Move VBlank function to a file

main.asm

@@ -58,562 +58,34 @@ SECTION "start",HOME[$150]
 
 INCBIN "baserom.gbc",$150,$283 - $150
 
+
 VBlank: ; 283
-	push af
+INCLUDE "vblank.asm"
-	push bc
-	push de
-	push hl
-	
-; get vblank type
-	ld a, [$ff9e]
-	and $7
-	
-; get fn pointer
-	ld e, a
-	ld d, $0
-	ld hl, .VBlanks
-	add hl, de
-	add hl, de
-	ld a, [hli]
-	ld h, [hl]
-	ld l, a
-	
-; down to business
-	call JpHl
-	
-; since this is called once per frame
-	call GameTimer
-	
-	pop hl
-	pop de
-	pop bc
-	pop af
-	reti
-; 2a1
-
-.VBlanks ; 2a1
-	dw VBlank0 ; 0
-	dw VBlank1 ; 1
-	dw VBlank2 ; 2
-	dw VBlank3 ; 3
-	dw VBlank4 ; 4
-	dw VBlank5 ; 5
-	dw VBlank6 ; 6
-	dw VBlank0 ; 7
-; 2b1
-
-
-VBlank0: ; 2b1
-; normal operation
-
-; rng
-; scx, scy, wy, wx
-; bg map buffer
-; palettes
-; dma transfer
-; bg map
-; tiles
-; oam
-; joypad
-; sound
-
-; inc frame counter
-	ld hl, $ff9b
-	inc [hl]
-	
-; advance rng
-	ld a, [$ff04] ; divider
-	ld b, a
-	ld a, [$ffe1]
-	adc b
-	ld [$ffe1], a
-	
-	ld a, [$ff04] ; divider
-	ld b, a
-	ld a, [$ffe2]
-	sbc b
-	ld [$ffe2], a
-	
-; save bank
-	ld a, [$ff9d] ; current bank
-	ld [$ff8a], a
-	
-; scroll x
-	ld a, [$ffcf]
-	ld [$ff43], a ; scx
-; scroll y
-	ld a, [$ffd0]
-	ld [$ff42], a ; scy
-; window y
-	ld a, [$ffd2]
-	ld [$ff4a], a ; wy
-; window x + 7
-	ld a, [$ffd1]
-	ld [$ff4b], a ; wx
-	
-; some time management is in order
-; only have time for one of these during vblank
-	
-; bg map buffer has priority
-	call UpdateBGMapBuffer
-	jr c, .doneframeaction
-	
-; then pals
-	call UpdatePalsIfCGB
-	jr c, .doneframeaction
-	
-; dma transfer
-	call DMATransfer
-	jr c, .doneframeaction
-	
-; bg map
-	call UpdateBGMap
-	
-; these have their own timing checks
-	call SafeLoadTiles
-	call SafeLoadTiles2
-	call SafeTileAnimation
-	
-.doneframeaction
-; oam update off?
-	ld a, [$ffd8]
-	and a
-	jr nz, .vblankoccurred
-	
-; update oam by dma transfer
-	call $ff80
-;	403f:
-;		ld a, $c4
-;		ld [$ff46], a ; oam dma
-;		ld a, $28
-;	.loop
-;		dec a
-;		jr nz, .loop
-;		ret
-
-
-; vblank-sensitive operations are done
-	
-.vblankoccurred
-; tell other fns vblank happened
-	xor a
-	ld [VBlankOccurred], a
-	
-; dec $cfb1 until 0
-	ld a, [$cfb1]
-	and a
-	jr z, .textdelay
-	dec a
-	ld [$cfb1], a
-	
-.textdelay
-; dec text delay counter until 0
-	ld a, [TextDelayFrames]
-	and a
-	jr z, .joypad
-	dec a
-	ld [TextDelayFrames], a
-	
-.joypad
-	call Joypad
-	
-; update sound
