From 4bc2564a6b217ef269c7c763b98fc4fb41967a97 Mon Sep 17 00:00:00 2001
From: yenatch <yenatch@gmail.com>
Date: Sat, 2 Feb 2013 07:14:56 -0500
Subject: VBlank and dependencies

VBlank has seven different modes. The one that sees the
most use is mode 0, which performs all basic display and
audio functions. The purpose of the others is unknown.

VBlank relies on the following functions:

-joypad
-cgb palette update
-dmg -> cgb pal conversion
-bg map update
-vram tile update
-tile animations
-serial request
-game timer

Tile animation is large enough to warrant its own commit.
---
 main.asm | 1547 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 1537 insertions(+), 10 deletions(-)

(limited to 'main.asm')

diff --git a/main.asm b/main.asm
index 8cc7d06cd..61fa45642 100644
--- a/main.asm
+++ b/main.asm
@@ -35,7 +35,7 @@ SECTION "rst38",HOME[$38] ; Unused
 	rst $38
 
 SECTION "vblank",HOME[$40] ; vblank interrupt
-	jp $0283
+	jp VBlank
 
 SECTION "lcd",HOME[$48] ; lcd interrupt
 	jp $0552
@@ -56,7 +56,541 @@ Start:
 
 SECTION "start",HOME[$150]
 
-INCBIN "baserom.gbc",$150,$45a - $150
+INCBIN "baserom.gbc",$150,$283 - $150
+
+VBlank: ; 283
+	push af
+	push bc
+	push de
+	push hl
+	
+; get vblank type
+	ld a, [$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
+
 
 DelayFrame: ; 0x45a
 ; delay for one frame
@@ -369,10 +903,8 @@ FixTime: ; 61d
 	ret
 ; 658
 
-
 INCBIN "baserom.gbc",$658,$691 - $658
 
-
 SetClock: ; 691
 ; set clock data from hram
 
@@ -421,7 +953,87 @@ SetClock: ; 691
 	ret
 ; 6c4
 
-INCBIN "baserom.gbc",$6c4,$984 - $6c4
+INCBIN "baserom.gbc",$6c4,$935 - $6c4
+
+Joypad: ; 935
+; update joypad state
+; $ffa2: released
+; $ffa3: pressed
+; $ffa4: input
+; $ffa5: total pressed
+
+; 
+	ld a, [$cfbe]
+	and $d0
+	ret nz
+	
+; pause game update?
+	ld a, [$c2cd]
+	and a
+	ret nz
+	
+; d-pad
+	ld a, $20
+	ld [$ff00], a
+	ld a, [$ff00]
+	ld a, [$ff00]
+; hi nybble
+	cpl
+	and $f
+	swap a
+	ld b, a
+	
+; buttons
+	ld a, $10
+	ld [$ff00], a
+; wait to stabilize
+	ld a, [$ff00]
+	ld a, [$ff00]
+	ld a, [$ff00]
+	ld a, [$ff00]
+	ld a, [$ff00]
+	ld a, [$ff00]
+; lo nybble
+	cpl
+	and $f
+	or b
+	ld b, a
+	
+; reset joypad
+	ld a, $30
+	ld [$ff00], a
+	
+; get change in input
+	ld a, [$ffa4] ; last frame's input
+	ld e, a
+	xor b ; current frame input
+	ld d, a
+; released
+	and e
+	ld [$ffa2], a
+; pressed
+	ld a, d
+	and b
+	ld [$ffa3], a
+	
+; total pressed
+	ld c, a
+	ld a, [$ffa5]
+	or c
+	ld [$ffa5], a
+	
+; original input
+	ld a, b
+	ld [$ffa4], a
+	
+; A+B+SELECT+START
+	and $f
+	cp $f
+	jp z, $0150 ; reset
+	
+	ret
+; 984
+
 
 GetJoypadPublic: ; 984
 ; update mirror joypad input from $ffa4 (real input)
@@ -588,7 +1200,136 @@ StopAutoInput: ; a0a
 	ret
 ; a1b
 
