mirror of
https://github.com/irmen/prog8.git
synced 2024-09-07 19:54:26 +00:00
95 lines
3.2 KiB
Lua
95 lines
3.2 KiB
Lua
%import textio
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%zeropage basicsafe
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%option no_sysinit
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main {
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sub start() {
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txt.print("ps2 custom key handler test - press keys! esc to quit!\n")
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sys.set_irqd()
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uword old_keyhdl = cx16.KEYHDL
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cx16.KEYHDL = &keyboard_scancode_handler
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sys.clear_irqd()
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bool escape_pressed
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while not escape_pressed {
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handle_keyboard_event()
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}
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sys.set_irqd()
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cx16.KEYHDL = old_keyhdl
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sys.clear_irqd()
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}
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; Keyboard handler communication variables.
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; these need to be in block scope instead of in a subroutine,
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; so that they won't get overwritten with initialization values every time.
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; The assembly keyboard handler will set these, prog8 will read them.
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bool @shared keyhdl_event ; is there a keyboard event to handle?
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ubyte @shared keyhdl_prefix
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ubyte @shared keyhdl_scancode
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ubyte @shared keyhdl_updown
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sub handle_keyboard_event() {
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; Potentially handle keyboard event.
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; Note that we do this from the program's main loop instead of
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; the actual keyboard handler routine itself.
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; The reason for this is documented below in the handler assembly routine.
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if not keyhdl_event
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return
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keyhdl_event = false
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txt.print_ubhex(keyhdl_prefix, true)
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txt.chrout(':')
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txt.print_ubhex(keyhdl_scancode, true)
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txt.spc()
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if keyhdl_updown
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txt.chrout('u')
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else
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txt.chrout('d')
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txt.nl()
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if keyhdl_prefix==0 and keyhdl_scancode==119 and keyhdl_updown {
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; escape was pressed! exit back to basic
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main.start.escape_pressed = true
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}
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}
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asmsub keyboard_scancode_handler() {
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; NOTE that the keyboard handler is an asm subroutine.
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; Unfortunately is it not possible to use prog8 code or calls here,
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; because the X register gets overwritten here (to store the prefix byte)
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; and prog8 uses the X register internally (for the evaluation stack).
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; So it is unsafe to call prog8 code from here because the evaluation stack pointer
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; will be invalid which produces undefined results.
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; So, instead, we store the various keyboard event bytes and signal
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; the main prog8 program that a keyboard event has occurred.
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; It then processes it independently from the assembly code here.
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;
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; Unfortunately this also means you cannot decide from that prog8 code
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; if the keyboard press should be consumed/ignored or put into the keyboard queue
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; (this is controlled by returning 0 or 1 in register A here)
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%asm {{
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php
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pha
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phx
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stz keyhdl_updown
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bcc +
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inc keyhdl_updown
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+ stx keyhdl_prefix
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sta keyhdl_scancode
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lda #1
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sta keyhdl_event
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; we can do additional stuff here and decide if we want to
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; consume the key event or not (A=0 or A!=0)
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plx
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pla
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lda #0 ;By setting A=0 we will remove this key event for now
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tax
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plp
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rts
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}}
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}
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}
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