; FLASH GORDON driver
; Copyright 2012, Adrien Destugues <pulkomandy@gmail.com>
; This program is distributed under the terms of the MIT licence

; Start here.
	DI

; Move the screen to $8000 or $0000 so we can display things to the user, while
; C000 will write to the ROM and 4000 will hold the data to write... That could
; get a bit messy so maybe we will need to use the screen at 4000 as a buffer
; for the ROM data as well. Or just use a bank for that ?

; Map the ROM in
; TODO

; ask the user to enable writing
; TODO

; Check if we can read the ROM type
	LD A, 0x90
	CALL send_command

	LD HL, 0xC000

	LD A,(HL)
	CALL printhex
	INC L
	LD A,(HL)
	CALL printhex

	; We should get 0x8F 87
	; TODO check that before continuing with writing the data
	JR $

	; Now reuse and adapt the code from OUL guys !

; That's all folks !
	RET

; Helper routines -----------------------------------------------------

; Send a command to the ROM. The available commands are :
ERASE		equ	0x80
IDENTIFY	equ	0x90
BYTEPROG	equ 0xA0
RESET		equ	0xF0

; Input: Commend to send in A register
send_command:
	; Select ROM 1
	LD BC,0xDF01
	LD HL,0xD555
	LD DE,0xEAAA

	; Select ROM 1 and write 0xAA to address 0xD555
	OUT (C),C
	LD (HL),E

	; Select ROM 2 and write 0x55 to address 0xEAAA
	INC C
	OUT (C),C
	EX DE,HL
	LD (HL), E

	; Select ROM 1 again and write the command to address 0xEAAA
	DEC C
	OUT (C),C
	EX DE,HL
	LD (HL), A

	RET


; Print value of A, as 2 hex digits
printhex
	PUSH	AF
	RRA	
	RRA	
	RRA	
	RRA		;divise A par 8 
	CALL	PRNHEX1	;affiche le premier morceau
	POP	AF	;r{cup la valeur originale pour la suit
PRNHEX1			;affiche la valeur de A sur 1 chiffre
;affiche A sur 1 chiffre en Hexa
	AND	0xF	;ne prend que les unit{s
	OR	A
	DAA		;convertit en d{cimal  
	ADD	A,0xF0	;ajoute 240
	ADC	A,0x40	;ajoute 64+le carry (si >15)
;on a le code ascii du chiffre @ afficher
	JP	0xBB5A	;call-ret
;