Started on Gameboy support.

2 files changed, 96 insertions, 1 deletions

diff --git a/src/example/Makefile b/src/example/Makefile
index 7c53209..d184de0 100644
--- a/src/example/Makefile
+++ b/src/example/Makefile
@@ -20,7 +20,7 @@
 # Makefile for examples
 #
 
-ALL	= spectrum.tap c64.t64 zx81.p
+ALL	= spectrum.tap c64.t64 zx81.p gb.rom
 CASM	= ../casm
 
 all: $(ALL) $(CASM)
@@ -39,5 +39,8 @@ c64.t64: c64.asm $(CASM)
 zx81.p: zx81.asm $(CASM)
 	$(CASM) zx81.asm
 
+gb.rom: gb.asm $(CASM)
+	$(CASM) gb.asm
+
 clean:
 	rm -f $(ALL)
diff --git a/src/example/gb.asm b/src/example/gb.asm
new file mode 100644
index 0000000..15cc50b
--- /dev/null
+++ b/src/example/gb.asm
@@ -0,0 +1,92 @@
+	
+	cpu	gameboy
+	option	+list
+	option	list-labels,all
+
+	option	output-file,gb.rom
+	option	output-format,gameboy
+
+	option	gameboy-irq,vbl,vbl_code
+
+VRAM	equ	$8000
+SCRN	equ	$9800
+OAM	equ	$fe00
+LCDC	equ	$ff40
+STAT	equ	$ff41
+
+READY	equ	$ff81
+XPOS	equ	$ff82
+
+VBLANK	macro
+	push	af
+.wait
+	ldh	a,(LCDC)
+	cp	$91
+	jr	nz,wait
+
+	pop	af
+
+	endm
+
+
+	;
+	; **********
+	; CODE START
+	; **********
+	;
+	org	$150
+
+	di
+	xor	a
+	ldh	(READY),a
+	ld	sp,$fffe
+
+	; Set LCD so only sprites show
+	;
+	ld	a,$82
+	ldh	(LCDC),a
+	ld	a,$10
+	ldh	(STAT),a
+
+	; Copy to VRAM
+	;
+	ld	hl,VRAM
+	ld	de,sprite
+	ld	a,16
+
+	VBLANK
+
+.copy
+	ld	a,(hl+)
+	ld	(de),a
+	inc	de
+	dec	a
+	jr	nz,copy
+
+	ld	a,1
+	ldh	(READY),a
+
+.idle
+	halt
+	nop
+	jr	idle
+
+vbl_code:
+	ldh	a,(READY)
+	jr	z,finish
+
+	ldh	a,(XPOS)
+	inc	a
+	ldh	(XPOS),a
+	ld	(OAM+1),a
+	xor	a
+	ld	(OAM),a
+	ld	(OAM+2),a
+	ld	(OAM+3),a
+
+.finish
+	reti
+
+sprite:
+	defs	16,$ff
+