-	ld a, BANK(UpdateSound)
-	rst Bankswitch ; bankswitch
-	call UpdateSound
-	ld a, [$ff8a]
-	rst Bankswitch ; restore bank
-	
-; 
-	ld a, [$ff98]
-	ld [$ffe3], a
-	
-	ret
-; 325
-
-
-VBlank2: ; 325
-; sound only
-
-; save bank
-	ld a, [$ff9d]
-	ld [$ff8a], a
-	
-; update sound
-	ld a, BANK(UpdateSound)
-	rst Bankswitch ; bankswitch
-	call UpdateSound
-	
-; restore bank
-	ld a, [$ff8a]
-	rst Bankswitch
-	
-; tell other fns vblank happened
-	xor a
-	ld [VBlankOccurred], a
-	ret
-; 337
-
-
-VBlank1: ; 337
-; scx, scy
-; palettes
-; bg map
-; tiles
-; oam
-; sound / lcd stat
-
-; save bank
-	ld a, [$ff9d]
-	ld [$ff8a], a
-	
-; scroll x
-	ld a, [$ffcf]
-	ld [$ff43], a ; scx
-	
-; scroll y
-	ld a, [$ffd0]
-	ld [$ff42], a ; scy
-	
-; time-sensitive fns
-	call UpdatePals
-	jr c, .vblankoccurred
-	
-; these have their own timing checks
-	call UpdateBGMap
-	call LoadTiles
-; update oam by dma transfer
-	call $ff80
-;	403f:
-;		ld a, $c4
-;		ld [$ff46], a ; oam dma
-;		ld a, $28
-;	.loop
-;		dec a
-;		jr nz, .loop
-;		ret
-	
-.vblankoccurred
-; tell other fns vblank happened
-	xor a
-	ld [VBlankOccurred], a
-	
-; get requested ints
-	ld a, [$ff0f] ; IF
-	ld b, a
-; discard requested ints
-	xor a
-	ld [$ff0f], a ; IF
-; enable lcd stat
-	ld a, %10 ; lcd stat
-	ld [$ffff], a ; IE
-; rerequest serial int if applicable (still disabled)
-; request lcd stat
-	ld a, b
-	and %1000 ; serial
-	or %10 ; lcd stat
-	ld [$ff0f], a ; IF
-	
-	ei
-; update sound
-	ld a, BANK(UpdateSound)
-	rst Bankswitch ; bankswitch
-	call UpdateSound
-; restore bank
-	ld a, [$ff8a]
-	rst Bankswitch
-	di
-	
-; get requested ints
-	ld a, [$ff0f] ; IF
-	ld b, a
-; discard requested ints
-	xor a
-	ld [$ff0f], a ; IF
-; enable ints besides joypad
-	ld a, %1111 ; serial timer lcdstat vblank
-	ld [$ffff], a ; IE
-; rerequest ints
-	ld a, b
-	ld [$ff0f], a ; IF
-	ret
-; 37f
-
-
-UpdatePals: ; 37f
-; update pals for either dmg or cgb
-
-; check cgb
-	ld a, [$ffe6]
-	and a
-	jp nz, UpdateCGBPals
-	
-; update gb pals
-	ld a, [$cfc7]
-	ld [$ff47], a ; BGP
-	
-	ld a, [$cfc8]
-	ld [$ff48], a ; OBP0
-	
-	ld a, [$cfc9]
-	ld [$ff49], a ; 0BP1
-	
-	and a
-	ret
-; 396
-
-
-VBlank3: ; 396
-; scx, scy
-; palettes
-; bg map
-; tiles
-; oam
-; sound / lcd stat
-
-; save bank
-	ld a, [$ff9d]
-	ld [$ff8a], a
-	
-; scroll x
-	ld a, [$ffcf]
-	ld [$ff43], a ; scx
-; scroll y
-	ld a, [$ffd0]
-	ld [$ff42], a ; scy
-	
-; any pals to update?
