;this is for making BG2 disappear when pressing X+R and having the book of mudora (modified parallel worlds x button secret), i use bank 0x3C for the whole code
;WRITTEN: 	by XaserLE
;THANKS TO: -MathOnNapkins' Zelda Doc's
;			-wiiqwertyuiop for his Zelda Disassembly

; Layer Flags: xxxsabcd (i count BG from 1 to 4 - MathOnNapkins RAM-Map counts from 0 to 3)
; s - Sprite layer enabled 
; a - BG4 enabled
; b - BG3 enabled
; c - BG2 enabled
; d - (BG1 disabled) --> only works properly if the room uses the feature "BG2 on Top"

header
lorom


ORG $0288FD			; go to the code that branches behind the dungeon map load if player didn't press X
BRA $1C				; make it always branch, so map isn't loaded anymore

ORG $068365			; go to an originally JSL that is executed every frame
JSL $3CA600			; overwrite it (originally JSL $099F91)

ORG $3CA600			; go to expanded space to write our routine (keep EveryFrame.asm in mind for the right adresses)
LDA $1B				; load data that tells us whether we are in a building or not
AND #$01			; are we in a building?
BEQ END_XBUTTONSECRET				; if not, don't use the x-button-secret
	;BG2 disable on pressing R
	LDA $7EF34D			; load book of mudora slot
	CMP #$01			; do we have the moon pearl?
	BNE $0F				; if not, go to enable BG2
	LDA $F2				; load unfiltered joypad 1 register (AXLR|????)
	AND #$50 			; delete all bits except those for X and R
	SEC 				; set carry for the following subtraction
	SBC #$50			; X+R button pressed? (if yes, zero flag is set)
	BNE $06				; if not, go to enable BG2
		LDA $1C				; load layer flags
		AND #$FD			; disable BG2 (0xFD = 11111101)
		BRA $04				; go to store layer flags
	LDA $1C				; load layer flags
	ORA #$02			; enable BG2 (0x02 = 00000010)
	STA $1C				; store layer flags
END_XBUTTONSECRET:
JSL $099F91			; at least execute original code
RTL