added joystick support to MEGA65 keyboard scanner

src/kernal/board_m65/mega65_imports_C.s

@@ -13,4 +13,5 @@
 
 ;; #ALIAS# kb_matrix_alwaysrepeat          = KERNAL_0.kb_matrix_alwaysrepeat
 ;; #ALIAS# __kb_matrix_alwaysrepeat_end    = KERNAL_0.__kb_matrix_alwaysrepeat_end
-
+;; #ALIAS# kb_matrix_joy_status            = KERNAL_0.kb_matrix_joy_status
+;; #ALIAS# kb_matrix_joy_keytab_idx        = KERNAL_0.kb_matrix_joy_status

src/kernal/keyboard/scnkey.s

@@ -259,7 +259,7 @@ scnkey_joystick_1:
 
 scnkey_joystick_filtered:
 
-	; Set appropriate keyboard matrix and key code for joystick event
+	; Decode joystick event using appropriate matrix
 
 	ldy #$03
 @5:

src/kernal/keyboard_m65/mega65_kb_matrix_joy.s

@@ -0,0 +1,37 @@
+;; #LAYOUT# M65 KERNAL_C #TAKE
+;; #LAYOUT# *   *        #IGNORE
+
+;
+; Matrix for retrieving C64 joystick status and inject is as keyboard event
+;
+
+!ifndef CONFIG_JOY1_OR_JOY2_CURSOR {
+
+kb_matrix_joy_status:
+
+	!byte %00001110                ; up
+	!byte %00001101                ; down
+	!byte %00001011                ; left
+	!byte %00000111                ; right
+
+kb_matrix_joy_keytab_idx:
+
+	!byte $07                      ; up
+	!byte $07                      ; down
+	!byte $02                      ; left
+	!byte $02                      ; right
+}
+
+kb_matrix_joy_keytab_lo:
+
+	!byte <__kb_matrix_shift       ; up
+	!byte <__kb_matrix_normal      ; down
+	!byte <__kb_matrix_shift       ; left
+	!byte <__kb_matrix_normal      ; right
+
+kb_matrix_joy_keytab_hi:
+
+	!byte >__kb_matrix_shift       ; up
+	!byte >__kb_matrix_normal      ; down
+	!byte >__kb_matrix_shift       ; left
+	!byte >__kb_matrix_normal      ; right

src/kernal/keyboard_m65/mega65_scnkey.s

@@ -192,18 +192,46 @@ m65_scnkey_try_joystick:
 
 m65_scnkey_try_joy1:
 
-	+nop
-	; XXX provide implementation
+	lda #$FF
+	sta CIA1_PRA                       ; disconnect all the rows to prevent keyboard interference
+
+	lda CIA1_PRB
+	bra m65_scnkey_try_joy_common
 
 m65_scnkey_try_joy2:
 
-	+nop
-	; XXX provide implementation
+	lda CIA1_PRA
+
+	; FALLTROUGH
 
 m65_scnkey_try_joy_common:
 
-	; XXX provide implementation
+	and #%00001111                     ; filter out anything but joystick movement
+	beq m65_scnkey_no_keys             ; branch if no joystick movement detected
+
+	; Decode joystick event using appropriate matrix
+
+	ldy #$03
+@1:
+	cmp kb_matrix_joy_status, y
+	beq @2
+	dey
+	bpl @1
+
+	; Not found
+
 	bra m65_scnkey_no_keys
+@2:
+	; Found joystick movement
+
+	lda kb_matrix_joy_keytab_lo, y
+	sta KEYTAB+0
+	lda kb_matrix_joy_keytab_hi, y
+	sta KEYTAB+1
+	lda kb_matrix_joy_keytab_idx, y
+	tay
+
+	; FALLTROUGH
 
 m65_scnkey_got_key: ; .Y should now contain the key offset in matrix pointed by KEYTAB