-	ld a, [$ffe5]
-	and a
-	call nz, ForceUpdateCGBPals
-	jr c, .vblankoccurred
-; else
-	call UpdateBGMap
-	call LoadTiles
-	
-; update oam by dma transfer
-	call $ff80
-;	403f:
-;		ld a, $c4 ; Sprites / $100
-;		ld [$ff46], a ; oam dma
-;		ld a, $28
-;	.loop
-;		dec a
-;		jr nz, .loop
-;		ret
-	
-.vblankoccurred
-; tell other fns vblank happened
-	xor a
-	ld [VBlankOccurred], a
-	
-; save int flag
-	ld a, [$ff0f] ; IF
-	push af
-; reset ints
-	xor a
-	ld [$ff0f], a ; IF
-; force lcdstat int during sound update
-	ld a, %10 ; lcd stat
-	ld [$ffff], a ; IE
-	ld [$ff0f], a ; IF
-	
-	ei
-; update sound
-	ld a, BANK(UpdateSound)
-	rst Bankswitch ; bankswitch
-	call UpdateSound
-; restore bank
-	ld a, [$ff8a]
-	rst Bankswitch
-	di
-	
-; request lcdstat
-	ld a, [$ff0f] ; IF
-	ld b, a
-; and any other ints
-	pop af
-	or b
-	ld b, a
-; reset ints
-	xor a
-	ld [$ff0f], a ; IF
-; enable ints besides joypad
-	ld a, %1111 ; serial timer lcdstat vblank
-	ld [$ffff], a ; IE
-; request ints
-	ld a, b
-	ld [$ff0f], a ; IF
-	ret
-; 3df
-
-
-VBlank4: ; 3df
-; bg map
-; tiles
-; oam
-; joypad
-; serial
-; sound
-
-; save bank
-	ld a, [$ff9d]
-	ld [$ff8a], a
-	
-	call UpdateBGMap
-	call SafeLoadTiles
-	
-; update oam by dma transfer
-	call $ff80
-;	403f:
-;		ld a, $c4
-;		ld [$ff46], a ; oam dma
-;		ld a, $28
-;	.loop
-;		dec a
-;		jr nz, .loop
-;		ret
-	
-; update joypad
-	call Joypad
-	
-; tell other fns vblank happened
-	xor a
-	ld [VBlankOccurred], a
-	
-; handshake
-	call AskSerial
-	
-; update sound
-	ld a, BANK(UpdateSound)
-	rst Bankswitch ; bankswitch
-	call UpdateSound
-; restore bank
-	ld a, [$ff8a]
-	rst Bankswitch
-	ret
-; 400
-
-
-VBlank5: ; 400
-; scx
-; palettes
-; bg map
-; tiles
-; joypad
-; 
-
-; save bank
-	ld a, [$ff9d]
-	ld [$ff8a], a
-	
-; scroll x
-	ld a, [$ffcf]
-	ld [$ff43], a ; scx
-	
-; if we can update pals, skip this part
-	call UpdatePalsIfCGB
-	jr c, .vblankoccurred
-	
-	call UpdateBGMap
-	call SafeLoadTiles
-	
-.vblankoccurred
-; tell other fns vblank happened
-	xor a
-	ld [VBlankOccurred], a
-	
-; joypad
-	call Joypad
-	
-; discard requested ints
-	xor a
-	ld [$ff0f], a ; IF
-; enable lcd stat
-	ld a, %10 ; lcd stat
-	ld [$ffff], a ; IE
-; request lcd stat
-	ld [$ff0f], a ; IF
-	
-	ei
-; update sound
-	ld a, BANK(UpdateSound)
-	rst Bankswitch ; bankswitch
-	call UpdateSound
-; restore bank
-	ld a, [$ff8a]
-	rst Bankswitch
-	di
-	
-; discard requested ints
-	xor a
-	ld [$ff0f], a ; IF
-; enable ints besides joypad
-	ld a, %1111 ; serial timer lcdstat vblank
-	ld [$ffff], a ; IE
-	ret
-; 436
-
-
-VBlank6: ; 436
-; palettes
-; tiles
-; dma transfer
-; sound
-
-; save bank
-	ld a, [$ff9d]
-	ld [$ff8a], a
-	
-; inc frame counter
-	ld hl, $ff9b
-	inc [hl]
-	
-	call UpdateCGBPals
-	jr c, .vblankoccurred
-	
-	call SafeLoadTiles
-	call SafeLoadTiles2
-	call DMATransfer
-	
-.vblankoccurred
-; tell other fns vblank happened
-	xor a
-	ld [VBlankOccurred], a
-	
-; update sound
-	ld a, BANK(UpdateSound)
-	rst Bankswitch ; bankswitch
-	call UpdateSound
-; restore bank
-	ld a, [$ff8a]
-	rst Bankswitch
-	ret
-; 45a
 
 
 DelayFrame: ; 0x45a
-; delay for one frame
+; Wait for one frame
-	ld a, $1
+	ld a, 1
-	ld [$cfb3], a ; was H_VBLANKOCCURRED
+	ld [VBlankOccurred], a
 
-; wait for the next Vblank, halting to conserve battery
+; Wait for the next VBlank, halting to conserve battery
-.halt\@
+.halt
-	db $76, $00 ; XXX this is a hack--rgbasm adds a nop after this instr even when ints are enabled
+	halt ; rgbasm adds a nop after this instruction by default
-	ld a, [$cfb3]
+	ld a, [VBlankOccurred]
 	and a
-	jr nz, .halt\@ ; 0x465 $f8
+	jr nz, .halt
 	ret
 ; 0x468
 
 DelayFrames: ; 0x468
-; wait n frames, where n is the value in c
+; Wait c frames
 	call DelayFrame
 	dec c
 	jr nz, DelayFrames
 	ret
 ; 0x46f
 
+
 RTC: ; 46f
 ; update time and time-sensitive palettes
 

vblank.asm

@@ -0,0 +1,539 @@
+; VBlank is the interrupt responsible for updating VRAM.
