Split more code out of home.asm.

1 files changed, 450 insertions, 0 deletions

diff --git a/home/vcopy.asm b/home/vcopy.asm
new file mode 100644
index 00000000..9f152841
--- /dev/null
+++ b/home/vcopy.asm
@@ -0,0 +1,450 @@
+; this function seems to be used only once
+; it store the address of a row and column of the VRAM background map in hl
+; INPUT: h - row, l - column, b - high byte of background tile map address in VRAM
+GetRowColAddressBgMap:: ; 1cdd (0:1cdd)
+	xor a
+	srl h
+	rr a
+	srl h
+	rr a
+	srl h
+	rr a
+	or l
+	ld l,a
+	ld a,b
+	or h
+	ld h,a
+	ret
+
+; clears a VRAM background map with blank space tiles
+; INPUT: h - high byte of background tile map address in VRAM
+ClearBgMap:: ; 1cf0 (0:1cf0)
+	ld a," "
+	jr .next
+	ld a,l
+.next
+	ld de,$400 ; size of VRAM background map
+	ld l,e
+.loop
+	ld [hli],a
+	dec e
+	jr nz,.loop
+	dec d
+	jr nz,.loop
+	ret
+
+; When the player takes a step, a row or column of 2x2 tile blocks at the edge
+; of the screen toward which they moved is exposed and has to be redrawn.
+; This function does the redrawing.
+RedrawExposedScreenEdge:: ; 1d01 (0:1d01)
+	ld a,[H_SCREENEDGEREDRAW]
+	and a
+	ret z
+	ld b,a
+	xor a
+	ld [H_SCREENEDGEREDRAW],a
+	dec b
+	jr nz,.redrawRow
+.redrawColumn
+	ld hl,wScreenEdgeTiles
+	ld a,[H_SCREENEDGEREDRAWADDR]
+	ld e,a
+	ld a,[H_SCREENEDGEREDRAWADDR + 1]
+	ld d,a
+	ld c,18 ; screen height
+.loop1
+	ld a,[hli]
+	ld [de],a
+	inc de
+	ld a,[hli]
+	ld [de],a
+	ld a,31
+	add e
+	ld e,a
+	jr nc,.noCarry
+	inc d
+.noCarry
+; the following 4 lines wrap us from bottom to top if necessary
+	ld a,d
+	and a,$03
+	or a,$98
+	ld d,a
+	dec c
+	jr nz,.loop1
+	xor a
+	ld [H_SCREENEDGEREDRAW],a
+	ret
+.redrawRow
+	ld hl,wScreenEdgeTiles
+	ld a,[H_SCREENEDGEREDRAWADDR]
+	ld e,a
+	ld a,[H_SCREENEDGEREDRAWADDR + 1]
+	ld d,a
+	push de
+	call .drawHalf ; draw upper half
+	pop de
+	ld a,32 ; width of VRAM background map
+	add e
+	ld e,a
+			 ; draw lower half
+.drawHalf
+	ld c,10
+.loop2
+	ld a,[hli]
+	ld [de],a
+	inc de
+	ld a,[hli]
+	ld [de],a
+	ld a,e
+	inc a
+; the following 6 lines wrap us from the right edge to the left edge if necessary
+	and a,$1f
+	ld b,a
+	ld a,e
+	and a,$e0
+	or b
+	ld e,a
+	dec c
+	jr nz,.loop2
+	ret
+
+; This function automatically transfers tile number data from the tile map at
+; wTileMap to VRAM during V-blank. Note that it only transfers one third of the
+; background per V-blank. It cycles through which third it draws.
+; This transfer is turned off when walking around the map, but is turned
+; on when talking to sprites, battling, using menus, etc. This is because
+; the above function, RedrawExposedScreenEdge, is used when walking to
+; improve efficiency.
