update cx16 keyhandler example to r43 keyboard changes

examples/cx16/keyboardhandler.p8

@@ -2,99 +2,57 @@
 %zeropage basicsafe
 %option no_sysinit
 
-; The documentation for custom PS2 key handlers can be found here:
+; The documentation for a custom key handler can be found here:
 ; https://github.com/X16Community/x16-docs/blob/master/X16%20Reference%20-%2002%20-%20Editor.md#custom-keyboard-scancode-handler
 
 main {
 
     sub start() {
 
-        txt.print("ps2 custom key handler test - press keys! esc to quit!\n")
+        txt.print("custom key handler test - press keys! esc to quit!\n")
 
         sys.set_irqd()
         uword old_keyhdl = cx16.KEYHDL
-        cx16.KEYHDL = &keyboard_scancode_handler
+        cx16.KEYHDL = &main.key_handler.asm_hook
         sys.clear_irqd()
 
         bool escape_pressed
         while not escape_pressed {
-            handle_keyboard_event()
+            ; do nothing here, just wait until ESC is pressed
         }
+
         sys.set_irqd()
         cx16.KEYHDL = old_keyhdl
         sys.clear_irqd()
     }
 
-    ; Keyboard handler communication variables.
-    ; these need to be in block scope instead of in a subroutine,
-    ; so that they won't get overwritten with initialization values every time.
-    ; The assembly keyboard handler will set these, prog8 will read them.
-    bool @shared keyhdl_event       ; is there a keyboard event to handle?
-    ubyte @shared keyhdl_prefix
-    ubyte @shared keyhdl_scancode
-    ubyte @shared keyhdl_updown
-
-    sub handle_keyboard_event() {
-        ; Potentially handle keyboard event.
-        ; Note that we do this from the program's main loop instead of
-        ; the actual keyboard handler routine itself.
-        ; The reason for this is documented below in the handler assembly routine.
-        if not keyhdl_event
-            return
-        keyhdl_event = false
-        txt.print_ubhex(keyhdl_prefix, true)
-        txt.chrout(':')
-        txt.print_ubhex(keyhdl_scancode, true)
+    sub key_handler(ubyte keycode) -> bool {
+        txt.print_ubhex(keycode, true)
         txt.spc()
-        if keyhdl_updown
+        if keycode & $80
             txt.chrout('u')
         else
             txt.chrout('d')
         txt.nl()
-        if keyhdl_prefix==0 and keyhdl_scancode==119 and keyhdl_updown {
-            ; escape was pressed! exit back to basic
-            main.start.escape_pressed = true
+        if keycode==$6e {
+            main.start.escape_pressed=true
+        }
+        return false        ; this eats the keypress - return true if you want to pass it through
+
+        asmsub asm_hook(ubyte keycode @A) -> ubyte @A {
+            %asm {{
+                sta  key_handler.keycode
+                pha
+                jsr  key_handler
+                tay
+                pla
+                cpy  #0
+                beq  +
+                rts
++               tya
+                rts
+            }}
         }
     }
 
-    asmsub keyboard_scancode_handler() {
-
-        ; NOTE that the keyboard handler is an asm subroutine.
-        ; Unfortunately is it not possible to use prog8 code or calls here,
-        ; because the X register gets overwritten here (to store the prefix byte)
-        ; and prog8 uses the X register internally (for the evaluation stack).
-        ; So it is unsafe to call prog8 code from here because the evaluation stack pointer
-        ; will be invalid which produces undefined results.
-        ; So, instead, we store the various keyboard event bytes and signal
-        ; the main prog8 program that a keyboard event has occurred.
-        ; It then processes it independently from the assembly code here.
-        ;
-        ; Unfortunately this also means you cannot decide from that prog8 code
-        ; if the keyboard press should be consumed/ignored or put into the keyboard queue
-        ; (this is controlled by returning 0 or 1 in register A here)
-        ;
-        ; see:
-        ; https://github.com/X16Community/x16-docs/blob/master/X16%20Reference%20-%2002%20-%20Editor.md#custom-keyboard-scancode-handler
-
-        %asm {{
-            php
-            pha
-            phx
-            stz  keyhdl_updown
-            bcc  +
-            inc  keyhdl_updown
-+           stx  keyhdl_prefix
-            sta  keyhdl_scancode
-            lda  #1
-            sta  keyhdl_event
-            ; we can do additional stuff here and decide if we want to
-            ; consume the key event or not (A=0 or A!=0)
-            plx
-            pla
-            lda #0     ;By setting A=0 we will remove this key event for now
-            tax
-            plp
-            rts
-        }}
-    }
 }