-INCBIN "baserom.gbc",$a1b,$c9f - $a1b
+INCBIN "baserom.gbc",$a1b,$c2f - $a1b
+
+UpdatePalsIfCGB: ; c2f
+; update bgp data from BGPals
+; update obp data from OBPals
+; return carry if successful
+
+; check cgb
+	ld a, [$ffe6]
+	and a
+	ret z
+	
+UpdateCGBPals: ; c33
+; return carry if successful
+; any pals to update?
+	ld a, [$ffe5]
+	and a
+	ret z
+	
+ForceUpdateCGBPals: ; c37
+; save wram bank
+	ld a, [$ff70] ; wram bank
+	push af
+; bankswitch
+	ld a, 5 ; BANK(BGPals)
+	ld [$ff70], a ; wram bank
+; get bg pal buffer
+	ld hl, BGPals ; 5:d080
+	
+; update bg pals
+	ld a, %10000000 ; auto increment, index 0
+	ld [$ff68], a ; BGPI
+	ld c, $69 ; $ff69
+	ld b, 4 ; NUM_PALS / 2
+	
+.bgp
+; copy 16 bytes (8 colors / 2 pals) to bgpd
+	ld a, [hli]
+	ld [$ff00+c], a
+	ld a, [hli]
+	ld [$ff00+c], a
+	ld a, [hli]
+	ld [$ff00+c], a
+	ld a, [hli]
+	ld [$ff00+c], a
+	ld a, [hli]
+	ld [$ff00+c], a
+	ld a, [hli]
+	ld [$ff00+c], a
+	ld a, [hli]
+	ld [$ff00+c], a
+	ld a, [hli]
+	ld [$ff00+c], a
+	ld a, [hli]
+	ld [$ff00+c], a
+	ld a, [hli]
+	ld [$ff00+c], a
+	ld a, [hli]
+	ld [$ff00+c], a
+	ld a, [hli]
+	ld [$ff00+c], a
+	ld a, [hli]
+	ld [$ff00+c], a
+	ld a, [hli]
+	ld [$ff00+c], a
+	ld a, [hli]
+	ld [$ff00+c], a
+	ld a, [hli]
+	ld [$ff00+c], a
+; done?
+	dec b
+	jr nz, .bgp
+	
+; hl is now 5:d0c0 OBPals
+	
+; update obj pals
+	ld a, %10000000 ; auto increment, index 0
+	ld [$ff6a], a
+	ld c, $6b ; $ff6b - $ff00
+	ld b, 4 ; NUM_PALS / 2
+	
+.obp
+; copy 16 bytes (8 colors / 2 pals) to obpd
+	ld a, [hli]
+	ld [$ff00+c], a
+	ld a, [hli]
+	ld [$ff00+c], a
+	ld a, [hli]
+	ld [$ff00+c], a
+	ld a, [hli]
+	ld [$ff00+c], a
+	ld a, [hli]
+	ld [$ff00+c], a
+	ld a, [hli]
+	ld [$ff00+c], a
+	ld a, [hli]
+	ld [$ff00+c], a
+	ld a, [hli]
+	ld [$ff00+c], a
+	ld a, [hli]
+	ld [$ff00+c], a
+	ld a, [hli]
+	ld [$ff00+c], a
+	ld a, [hli]
+	ld [$ff00+c], a
+	ld a, [hli]
+	ld [$ff00+c], a
+	ld a, [hli]
+	ld [$ff00+c], a
+	ld a, [hli]
+	ld [$ff00+c], a
+	ld a, [hli]
+	ld [$ff00+c], a
+	ld a, [hli]
+	ld [$ff00+c], a
+; done?
+	dec b
+	jr nz, .obp
+	
+; restore wram bank
+	pop af
+	ld [$ff70], a ; wram bank
+; clear pal update queue
+	xor a
+	ld [$ffe5], a
+; successfully updated palettes
+	scf
+	ret
+; c9f
+
 