+
+; In Pokemon Crystal, VBlank has been hijacked to act as the
+; main loop. After time-sensitive graphics operations have been
+; performed, joypad input and sound functions are executed.
+
+; This prevents the display and audio output from lagging.
+
+	push af
+	push bc
+	push de
+	push hl
+	
+; get vblank type
+	ld a, [$ff9e]
+	and $7
+	
+; get fn pointer
+	ld e, a
+	ld d, $0
+	ld hl, .VBlanks
+	add hl, de
+	add hl, de
+	ld a, [hli]
+	ld h, [hl]
+	ld l, a
+	
+; down to business
+	call JpHl
+	
+; since this is called once per frame
+	call GameTimer
+	
+	pop hl
+	pop de
+	pop bc
+	pop af
+	reti
+; 2a1
+
+.VBlanks ; 2a1
+	dw VBlank0 ; 0
+	dw VBlank1 ; 1
+	dw VBlank2 ; 2
+	dw VBlank3 ; 3
+	dw VBlank4 ; 4
+	dw VBlank5 ; 5
+	dw VBlank6 ; 6
+	dw VBlank0 ; 7
+; 2b1
+
+
+VBlank0: ; 2b1
+; normal operation
+
+; rng
+; scx, scy, wy, wx
+; bg map buffer
+; palettes
+; dma transfer
+; bg map
+; tiles
+; oam
+; joypad
+; sound
+
+; inc frame counter
+	ld hl, $ff9b
+	inc [hl]
+	
+; advance rng
+	ld a, [$ff04] ; divider
+	ld b, a
+	ld a, [$ffe1]
+	adc b
+	ld [$ffe1], a
+	
+	ld a, [$ff04] ; divider
+	ld b, a
+	ld a, [$ffe2]
+	sbc b
+	ld [$ffe2], a
+	
+; save bank
+	ld a, [$ff9d] ; current bank
+	ld [$ff8a], a
+	
+; scroll x
+	ld a, [$ffcf]
+	ld [$ff43], a ; scx
+; scroll y
+	ld a, [$ffd0]
+	ld [$ff42], a ; scy
+; window y
+	ld a, [$ffd2]
+	ld [$ff4a], a ; wy
+; window x + 7
+	ld a, [$ffd1]
+	ld [$ff4b], a ; wx
+	
+; some time management is in order
+; only have time for one of these during vblank
+	
+; bg map buffer has priority
+	call UpdateBGMapBuffer
+	jr c, .doneframeaction
+	
+; then pals
+	call UpdatePalsIfCGB
+	jr c, .doneframeaction
+	
+; dma transfer
+	call DMATransfer
+	jr c, .doneframeaction
+	
+; bg map
+	call UpdateBGMap
+	
+; these have their own timing checks
+	call SafeLoadTiles
+	call SafeLoadTiles2
+	call SafeTileAnimation
+	
+.doneframeaction
+; oam update off?
