redbus: implementation of external bus functions

include/redbus.h

@@ -2,11 +2,11 @@
 
 void rb_enable(void);
 void rb_disable(void);
-
+void rb_disable_ext(void);
 void __fastcall__ rb_set_window(void* address);
-
+void __fastcall__ rb_set_window_ext(void* address);
 void __fastcall__ rb_map_device(unsigned char id);
-
+void rb_enable_ext(void);
 
 
 // 0x00 Map device in Reg A to redbus window.
@@ -31,3 +31,4 @@ void __fastcall__ rb_map_device(unsigned char id);
 // 0x86 Get POR address to A
 
 // 0xFF Output A register to MC logfile.
+

lib/rpc8e/redbus.s

@@ -1,6 +1,6 @@
 .include "mmu.inc"
 
-.export _rb_enable, _rb_disable, _rb_map_device, _rb_set_window
+.export _rb_enable, _rb_disable, _rb_map_device, _rb_set_window, _rb_set_window_ext, _rb_disable_ext
 
 
 .segment "CODE"
@@ -53,3 +53,42 @@ _rb_map_device:
 	rts
 
 
+;------------------------------------------
+; void __fastcall__ rb_set_window_ext(void* address);
+;------------------------------------------
+_rb_set_window_ext:
+	;switch to native 16bit
+	    clc
+        .byte $FB 			; XCE
+	    .byte $C2, $30      ; REP #$30         
+
+	; init redstone external window:
+		;.byte $A9, $00, $03 ; LDA #$0300
+		.byte $EB ; XBA
+		stx $55
+		ora $55
+		.byte $EB ; XBA
+	    mmu $03
+
+	;switch to emulated 8bit
+		.byte $E2, $30      ; SEP #$30
+		sec
+		.byte $FB	    ;XCE
+	rts
+
+	
+;------------------------------------------
+; void __inline__ rb_enable_ext(void);
+;------------------------------------------
+_rb_enable_ext:
+		mmu $04
+	rts
+
+	
+;------------------------------------------
+; void __inline__ rb_enable_ext(void);
+;------------------------------------------
+_rb_disable_ext:
+		mmu $84
+	rts
+