 DmgToCgbBGPals: ; c9f
 ; exists to forego reinserting cgb-converted image data
@@ -1074,7 +1815,617 @@ Char5F: ; 0x1356
 	pop hl
 	ret
 
-INCBIN "baserom.gbc",$135a,$185d - $135a
+INCBIN "baserom.gbc",$135a,$15d8 - $135a
+
+DMATransfer: ; 15d8
+; DMA transfer
+; return carry if successful
+
+; anything to transfer?
+	ld a, [$ffe8]
+	and a
+	ret z
+; start transfer
+	ld [$ff55], a ; hdma5
+; indicate that transfer has occurred
+	xor a
+	ld [$ffe8], a
+; successful transfer
+	scf
+	ret
+; 15e3
+
+
+UpdateBGMapBuffer: ; 15e3
+; write [$ffdc] 16x8 tiles from BGMapBuffer to bg map addresses in BGMapBufferPtrs
+; [$ffdc] must be even since this is done in 16x16 blocks
+
+; return carry if successful
+
+; any tiles to update?
+	ld a, [$ffdb]
+	and a
+	ret z
+; save wram bank
+	ld a, [$ff4f] ; vram bank
+	push af
+; save sp
+	ld [$ffd9], sp
+	
+; temp stack
+	ld hl, BGMapBufferPtrs
+	ld sp, hl
+; we can now pop the addresses of affected spots in bg map
+	
+; get pal and tile buffers
+	ld hl, BGMapPalBuffer
+	ld de, BGMapBuffer
+
+.loop
+; draw one 16x16 block
+
+; top half:
+
+; get bg map address
+	pop bc
+; update palettes
+	ld a, $1
+	ld [$ff4f], a ; vram bank
+; tile 1
+	ld a, [hli]
+	ld [bc], a
+	inc c
+; tile 2
+	ld a, [hli]
+	ld [bc], a
+	dec c
+; update tiles
+	ld a, $0
+	ld [$ff4f], a ; vram bank
+; tile 1
+	ld a, [de]
+	inc de
+	ld [bc], a
+	inc c
+; tile 2
+	ld a, [de]
+	inc de
+	ld [bc], a
+	
+; bottom half:
+
+; get bg map address
+	pop bc
+; update palettes
+	ld a, $1
+	ld [$ff4f], a ; vram bank
+; tile 1
+	ld a, [hli]
+	ld [bc], a
+	inc c
+; tile 2
+	ld a, [hli]
+	ld [bc], a
+	dec c
+; update tiles
+	ld a, $0
+	ld [$ff4f], a ; vram bank
+; tile 1
+	ld a, [de]
+	inc de
+	ld [bc], a
+	inc c
+; tile 2
+	ld a, [de]
+	inc de
+	ld [bc], a
+	
+; we've done 2 16x8 blocks
+	ld a, [$ffdc]
+	dec a
+	dec a
+	ld [$ffdc], a
+	
+; if there are more left, get the next 16x16 block
+	jr nz, .loop
+	
+	
+; restore sp
+	ld a, [$ffd9]
+	ld l, a
+	ld a, [$ffda]
+	ld h, a
+	ld sp, hl
+	
+; restore vram bank
+	pop af
+	ld [$ff4f], a ; vram bank
+	
+; we don't need to update bg map until new tiles are loaded
+	xor a
+	ld [$ffdb], a
+	
+; successfully updated bg map
+	scf
+	ret
+; 163a
+
+
+WaitTop: ; 163a
+	ld a, [$ffd4]
+	and a
+	ret z
+	
+; wait until top third of bg map can be updated
+	ld a, [$ffd5]
+	and a
+	jr z, .quit
+	
+	call DelayFrame
+	jr WaitTop
+	
+.quit
+	xor a
+	ld [$ffd4], a
+	ret
+; 164c
+
+
+UpdateBGMap: ; 164c
+; get mode
+	ld a, [$ffd4]
+	and a
+	ret z
+	
+; don't save bg map address
+	dec a ; 1
+	jr z, .tiles
+	dec a ; 2
+	jr z, .attr
+	dec a ; ?
+	
+; save bg map address
+	ld a, [$ffd6]
+	ld l, a
+	ld a, [$ffd7]
+	ld h, a
+	push hl
+
+; bg map 1 ($9c00)
+	xor a
+	ld [$ffd6], a
+	ld a, $9c
+	ld [$ffd7], a
+	
+; get mode again
+	ld a, [$ffd4]
+	push af
+	cp 3
+	call z, .tiles
+	pop af
+	cp 4
+	call z, .attr
+	