+	ld a, [$ffd8]
+	and a
+	jr nz, .vblankoccurred
+	
+; update oam by dma transfer
+	call $ff80
+;	403f:
+;		ld a, $c4
+;		ld [$ff46], a ; oam dma
+;		ld a, $28
+;	.loop
+;		dec a
+;		jr nz, .loop
+;		ret
+
+
+; vblank-sensitive operations are done
+	
+.vblankoccurred
+; tell other fns vblank happened
+	xor a
+	ld [VBlankOccurred], a
+	
+; dec $cfb1 until 0
+	ld a, [$cfb1]
+	and a
+	jr z, .textdelay
+	dec a
+	ld [$cfb1], a
+	
+.textdelay
+; dec text delay counter until 0
+	ld a, [TextDelayFrames]
+	and a
+	jr z, .joypad
+	dec a
+	ld [TextDelayFrames], a
+	
+.joypad
+	call Joypad
+	
+; update sound
+	ld a, BANK(UpdateSound)
+	rst Bankswitch ; bankswitch
+	call UpdateSound
+	ld a, [$ff8a]
+	rst Bankswitch ; restore bank
+	
+; 
+	ld a, [$ff98]
+	ld [$ffe3], a
+	
+	ret
+; 325
+
+
+VBlank2: ; 325
+; sound only
+
+; save bank
+	ld a, [$ff9d]
+	ld [$ff8a], a
+	
+; update sound
+	ld a, BANK(UpdateSound)
+	rst Bankswitch ; bankswitch
+	call UpdateSound
+	
+; restore bank
+	ld a, [$ff8a]
+	rst Bankswitch
+	
+; tell other fns vblank happened
+	xor a
+	ld [VBlankOccurred], a
+	ret
+; 337
+
+
+VBlank1: ; 337
+; scx, scy
+; palettes
+; bg map
+; tiles
+; oam
+; sound / lcd stat
+
+; save bank
+	ld a, [$ff9d]
+	ld [$ff8a], a
+	
+; scroll x
+	ld a, [$ffcf]
+	ld [$ff43], a ; scx
+	
+; scroll y
+	ld a, [$ffd0]
+	ld [$ff42], a ; scy
+	
+; time-sensitive fns
+	call UpdatePals
+	jr c, .vblankoccurred
+	
+; these have their own timing checks
+	call UpdateBGMap
+	call LoadTiles
+; update oam by dma transfer
+	call $ff80
+;	403f:
+;		ld a, $c4
+;		ld [$ff46], a ; oam dma
+;		ld a, $28
+;	.loop
+;		dec a
+;		jr nz, .loop
+;		ret
+	
+.vblankoccurred
+; tell other fns vblank happened
+	xor a
+	ld [VBlankOccurred], a
+	
+; get requested ints
+	ld a, [$ff0f] ; IF
+	ld b, a
+; discard requested ints
+	xor a
+	ld [$ff0f], a ; IF
+; enable lcd stat
+	ld a, %10 ; lcd stat
+	ld [$ffff], a ; IE
+; rerequest serial int if applicable (still disabled)
+; request lcd stat
+	ld a, b
+	and %1000 ; serial
+	or %10 ; lcd stat
+	ld [$ff0f], a ; IF
+	
+	ei
+; update sound
+	ld a, BANK(UpdateSound)
+	rst Bankswitch ; bankswitch
+	call UpdateSound
+; restore bank
+	ld a, [$ff8a]
+	rst Bankswitch
+	di
+	
+; get requested ints
+	ld a, [$ff0f] ; IF
+	ld b, a
+; discard requested ints
+	xor a
+	ld [$ff0f], a ; IF
+; enable ints besides joypad
+	ld a, %1111 ; serial timer lcdstat vblank
+	ld [$ffff], a ; IE
+; rerequest ints
+	ld a, b
+	ld [$ff0f], a ; IF
+	ret
+; 37f
+
+
+UpdatePals: ; 37f
+; update pals for either dmg or cgb
+
+; check cgb
+	ld a, [$ffe6]
+	and a
+	jp nz, UpdateCGBPals
+	
+; update gb pals
+	ld a, [$cfc7]
+	ld [$ff47], a ; BGP
+	
+	ld a, [$cfc8]
+	ld [$ff48], a ; OBP0
+	
+	ld a, [$cfc9]
+	ld [$ff49], a ; 0BP1
+	
+	and a
+	ret
+; 396
+
+
+VBlank3: ; 396
+; scx, scy
+; palettes
+; bg map
+; tiles
+; oam
+; sound / lcd stat
+
+; save bank
+	ld a, [$ff9d]
+	ld [$ff8a], a
+	
+; scroll x
+	ld a, [$ffcf]
+	ld [$ff43], a ; scx
+; scroll y
+	ld a, [$ffd0]
+	ld [$ff42], a ; scy
+	
+; any pals to update?
