; Read back char registers

; Version 1.0

; $Id: charread.a48 390 2003-07-19 12:41:28Z sgust $

; History:
; Version 1.0
;   first release

; This program shows that the char registers have a different meaning when
; read back in gfxon (junk) than in gfxoff.

; Copyright (C) 2003 by Soeren Gust, sgust@ithh.informationstheater.de

; Permission is hereby granted, free of charge, to any person obtaining a copy
; of this software and associated documentation files (the "Software"), to deal
; in the Software without restriction, including without limitation the rights
; to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
; copies of the Software, and to permit persons to whom the Software is
; furnished to do so, subject to the following conditions:

; The above copyright notice and this permission notice shall be included in
; all copies or substantial portions of the Software.

; THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
; IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
; FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL THE
; AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
; LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
; OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
; THE SOFTWARE.

; You can always get the latest version at http://soeren.informationstheater.de

; This is ugly, badly commented, unsupported code!

	cpu	8048

	org	400h
	
	include	"g7000.h"
	include	"bitfuncs.inc"	; part of asl distribution

iram_data	equ	020h

	jmp	selectgame	; RESET
	jmp	irq		; interrupt
	jmp	timer		; timer
	jmp	vsyncirq	; VSYNC-interrupt
	jmp	main		; after selectgame
	jmp	soundirq	; sound-interrupt

timer	retr			; we don't need timer

main
	; print char
	call	gfxoff
	mov	r0,#vdc_char0
	mov	r3,#010h
	mov	r4,#010h
	mov	r5,#02fh
	mov	r6,#col_chr_white
	call	printchar
	call	gfxon
	call	waitvsync
	call	waitvsync

	; read back data with gfx on
	mov	r0,#vdc_char0
	mov	r1,#iram_data
	mov	r2,#4
.lop0	movx	a,@r0
	mov	@r1,a
	inc	r0
	inc	r1
	djnz	r2,.lop0

	call	gfxoff
	call	waitvsync

	; read back data with gfx off
	mov	r0,#vdc_char0
	mov	r2,#4
.lop1	movx	a,@r0
	mov	@r1,a
	inc	r0
	inc	r1
	djnz	r2,.lop1

	; print data, high nibble on
	mov	r0,#vdc_quad0
	mov	r1,#iram_data
	mov	r2,#4
	mov	r3,#010h
	mov	r4,#028h
.lop2	mov	a,@r1
	swap	a
	call	printnibble
	inc	r1
	djnz	r2,.lop2

	; print data, low nibble on
	mov	r0,#vdc_quad1
	mov	r1,#iram_data
	mov	r2,#4
	mov	r3,#018h
.lop3	mov	a,@r1
	call	printnibble
	inc	r1
	djnz	r2,.lop3

	; print data, high nibble off
	mov	r0,#vdc_quad2
	mov	r1,#iram_data+4
	mov	r2,#4
	mov	r3,#010h
	mov	r4,#040h
.lop4	mov	a,@r1
	swap	a
	call	printnibble
	inc	r1
	djnz	r2,.lop4

	; print data, low nibble off
	call	gfxoff
	mov	r0,#vdc_quad3
	mov	r1,#iram_data+4
	mov	r2,#4
	mov	r3,#018h
.lop5	mov	a,@r1
	call	printnibble
	inc	r1
	djnz	r2,.lop5
	call	gfxon

stop	jmp	stop

printnibble
	anl	a,#0fh
	add	a,#lo(hextable)
	movp	a,@a
	mov	r5,a
	call	printchar
	ret

hextable
	db	0,1,2,3,4,5,6,7,8,9,020h,025h,023h,01ah,012h,01bh

	end