+; restore bg map address
+	pop hl
+	ld a, l
+	ld [$ffd6], a
+	ld a, h
+	ld [$ffd7], a
+	ret
+	
+.attr
+; switch vram banks
+	ld a, 1
+	ld [$ff4f], a ; vram bank
+; bg map 1
+	ld hl, AttrMap
+	call .getthird
+; restore vram bank
+	ld a, 0
+	ld [$ff4f], a ; vram bank
+	ret
+	
+.tiles
+; bg map 0
+	ld hl, TileMap
+	
+.getthird
+; save sp
+	ld [$ffd9], sp
+	
+; # tiles to move down * 6 (which third?)
+	ld a, [$ffd5]
+	and a ; 0
+	jr z, .top
+	dec a ; 1
+	jr z, .middle
+
+; .bottom ; 2
+; move 12 tiles down
+	ld de, $00f0 ; TileMap(0,12) - TileMap
+	add hl, de
+; stack now points to source
+	ld sp, hl
+; get bg map address
+	ld a, [$ffd7]
+	ld h, a
+	ld a, [$ffd6]
+	ld l, a
+; move 12 tiles down
+	ld de, $0180 ; bgm(0,12)
+	add hl, de
+; start at top next time
+	xor a
+	jr .start
+	
+.middle
+; move 6 tiles down
+	ld de, $0078 ; TileMap(0,6) - TileMap
+	add hl, de
+; stack now points to source
+	ld sp, hl
+; get bg map address
+	ld a, [$ffd7]
+	ld h, a
+	ld a, [$ffd6]
+	ld l, a
+; move 6 tiles down
+	ld de, $00c0 ; bgm(0,6)
+	add hl, de
+; start at bottom next time
+	ld a, 2
+	jr .start
+	
+.top
+; stack now points to source
+	ld sp, hl
+; get bg map address
+	ld a, [$ffd7]
+	ld h, a
+	ld a, [$ffd6]
+	ld l, a
+; start at middle next time
+	ld a, 1
+	
+.start
+; which third to draw next update
+	ld [$ffd5], a
+; # rows per third
+	ld a, 6 ; SCREEN_HEIGHT / 3
+; # tiles from the edge of the screen to the next row
+	ld bc, $000d ; BG_WIDTH + 1 - SCREEN_WIDTH
+	
+.row
+; write a row of 20 tiles
+	pop de
+	ld [hl], e
+	inc l
+	ld [hl], d
+	inc l
+	pop de
+	ld [hl], e
+	inc l
+	ld [hl], d
+	inc l
+	pop de
+	ld [hl], e
+	inc l
+	ld [hl], d
+	inc l
+	pop de
+	ld [hl], e
+	inc l
+	ld [hl], d
+	inc l
+	pop de
+	ld [hl], e
+	inc l
+	ld [hl], d
+	inc l
+	pop de
+	ld [hl], e
+	inc l
+	ld [hl], d
+	inc l
+	pop de
+	ld [hl], e
+	inc l
+	ld [hl], d
+	inc l
+	pop de
+	ld [hl], e
+	inc l
+	ld [hl], d
+	inc l
+	pop de
+	ld [hl], e
+	inc l
+	ld [hl], d
+	inc l
+	pop de
+	ld [hl], e
+	inc l
+	ld [hl], d
+; next row
+	add hl, bc
+; done?
+	dec a
+	jr nz, .row
+	
+; restore sp
+	ld a, [$ffd9]
+	ld l, a
+	ld a, [$ffda]
+	ld h, a
+	ld sp, hl
+	ret
+; 170a
+
+
+SafeLoadTiles2: ; 170a
+; only execute during first fifth of vblank
+; any tiles to draw?
+	ld a, [$cf6c]
+	and a
+	ret z
+; abort if too far into vblank
+	ld a, [$ff44] ; LY
+; ly = 144-145?
+	cp 144
+	ret c
+	cp 146
+	ret nc
+	
+GetTiles2: ; 1717
+; load [$cf6c] tiles from [$cf6d-e] to [$cf6f-70]
+; save sp
+	ld [$ffd9], sp
+	
+; sp = [$cf6d-e] tile source
+	ld hl, $cf6d
+	ld a, [hli]
+	ld h, [hl]
+	ld l, a
+	ld sp, hl
+	
+; hl = [$cf6f-70] tile dest
+	ld hl, $cf6f
+	ld a, [hli]
+	ld h, [hl]
+	ld l, a
+	
+; # tiles to draw
+	ld a, [$cf6c]
+	ld b, a
+	
+; clear tile queue
+	xor a
+	ld [$cf6c], a
+	
+.loop
+; put 1 tile (16 bytes) into hl from sp
+	pop de
+	ld [hl], e
+	inc l
+	ld [hl], e