+	ld a, [$ffe5]
+	and a
+	call nz, ForceUpdateCGBPals
+	jr c, .vblankoccurred
+; else
+	call UpdateBGMap
+	call LoadTiles
+	
+; update oam by dma transfer
+	call $ff80
+;	403f:
+;		ld a, $c4 ; Sprites / $100
+;		ld [$ff46], a ; oam dma
+;		ld a, $28
+;	.loop
+;		dec a
+;		jr nz, .loop
+;		ret
+	
+.vblankoccurred
+; tell other fns vblank happened
+	xor a
+	ld [VBlankOccurred], a
+	
+; save int flag
+	ld a, [$ff0f] ; IF
+	push af
+; reset ints
+	xor a
+	ld [$ff0f], a ; IF
+; force lcdstat int during sound update
+	ld a, %10 ; lcd stat
+	ld [$ffff], a ; IE
+	ld [$ff0f], a ; IF
+	
+	ei
+; update sound
+	ld a, BANK(UpdateSound)
+	rst Bankswitch ; bankswitch
+	call UpdateSound
+; restore bank
+	ld a, [$ff8a]
+	rst Bankswitch
+	di
+	
+; request lcdstat
+	ld a, [$ff0f] ; IF
+	ld b, a
+; and any other ints
+	pop af
+	or b
+	ld b, a
+; reset ints
+	xor a
+	ld [$ff0f], a ; IF
+; enable ints besides joypad
+	ld a, %1111 ; serial timer lcdstat vblank
+	ld [$ffff], a ; IE
+; request ints
+	ld a, b
+	ld [$ff0f], a ; IF
+	ret
+; 3df
+
+
+VBlank4: ; 3df
+; bg map
+; tiles
+; oam
+; joypad
+; serial
+; sound
+
+; save bank
+	ld a, [$ff9d]
+	ld [$ff8a], a
+	
+	call UpdateBGMap
+	call SafeLoadTiles
+	
+; update oam by dma transfer
+	call $ff80
+;	403f:
+;		ld a, $c4
+;		ld [$ff46], a ; oam dma
+;		ld a, $28
+;	.loop
+;		dec a
+;		jr nz, .loop
+;		ret
+	
+; update joypad
+	call Joypad
+	
+; tell other fns vblank happened
+	xor a
+	ld [VBlankOccurred], a
+	
+; handshake
+	call AskSerial
+	
+; update sound
+	ld a, BANK(UpdateSound)
+	rst Bankswitch ; bankswitch
+	call UpdateSound
+; restore bank
+	ld a, [$ff8a]
+	rst Bankswitch
+	ret
+; 400
+
+
+VBlank5: ; 400
+; scx
+; palettes
+; bg map
+; tiles
+; joypad
+; 
+
+; save bank
+	ld a, [$ff9d]
+	ld [$ff8a], a
+	
+; scroll x
+	ld a, [$ffcf]
+	ld [$ff43], a ; scx
+	
+; if we can update pals, skip this part
+	call UpdatePalsIfCGB
+	jr c, .vblankoccurred
+	
+	call UpdateBGMap
+	call SafeLoadTiles
+	
+.vblankoccurred
+; tell other fns vblank happened
+	xor a
+	ld [VBlankOccurred], a
+	
+; joypad
+	call Joypad
+	
+; discard requested ints
+	xor a
+	ld [$ff0f], a ; IF
+; enable lcd stat
+	ld a, %10 ; lcd stat
+	ld [$ffff], a ; IE
+; request lcd stat
+	ld [$ff0f], a ; IF
+	
+	ei
+; update sound
+	ld a, BANK(UpdateSound)
+	rst Bankswitch ; bankswitch
+	call UpdateSound
+; restore bank
+	ld a, [$ff8a]
+	rst Bankswitch
+	di
+	
+; discard requested ints
+	xor a
+	ld [$ff0f], a ; IF
+; enable ints besides joypad
+	ld a, %1111 ; serial timer lcdstat vblank
+	ld [$ffff], a ; IE
+	ret
+; 436
+
+
+VBlank6: ; 436
+; palettes
+; tiles
+; dma transfer
+; sound
+
+; save bank
+	ld a, [$ff9d]
+	ld [$ff8a], a
+	
+; inc frame counter
+	ld hl, $ff9b
+	inc [hl]
+	
+	call UpdateCGBPals
+	jr c, .vblankoccurred
+	
+	call SafeLoadTiles
+	call SafeLoadTiles2
+	call DMATransfer
+	
+.vblankoccurred
+; tell other fns vblank happened
+	xor a
+	ld [VBlankOccurred], a
+	
+; update sound
+	ld a, BANK(UpdateSound)
+	rst Bankswitch ; bankswitch
+	call UpdateSound
+; restore bank
+	ld a, [$ff8a]
+	rst Bankswitch
+	ret
+; 45a