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