+	inc l
+	ld [hl], d
+	inc l
+	ld [hl], d
+	inc l
+	pop de
+	ld [hl], e
+	inc l
+	ld [hl], e
+	inc l
+	ld [hl], d
+	inc l
+	ld [hl], d
+	inc l
+	pop de
+	ld [hl], e
+	inc l
+	ld [hl], e
+	inc l
+	ld [hl], d
+	inc l
+	ld [hl], d
+	inc l
+	pop de
+	ld [hl], e
+	inc l
+	ld [hl], e
+	inc l
+	ld [hl], d
+	inc l
+	ld [hl], d
+; next tile
+	inc hl
+; done?
+	dec b
+	jr nz, .loop
+	
+; update $cf6f-70
+	ld a, l
+	ld [$cf6f], a
+	ld a, h
+	ld [$cf70], a
+	
+; update $cf6d-e
+	ld [$cf6d], sp
+	
+; restore sp
+	ld a, [$ffd9]
+	ld l, a
+	ld a, [$ffda]
+	ld h, a
+	ld sp, hl
+	ret
+; 1769
+
+
+SafeLoadTiles: ; 1769
+; only execute during first fifth of vblank
+; any tiles to draw?
+	ld a, [$cf67]
+	and a
+	ret z
+; abort if too far into vblank
+	ld a, [$ff44] ; LY
+; ly = 144-145?
+	cp 144
+	ret c
+	cp 146
+	ret nc
+	jr GetTiles
+	
+LoadTiles: ; 1778
+; use only if time is allotted
+; any tiles to draw?
+	ld a, [$cf67]
+	and a
+	ret z
+; get tiles
+	
+GetTiles: ; 177d
+; load [$cf67] tiles from [$cf68-9] to [$cf6a-b]
+
+; save sp
+	ld [$ffd9], sp
+	
+; sp = [$cf68-9] tile source
+	ld hl, $cf68
+	ld a, [hli]
+	ld h, [hl]
+	ld l, a
+	ld sp, hl
+	
+; hl = [$cf6a-b] tile dest
+	ld hl, $cf6a
+	ld a, [hli]
+	ld h, [hl]
+	ld l, a
+	
+; # tiles to draw
+	ld a, [$cf67]
+	ld b, a
+; clear tile queue
+	xor a
+	ld [$cf67], a
+	
+.loop
+; put 1 tile (16 bytes) into hl from sp
+	pop de
+	ld [hl], e
+	inc l
+	ld [hl], d
+	inc l
+	pop de
+	ld [hl], e
+	inc l
+	ld [hl], d
+	inc l
+	pop de
+	ld [hl], e
+	inc l
+	ld [hl], d
+	inc l
+	pop de
+	ld [hl], e
+	inc l
+	ld [hl], d
+	inc l
+	pop de
+	ld [hl], e
+	inc l
+	ld [hl], d
+	inc l
+	pop de
+	ld [hl], e
+	inc l
+	ld [hl], d
+	inc l
+	pop de
+	ld [hl], e
+	inc l
+	ld [hl], d
+	inc l
+	pop de
+	ld [hl], e
+	inc l
+	ld [hl], d
+; next tile
+	inc hl
+; done?
+	dec b
+	jr nz, .loop
+	
+; update $cf6a-b
+	ld a, l
+	ld [$cf6a], a
+	ld a, h
+	ld [$cf6b], a
+	
+; update $cf68-9
+	ld [$cf68], sp
+	
+; restore sp
+	ld a, [$ffd9]
+	ld l, a
+	ld a, [$ffda]
+	ld h, a
+	ld sp, hl
+	ret
+; 17d3
+
+
+SafeTileAnimation: ; 17d3
+; call from vblank
+
+	ld a, [$ffde]
+	and a
+	ret z
+	
+; abort if too far into vblank
+	ld a, [$ff44] ; LY
+; ret unless ly = 144-150
+	cp 144
+	ret c
+	cp 151
+	ret nc
+	
+; save affected banks
+; switch to new banks
+	ld a, [$ff9d]
+	push af ; save bank
+	ld a, BANK(DoTileAnimation)
+	rst Bankswitch ; bankswitch
+
+	ld a, [$ff70] ; wram bank
+	push af ; save wram bank
+	ld a, $1 ; wram bank 1
+	ld [$ff70], a ; wram bank
+
+	ld a, [$ff4f] ; vram bank
+	push af ; save vram bank
+	ld a, $0 ; vram bank 0
+	ld [$ff4f], a ; vram bank
+	
+; take care of tile animation queue
+	call DoTileAnimation
+	
+; restore affected banks
+	pop af
+	ld [$ff4f], a ; vram bank
+	pop af
+	ld [$ff70], a ; wram bank
+	pop af
+	rst Bankswitch ; bankswitch
+	ret
+; 17ff
+
+INCBIN "baserom.gbc",$17ff,$185d - $17ff
 
