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IsTilePassable::
; sets carry if tile is passable, resets carry otherwise
homecall_sf _IsTilePassable
ret
FarCopyDataDouble::
; Expand bc bytes of 1bpp image data
; from a:de to 2bpp data at hl.
ld [wFarCopyDataSavedROMBank], a
ldh a, [hLoadedROMBank]
push af
ld a, [wFarCopyDataSavedROMBank]
call BankswitchCommon
ld a, h ; swap hl and de
ld h, d
ld d, a
ld a, l
ld l, e
ld e, a
ld a, b
and a
jr z, .eightbitcopyamount
ld a, c
and a ; multiple of $100
jr z, .expandloop ; if so, do not increment b because the first instance of dec c results in underflow
.eightbitcopyamount
inc b
.expandloop
ld a, [de]
inc de
ld [hli], a
ld [hli], a
dec c
jr nz, .expandloop
dec b
jr nz, .expandloop
pop af
call BankswitchCommon
ret
CopyVideoData::
; Wait for the next VBlank, then copy c 2bpp
; tiles from b:de to hl, 8 tiles at a time.
; This takes c/8 frames.
ldh a, [hAutoBGTransferEnabled]
push af
xor a ; disable auto-transfer while copying
ldh [hAutoBGTransferEnabled], a
ldh a, [hLoadedROMBank]
push af
ld a, b
call BankswitchCommon
ld a, e
ldh [hVBlankCopySource], a
ld a, d
ldh [hVBlankCopySource + 1], a
ld a, l
ldh [hVBlankCopyDest], a
ld a, h
ldh [hVBlankCopyDest + 1], a
.loop
ld a, c
cp 8
jr nc, .keepgoing
.done
ldh [hVBlankCopySize], a
call DelayFrame
pop af
call BankswitchCommon
pop af
ldh [hAutoBGTransferEnabled], a
ret
.keepgoing
ld a, 8
ldh [hVBlankCopySize], a
call DelayFrame
ld a, c
sub 8
ld c, a
jr .loop
CopyVideoDataDouble::
; Wait for the next VBlank, then copy c 1bpp
; tiles from b:de to hl, 8 tiles at a time.
; This takes c/8 frames.
ldh a, [hAutoBGTransferEnabled]
push af
xor a ; disable auto-transfer while copying
ldh [hAutoBGTransferEnabled], a
ldh a, [hLoadedROMBank]
push af
ld a, b
call BankswitchCommon
ld a, e
ldh [hVBlankCopyDoubleSource], a
ld a, d
ldh [hVBlankCopyDoubleSource + 1], a
ld a, l
ldh [hVBlankCopyDoubleDest], a
ld a, h
ldh [hVBlankCopyDoubleDest + 1], a
.loop
ld a, c
cp 8
jr nc, .keepgoing
.done
ldh [hVBlankCopyDoubleSize], a
call DelayFrame
pop af
call BankswitchCommon
pop af
ldh [hAutoBGTransferEnabled], a
ret
.keepgoing
ld a, 8
ldh [hVBlankCopyDoubleSize], a
call DelayFrame
ld a, c
sub 8
ld c, a
jr .loop
FillMemory::
push af
ld a, b
and a
jr z, .eightbitcopyamount
ld a, c
and a
jr z, .mulitpleof0x100
.eightbitcopyamount
inc b
.mulitpleof0x100
pop af
.loop
ld [hli], a
dec c
jr nz, .loop
dec b
jr nz, .loop
ret
GetFarByte::
; get a byte from a:hl
; and return it in a
push bc
ld b, a
ldh a, [hLoadedROMBank]
push af
ld a, b
call BankswitchCommon
ld b, [hl]
pop af
call BankswitchCommon
ld a, b
pop bc
ret
ClearScreenArea::
; Clear tilemap area cxb at hl.
ld a, " " ; blank tile
ld de, 20 ; screen width
.y
push hl
push bc
.x
ld [hli], a
dec c
jr nz, .x
pop bc
pop hl
add hl, de
dec b
jr nz, .y
ret
CopyScreenTileBufferToVRAM::
; Copy wTileMap to the BG Map starting at b * $100.
; This is done in thirds of 6 rows, so it takes 3 frames.
ld c, 6
ld hl, $600 * 0
decoord 0, 6 * 0
call .setup
call DelayFrame
ld hl, $600 * 1
decoord 0, 6 * 1
call .setup
call DelayFrame
ld hl, $600 * 2
decoord 0, 6 * 2
call .setup
jp DelayFrame
.setup
ld a, d
ldh [hVBlankCopyBGSource+1], a
call GetRowColAddressBgMap
ld a, l
ldh [hVBlankCopyBGDest], a
ld a, h
ldh [hVBlankCopyBGDest+1], a
ld a, c
ldh [hVBlankCopyBGNumRows], a
ld a, e
ldh [hVBlankCopyBGSource], a
ret
ClearScreen::
; Clear wTileMap, then wait
; for the bg map to update.
ld bc, 20 * 18
inc b
hlcoord 0, 0
ld a, " "
.loop
ld [hli], a
dec c
jr nz, .loop
dec b
jr nz, .loop
jp Delay3
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