; Atari 5200 "how long to show the picture" epilogue (no OS, pure hardware).
; Selected at assembly time by WAITMODE (set by a5200/viewer/assemble.py):
;   0  forever       -- just loop
;   1  until a button -- poll the keypad (POKEY) and triggers (GTIA), then reset
;   2  WAITSECS secs  -- count frames via ANTIC VCOUNT, then reset
; "Exit" jumps through the BIOS reset vector, which re-runs the cartridge and so
; re-displays the picture (a cartridge console has no OS to return to).

#if WAITMODE == 0
awloop:
        jmp awloop
#endif

#if WAITMODE == 1
        lda #$03
        sta $e80f               ; POKEY SKCTL -- enable keypad scanning
awloop:
        lda $c010               ; GTIA TRIG0 (fire button); 0 = pressed
        and #$01
        beq awexit
        lda $e80f               ; POKEY SKSTAT; bit2 = 0 while a keypad key is down
        and #$04
        bne awloop
awexit:
        jmp ($fffc)             ; BIOS reset -> re-display
#endif

#if WAITMODE == 2
        lda #<(WAITSECS*RATE)
        sta $80
        lda #>(WAITSECS*RATE)
        sta $81
awloop:
        lda $80
        ora $81
        beq awexit              ; counted all the frames
vw1:
        lda $d40b               ; ANTIC VCOUNT
        bne vw1                 ; wait for top of frame (VCOUNT = 0)
vw2:
        lda $d40b
        beq vw2                 ; wait until it leaves the top -> one frame elapsed
        lda $80
        sec
        sbc #$01
        sta $80
        lda $81
        sbc #$00
        sta $81
        jmp awloop
awexit:
        jmp ($fffc)             ; BIOS reset -> re-display
#endif