 GetTileType: ; 185d
 ; checks the properties of a tile
@@ -1099,7 +2450,177 @@ GetTileType: ; 185d
 	ret
 ; 1875
 
-INCBIN "baserom.gbc",$1875,$261f - $1875
+INCBIN "baserom.gbc",$1875,$2063 - $1875
+
+AskSerial: ; 2063
+; send out a handshake while serial int is off
+	ld a, [$c2d4]
+	bit 0, a
+	ret z
+	
+	ld a, [$c2d5]
+	and a
+	ret nz
+	
+; once every 6 frames
+	ld hl, $ca8a
+	inc [hl]
+	ld a, [hl]
+	cp 6
+	ret c
+	
+	xor a
+	ld [hl], a
+	
+	ld a, $c
+	ld [$c2d5], a
+	
+; handshake
+	ld a, $88
+	ld [$ff01], a
+	
+; switch to internal clock
+	ld a, %00000001
+	ld [$ff02], a
+	
+; start transfer
+	ld a, %10000001
+	ld [$ff02], a
+	
+	ret
+; 208a
+
+INCBIN "baserom.gbc",$208a,$209e - $208a
+
+GameTimer: ; 209e
+; precautionary
+	nop
+	
+; save wram bank
+	ld a, [$ff70] ; wram bank
+	push af
+	
+	ld a, $1
+	ld [$ff70], a ; wram bank
+	
+	call UpdateGameTimer
+	
+; restore wram bank
+	pop af
+	ld [$ff70], a ; wram bank
+	ret
+; 20ad
+
+
+UpdateGameTimer: ; 20ad
+; increment the game timer by one frame
+; capped at 999:59:59.00 after exactly 1000 hours
+
+; pause game update?
+	ld a, [$c2cd]
+	and a
+	ret nz
+	
+; game timer paused?
+	ld hl, GameTimerPause
+	bit 0, [hl]
+	ret z
+	
+; reached cap? (999:00:00.00)
+	ld hl, GameTimeCap
+	bit 0, [hl]
+	ret nz
+	
+; increment frame counter
+	ld hl, GameTimeFrames ; frame counter
+	ld a, [hl]
+	inc a
+
+; reached 1 second?
+	cp 60 ; frames/second
+	jr nc, .second ; 20c5 $2
+	
+; update frame counter
+	ld [hl], a
+	ret
+	
+.second
+; reset frame counter
+	xor a
+	ld [hl], a
+	
+; increment second counter
+	ld hl, GameTimeSeconds
+	ld a, [hl]
+	inc a
+	
+; reached 1 minute?
+	cp 60 ; seconds/minute
+	jr nc, .minute
+	
+; update second counter
+	ld [hl], a
+	ret
+	
+.minute
+; reset second counter
+	xor a
+	ld [hl], a
+	
+; increment minute counter
+	ld hl, GameTimeMinutes
+	ld a, [hl]
+	inc a
+	
+; reached 1 hour?
+	cp 60 ; minutes/hour
+	jr nc, .hour
+	
+; update minute counter
+	ld [hl], a
+	ret
+	
+.hour
+; reset minute counter
+	xor a
+	ld [hl], a
+	
+; increment hour counter
+	ld a, [GameTimeHours]
+	ld h, a
+	ld a, [GameTimeHours+1]
+	ld l, a
+	inc hl
+	
+; reached 1000 hours?
+	ld a, h
+	cp $3 ; 1000 / $100
+	jr c, .updatehr
+	
+	ld a, l
+	cp $e8 ; 1000 & $ff
+	jr c, .updatehr
+	
+; cap at 999:59:59.00
+	ld hl, GameTimeCap
+	set 0, [hl] ; stop timer
+	
+	ld a, 59
+	ld [GameTimeMinutes], a
+	ld [GameTimeSeconds], a
+	
+; this will never be run again
+	ret
+	
+.updatehr
+	ld a, h
+	ld [GameTimeHours], a
+	ld a, l
+	ld [GameTimeHours+1], a
+	ret
+; 210f
+
+INCBIN "baserom.gbc",$210f,$261f - $210f
 
