From 415c599310d8e1bb9c0a8bd2b6b48c92bb68be40 Mon Sep 17 00:00:00 2001
From: Irmen de Jong <irmen@razorvine.net>
Date: Sun, 14 May 2023 23:33:57 +0200
Subject: [PATCH] update cx16 keyhandler example to r43 keyboard changes

---
 examples/cx16/keyboardhandler.p8 | 46 +++++++++-----------------------
 1 file changed, 12 insertions(+), 34 deletions(-)

diff --git a/examples/cx16/keyboardhandler.p8 b/examples/cx16/keyboardhandler.p8
index 8c9b18798..ede7f157c 100644
--- a/examples/cx16/keyboardhandler.p8
+++ b/examples/cx16/keyboardhandler.p8
@@ -9,17 +9,16 @@ 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
         sys.clear_irqd()
 
-        bool escape_pressed
-        while not escape_pressed {
-            handle_keyboard_event()
+        while handle_keyboard_event() {
         }
+
         sys.set_irqd()
         cx16.KEYHDL = old_keyhdl
         sys.clear_irqd()
@@ -30,70 +29,49 @@ main {
     ; 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() {
+    sub handle_keyboard_event() -> bool {
         ; 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
+            return true
         keyhdl_event = false
-        txt.print_ubhex(keyhdl_prefix, true)
-        txt.chrout(':')
         txt.print_ubhex(keyhdl_scancode, true)
         txt.spc()
-        if keyhdl_updown
+        if keyhdl_scancode & $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
-        }
+        return keyhdl_scancode!=$6e         ; escape breaks the loop
     }
 
     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).
+        ; because the X register gets overwritten here by the kernal.
+        ; Pog8 uses the X register internally (for the software eval 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
+        ; Unfortunately this also means you cannot decide easily 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
+
+            lda #0     ; By setting A=0 we will eat this key event. leave A unchanged to pass it through.
             rts
         }}
     }