X-Git-Url: http://git.joshuawise.com/fpgaboy.git/blobdiff_plain/f6fa1d6e1393de5d18302b8674ed1616afdfcefb..80ecd2fe23cfab4f410f8f760dea4b44d72a82c9:/diag.asm

diff --git a/diag.asm b/diag.asm
index 8e09874..50cefe7 100644
--- a/diag.asm
+++ b/diag.asm
@@ -32,6 +32,8 @@ main:
 	
 	ld hl, signon
 	call puts
+
+	call putscreen
 	
 	ei
 
@@ -48,6 +50,80 @@ main:
 signon:
 	db $0D,$0A,$1B,"[1mFPGABoy Diagnostic ROM",$1B,"[0m",$0D,$0A,0
 
+putscreen:
+	; Wait for vblank
+	call .vblwait
+
+	ld hl, $8000	; Copy two tiles.
+	ld a, $AA
+	ld [hli], a
+	ld [hli], a
+	ld a, $55
+	ld [hli], a
+	ld [hli], a
+	ld a, $AA
+	ld [hli], a
+	ld [hli], a
+	ld a, $55
+	ld [hli], a
+	ld [hli], a
+	ld a, $AA
+	ld [hli], a
+	ld [hli], a
+	ld a, $55
+	ld [hli], a
+	ld [hli], a
+	ld a, $AA
+	ld [hli], a
+	ld [hli], a
+	ld a, $55
+	ld [hli], a
+	ld [hli], a
+	xor a
+	ld [hli], a
+	ld [hli], a
+	ld [hli], a
+	ld [hli], a
+	ld [hli], a
+	ld [hli], a
+	ld [hli], a
+	ld [hli], a
+	ld [hli], a
+	ld [hli], a
+	ld [hli], a
+	ld [hli], a
+	ld [hli], a
+	ld [hli], a
+	ld [hli], a
+	ld [hli], a
+	
+	ld hl, $9800
+.vloop:	call .vblwait
+	ld c, $40
+.loop:	ld a, $01
+	ld [hli], a
+	xor a
+	ld [hli], a
+	ld a, h
+	cp $9C
+	ret z
+	dec c
+	xor a
+	cp c
+	jr nz,.loop
+	jr .vloop
+
+.vblwait:
+.stat1:	ld a, [$FF41]	; STAT
+	and $03
+	cp $00
+	jp nz, .stat1
+.stat2:	ld a, [$FF41]
+	and $03
+	cp $01
+	jr nz, .stat2
+	ret
+
 vbl:
 	PUSH AF
 	PUSH BC
@@ -57,11 +133,34 @@ vbl:
 	xor a
 	ld [$FF0F], a
 
-	ld c, $42	; SCY
-	ld a, [c]
-	inc a
-	ld [c], a
+	ld a, [$FF51]
+	ld b, a
+	and $80
+	cp $80
+	jr nz, .nothing
+	ld c, $0
 
+	ld a, b
+	and $1
+	cp c
+	call nz, .scyup
+	
+	ld a, b
+	and $2
+	cp c
+	call nz, .scydown
+	
+	ld a, b
+	and $4
+	cp c
+	call nz, .scxup
+	
+	ld a, b
+	and $8
+	cp c
+	call nz, .scxdown
+
+.nothing:
 	POP HL
 	POP DE
 	POP BC
@@ -69,6 +168,23 @@ vbl:
 
 	RETI
 
+.scyup:	ld hl, $FF42
+	inc [hl]
+	ret
+
+.scydown:	ld hl, $FF42
+	dec [hl]
+	ret
+
+.scxup:	ld hl, $FF43
+	inc [hl]
+	ret
+
+.scxdown:	ld hl, $FF43
+	dec [hl]
+	ret	
+	
+
 lcdc:
 	PUSH AF
 	PUSH BC