added support for the Commander X16 memory layout

c64/kernal/iostack/pop_keyboard_buffer.s

@@ -0,0 +1,25 @@
+// #LAYOUT# STD *        #TAKE
+// #LAYOUT# *   KERNAL_0 #TAKE
+// #LAYOUT# *   *        #IGNORE
+
+// Pop key out of keyboard buffer
+// Disable interrupts while reading from keyboard buffer
+// so that no race conditions can occur
+//
+// CPU registers that has to be preserved: .X
+//
+
+pop_keyboard_buffer:
+
+	ldy #$01
+
+	sei
+!:	lda KEYD,y
+	sta KEYD-1,y
+	iny
+	cpy XMAX
+	bne !-
+	dec NDX
+	cli
+
+	rts