+AutoBgMapTransfer:: ; 1d57 (0:1d57)
+	ld a,[H_AUTOBGTRANSFERENABLED]
+	and a
+	ret z
+	ld hl,[sp + 0]
+	ld a,h
+	ld [H_SPTEMP],a
+	ld a,l
+	ld [H_SPTEMP + 1],a ; save stack pinter
+	ld a,[H_AUTOBGTRANSFERPORTION]
+	and a
+	jr z,.transferTopThird
+	dec a
+	jr z,.transferMiddleThird
+.transferBottomThird
+	FuncCoord 0,12
+	ld hl,Coord
+	ld sp,hl
+	ld a,[H_AUTOBGTRANSFERDEST + 1]
+	ld h,a
+	ld a,[H_AUTOBGTRANSFERDEST]
+	ld l,a
+	ld de,(12 * 32)
+	add hl,de
+	xor a ; TRANSFERTOP
+	jr .doTransfer
+.transferTopThird
+	FuncCoord 0,0
+	ld hl,Coord
+	ld sp,hl
+	ld a,[H_AUTOBGTRANSFERDEST + 1]
+	ld h,a
+	ld a,[H_AUTOBGTRANSFERDEST]
+	ld l,a
+	ld a,TRANSFERMIDDLE
+	jr .doTransfer
+.transferMiddleThird
+	FuncCoord 0,6
+	ld hl,Coord
+	ld sp,hl
+	ld a,[H_AUTOBGTRANSFERDEST + 1]
+	ld h,a
+	ld a,[H_AUTOBGTRANSFERDEST]
+	ld l,a
+	ld de,(6 * 32)
+	add hl,de
+	ld a,TRANSFERBOTTOM
+.doTransfer
+	ld [H_AUTOBGTRANSFERPORTION],a ; store next portion
+	ld b,6
+
+TransferBgRows:: ; 1d9e (0:1d9e)
+; unrolled loop and using pop for speed
+
+	rept 20 / 2 - 1
+	pop de
+	ld [hl], e
+	inc l
+	ld [hl], d
+	inc l
+	endr
+
+	pop de
+	ld [hl], e
+	inc l
+	ld [hl], d
+
+i	ld a, 32 - (20 - 1)
+	add l
+	ld l, a
+	jr nc, .ok
+	inc h
+.ok
+	dec b
+	jr nz, TransferBgRows
+
+	ld a, [H_SPTEMP]
+	ld h, a
+	ld a, [H_SPTEMP + 1]
+	ld l, a
+	ld sp, hl
+	ret
+
+; Copies [H_VBCOPYBGNUMROWS] rows from H_VBCOPYBGSRC to H_VBCOPYBGDEST.
+; If H_VBCOPYBGSRC is XX00, the transfer is disabled.
+VBlankCopyBgMap:: ; 1de1 (0:1de1)
+	ld a,[H_VBCOPYBGSRC] ; doubles as enabling byte
+	and a
+	ret z
+	ld hl,[sp + 0]
+	ld a,h
+	ld [H_SPTEMP],a
+	ld a,l
+	ld [H_SPTEMP + 1],a ; save stack pointer
+	ld a,[H_VBCOPYBGSRC]
+	ld l,a
+	ld a,[H_VBCOPYBGSRC + 1]
+	ld h,a
+	ld sp,hl
+	ld a,[H_VBCOPYBGDEST]
+	ld l,a
+	ld a,[H_VBCOPYBGDEST + 1]
+	ld h,a
+	ld a,[H_VBCOPYBGNUMROWS]
+	ld b,a
+	xor a
+	ld [H_VBCOPYBGSRC],a ; disable transfer so it doesn't continue next V-blank
+	jr TransferBgRows
+
+
+VBlankCopyDouble::
+; Copy [H_VBCOPYDOUBLESIZE] 1bpp tiles
+; from H_VBCOPYDOUBLESRC to H_VBCOPYDOUBLEDEST.
+
+; While we're here, convert to 2bpp.
+; The process is straightforward:
+; copy each byte twice.
