prog8/examples/cx16/multi-irq-old.p8

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%import palette
%import textio
%import syslib
%zeropage basicsafe
; Example that shows a way to handle multiple IRQ sources on the X16.
; This uses the "OLD" way using the interrupt handler routines in sys.
; (see multi-irq-new example to do it the "new" way)
; Currently only Vera interrupts are supported. VIA irqs are an exercise for the reader.
main {
sub start() {
sys.set_rasterline(150)
sys.set_irq(&irq.master_handler) ; ..will just enable vsync..
cx16.VERA_IEN |= 2 ; .. so also enable line irq here.
txt.print("\n\n\nx16 irq handlers installed (old style)\n")
txt.print("red = vsync irq\n")
txt.print("green = first line irq\n")
txt.print("blue = second line irq\n")
}
}
irq {
sub master_handler() -> bool {
ubyte irqsrc = cx16.VERA_ISR & cx16.VERA_IEN ; only consider sources that are enabled
ror(irqsrc)
if_cs {
vsync_irq()
return true ; run system IRQ handler. It will ack the vsync IRQ as well.
}
ror(irqsrc)
if_cs {
line_irq()
cx16.VERA_ISR |= 2 ; ack the irq
return false
}
ror(irqsrc)
if_cs {
sprcol_irq()
cx16.VERA_ISR |= 4 ; ack the irq
return false
}
ror(irqsrc)
if_cs {
aflow_irq()
; note: AFLOW can only be cleared by filling the audio FIFO for at least 1/4. Not via the ISR bit.
return false
}
; weird irq
return false
}
sub vsync_irq() {
cx16.save_vera_context()
palette.set_color(0, $f00)
repeat 1000 {
cx16.r0++
}
palette.set_color(0, $000)
cx16.restore_vera_context()
}
sub line_irq() {
cx16.save_vera_context()
if cx16.VERA_SCANLINE_L==150 {
palette.set_color(0, $0f0)
sys.set_rasterline(200) ; prepare next line irq
} else {
palette.set_color(0, $00f)
sys.set_rasterline(150) ; back to first line irq
}
repeat 500 {
cx16.r0++
}
palette.set_color(0, $000)
cx16.restore_vera_context()
}
sub sprcol_irq() {
; nothing here yet
}
sub aflow_irq() {
; nothing here yet
}
}