        psha
        pshx            ; two bytes for the result

        jsr     traparea

; when we return from the subroutine, pop off the
; result and store it in "result", then clear the
; stack.

        pulx
        stx     result
        pula
        pula
        pula

; we're done, set up the stop bit and stop.
done:   tpa
        anda    #$7f
        tap
        stop

; at this point, load the subroutine

$INCLUDE        'a6q2.asm'

; here's the data area

        org     $0000
parama  db      !85
paramb  db      !30
paramh  db      !16
result  dw      !0

; result should be 0.5*16(85+30)
;                = 8(115)
;                = 184 = 0398h

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