+
+	ld a, [H_VBCOPYDOUBLESIZE]
+	and a
+	ret z
+
+	ld hl, [sp + 0]
+	ld a, h
+	ld [H_SPTEMP], a
+	ld a, l
+	ld [H_SPTEMP + 1], a
+
+	ld a, [H_VBCOPYDOUBLESRC]
+	ld l, a
+	ld a, [H_VBCOPYDOUBLESRC + 1]
+	ld h, a
+	ld sp, hl
+
+	ld a, [H_VBCOPYDOUBLEDEST]
+	ld l, a
+	ld a, [H_VBCOPYDOUBLEDEST + 1]
+	ld h, a
+
+	ld a, [H_VBCOPYDOUBLESIZE]
+	ld b, a
+	xor a ; transferred
+	ld [H_VBCOPYDOUBLESIZE], a
+
+.loop
+	rept 3
+	pop de
+	ld [hl], e
+	inc l
+	ld [hl], e
+	inc l
+	ld [hl], d
+	inc l
+	ld [hl], d
+	inc l
+	endr
+
+	pop de
+	ld [hl], e
+	inc l
+	ld [hl], e
+	inc l
+	ld [hl], d
+	inc l
+	ld [hl], d
+	inc hl
+	dec b
+	jr nz, .loop
+
+	ld a, l
+	ld [H_VBCOPYDOUBLEDEST], a
+	ld a, h
+	ld [H_VBCOPYDOUBLEDEST + 1], a
+
+	ld hl, [sp + 0]
+	ld a, l
+	ld [H_VBCOPYDOUBLESRC], a
+	ld a, h
+	ld [H_VBCOPYDOUBLESRC + 1], a
+
+	ld a, [H_SPTEMP]
+	ld h, a
+	ld a, [H_SPTEMP + 1]
+	ld l, a
+	ld sp, hl
+
+	ret
+
+
+VBlankCopy::
+; Copy [H_VBCOPYSIZE] 2bpp tiles
+; from H_VBCOPYSRC to H_VBCOPYDEST.
+
+; Source and destination addresses
+; are updated, so transfer can
+; continue in subsequent calls.
+
+	ld a, [H_VBCOPYSIZE]
+	and a
+	ret z
+
+	ld hl, [sp + 0]
+	ld a, h
+	ld [H_SPTEMP], a
+	ld a, l
+	ld [H_SPTEMP + 1], a
+
+	ld a, [H_VBCOPYSRC]
+	ld l, a
+	ld a, [H_VBCOPYSRC + 1]
+	ld h, a
+	ld sp, hl
+
+	ld a, [H_VBCOPYDEST]
+	ld l, a
+	ld a, [H_VBCOPYDEST + 1]
+	ld h, a
+
+	ld a, [H_VBCOPYSIZE]
+	ld b, a
+	xor a ; transferred
+	ld [H_VBCOPYSIZE], a
+
+.loop
+	rept 7
+	pop de
+	ld [hl], e
+	inc l
+	ld [hl], d
+	inc l
+	endr
+
+	pop de
+	ld [hl], e
+	inc l
+	ld [hl], d
+	inc hl
+	dec b
+	jr nz, .loop
+
+	ld a, l
+	ld [H_VBCOPYDEST], a
+	ld a, h
+	ld [H_VBCOPYDEST + 1], a
+
+	ld hl, [sp + 0]
+	ld a, l
+	ld [H_VBCOPYSRC], a
+	ld a, h
+	ld [H_VBCOPYSRC + 1], a
+
+	ld a, [H_SPTEMP]
+	ld h, a
+	ld a, [H_SPTEMP + 1]
+	ld l, a
+	ld sp, hl
+
+	ret
+
+
+UpdateMovingBgTiles::
+; Animate water and flower
+; tiles in the overworld.
+
+	ld a, [$ffd7]
+	and a
+	ret z
+
+	ld a, [$ffd8]
+	inc a
+	ld [$ffd8], a
+	cp $14
+	ret c
+	cp $15
+	jr z, .flower
+
+	ld hl, vTileset + $14 * $10
+	ld c, $10
+
+	ld a, [wd085]
+	inc a
+	and 7
+	ld [wd085], a
+
+	and 4
+	jr nz, .left
+.right
+	ld a, [hl]
+	rrca
+	ld [hli], a
+	dec c
+	jr nz, .right
+	jr .done
+.left
+	ld a, [hl]
+	rlca
+	ld [hli], a
+	dec c
+	jr nz, .left
+.done
+	ld a, [$ffd7]
+	rrca
+	ret nc
+	xor a
+	ld [$ffd8], a
+	ret
+
+.flower
+	xor a
+	ld [$ffd8], a
+
+	ld a, [wd085]
+	and 3
+	cp 2
+	ld hl, FlowerTile1
+	jr c, .copy
+	ld hl, FlowerTile2
+	jr z, .copy
+	ld hl, FlowerTile3
+.copy
+	ld de, vTileset + $3 * $10
+	ld c, $10
+.loop
+	ld a, [hli]
+	ld [de], a
+	inc de
+	dec c
+	jr nz, .loop
+	ret
+
+FlowerTile1: INCBIN "gfx/tilesets/flower/flower1.2bpp"
+FlowerTile2: INCBIN "gfx/tilesets/flower/flower2.2bpp"
+FlowerTile3: INCBIN "gfx/tilesets/flower/flower3.2bpp"