millfork/examples/c64/rasterirq.mfk

void RasterA() {
    vic_rasterirq_acknowledge()

    // First raster split, set border to black
    vic_border = black

    // Set up next raster split
    vic_rasterirq_reconfigure(RasterB.addr, $40)

    vic_rasterirq_return()
}

void RasterB() {
    vic_rasterirq_acknowledge()

    // Second raster split, Dark grey
    vic_border = dark_grey

    // Set up next raster split
    vic_rasterirq_reconfigure(RasterC.addr, $A0)

    vic_rasterirq_return()
}

void RasterC() {
    vic_rasterirq_acknowledge()

    // Third raster split, Light grey
    vic_border = light_grey

    // Set up next raster split
    vic_rasterirq_reconfigure(RasterA.addr, $00)

    vic_rasterirq_return()
}

void main() {
    byte i

    // Configure Raster IRQ
    vic_rasterirq_configure(RasterA.addr, $00)

    // Loop forever
    while true {
        i = 0   // Do nothing here
    }
}