IRQ: {
    Setup: {
        sei

        //disable CIA Interrupts
        lda #$7f
        sta $dc0d
        sta $dd0d

        lda $dc0d                                          // read interupts to clear them
        lda $dd0d

        // enable vbl interrupt
//      lda VIC.INTERRUPT_CONTROL
//      ora #%00000001
//      sta VIC.INTERRUPT_CONTROL

        lda #1
        sta $d01a

        //routine called when interrupt triggers
        lda #<TitlesIRQHandler
        ldx #>TitlesIRQHandler
        sta $fffe //0314
        stx $ffff //0315

        lda #$00
        sta VIC.RASTER_Y
//      lda VIC.SCREEN_CONTROL_1
//      and #%01111111
//      sta VIC.SCREEN_CONTROL_1

        asl VIC.INTERRUPT_STATUS
        cli

        rts
    }

    SwitchToGame: {
        sei
        //routine called when interrupt triggers
        lda #<MainIRQ
        ldx #>MainIRQ
        sta $fffe //0314
        stx $ffff //0315

        cli
        rts
    }

    TitlesIRQHandler: {

        :StoreState()

            lda #$00
            sta $d012
            /*
    ; Basics : IRQ
; @L       Wait for Y-Pos
;          write (new) Y-Position
;          write (new) Sprite-Pointer
;          set some other registers according to the sprite
;          wait 21+1 (Spriteheight+1) Rasterlines
;          JMP @L
            */
            lda $d012
            cmp #100
            bne !skip+
                inc $d020
                lda #TitleScreen.FrameA
                clc
                adc TitleScreen.GameMode
                sta TitleScreen.sprite_pointers + 2

            !skip:

            jsr music_play
            lsr VIC.INTERRUPT_STATUS     // ********************
        :RestoreState()

        rti
    }

    MainIRQ: {

        :StoreState()
            inc Game.GameCounter
            dec Game.GameTimerTick
            dec Game.PushButtonTimer + 1
            dec Game.FallGuyTimer + 1
            dec Game.CementSpillTimer + 1
            dec Game.ScoreBlinkingTimer + 1
            dec Game.CratePourTimer1 + 1
            dec Game.CratePourTimer2 + 1
            //inc $d020
            //dec $d021
            lda #$01
            sta Game.PerformFrameCodeFlag

            jsr music_play
            lsr VIC.INTERRUPT_STATUS      // **********************8
        :RestoreState()

        rti
    }
}

.macro StoreState() {
    pha //A
    txa
    pha //X
    tya
    pha //Y
}

.macro RestoreState() {
    pla
    tay
    pla
    tax
    pla
}