From 67b2f3fc7d655216099a6035f5b7a6e17f1e753b Mon Sep 17 00:00:00 2001
From: Paul Gardner-Stephen <paul@servalproject.org>
Date: Sat, 20 Apr 2019 00:59:09 +0930
Subject: [PATCH] refactor keyboard scanner somewhat, and have no variables in
 ROM(!)

---
 c64/kernal/irq_handler.s   |  9 +++++++++
 c64/kernal/scan_keyboard.s | 26 +++++++++++++-------------
 2 files changed, 22 insertions(+), 13 deletions(-)

diff --git a/c64/kernal/irq_handler.s b/c64/kernal/irq_handler.s
index 8d8294c5..1db6d0db 100644
--- a/c64/kernal/irq_handler.s
+++ b/c64/kernal/irq_handler.s
@@ -27,5 +27,14 @@ default_irq_handler:
 
 	jsr blink_cursor
 	jsr scan_keyboard
+
+	lda KeyQuantity
+	sta $0400
+	lda Buffer+0
+	sta $0401
+	lda Buffer+1
+	sta $0402
+	lda Buffer+2
+	sta $0403
 	
 	jmp return_from_interrupt
diff --git a/c64/kernal/scan_keyboard.s b/c64/kernal/scan_keyboard.s
index 035096d4..4b81e6ee 100644
--- a/c64/kernal/scan_keyboard.s
+++ b/c64/kernal/scan_keyboard.s
@@ -156,6 +156,15 @@
     .alias TempZP            $B6  ;// 1 byte
     .alias SimultaneousKeys  $F7  ;// 1 byte
 
+	;; Reuse RS232 variables, since they should not be used
+	;; by other things
+	;; These are initialised in cinit all to $FF
+    .alias BufferOld         $293 ; 3 bytes
+	.alias Buffer 	$297 	; 4 bytes
+	.alias BufferQuantity $29B ; 1 byte
+
+
+	
     ;// Operational Variables
     .alias MaxKeyRollover 3
 
@@ -180,7 +189,8 @@ KeyInRow:
 	asl
 	bcs nokey0
 	jsr KeyFound
-nokey0:	
+nokey0:
+	inx
         asl
         bcs nokey1
         jsr KeyFound
@@ -233,11 +243,10 @@ KeyFound:
 	;; was: ldy KeyTable,x
 	pha
 	txa
-	tay
-	pla
 	
 	ldx KeyQuantity
-	sty BufferNew,x
+	sta BufferNew,x
+	pla
 	ldx TempZP
 	rts
 
@@ -536,12 +545,3 @@ TooManyNewKeys:
     sec
     rts
 
-BufferOld:
-    .byte $ff, $ff, $ff
-
-Buffer:
-    .byte $ff, $ff, $ff, $ff
-
-BufferQuantity:
-    .byte $ff
-