 PushScriptPointer: ; 261f
 ; used to call a script from asm
@@ -1496,7 +3017,11 @@ CloseSRAM: ; 2fe1
 	ret
 ; 2fec
 
-INCBIN "baserom.gbc",$2fec,$300b-$2fec
+JpHl: ; 2fec
+	jp [hl]
+; 2fed
+
+INCBIN "baserom.gbc",$2fed,$300b-$2fed
 
 ClearSprites: ; 300b
 	ld hl, Sprites
@@ -2399,7 +3924,7 @@ SFXChannelsOff: ; 3e21
 	ret
 ; 3e32
 
-INCBIN "baserom.gbc",$3e32,$4000 - $3e32
+INCBIN "baserom.gbc",$3e32,$3fb5 - $3e32
 
 SECTION "bank1",DATA,BANK[$1]
 
@@ -89886,6 +91411,8 @@ INCBIN "baserom.gbc",$FBCCF,$fc000-$fbccf
 
 SECTION "bank3F",DATA,BANK[$3F]
 
+DoTileAnimation:
+
 INCBIN "baserom.gbc",$FC000,$fcdc2-$fc000
 
 LoadTradesPointer: ; 0xfcdc2
-- 
cgit v1.2.3


From ec66551519195ee81176b7a07d5fb6871d96112d Mon Sep 17 00:00:00 2001
From: yenatch <yenatch@gmail.com>
Date: Sat, 2 Feb 2013 08:00:50 -0500
Subject: Decompression function

---
 main.asm | 372 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 371 insertions(+), 1 deletion(-)

(limited to 'main.asm')

diff --git a/main.asm b/main.asm
index 61fa45642..8dc9d6a72 100644
--- a/main.asm
+++ b/main.asm
@@ -1200,7 +1200,377 @@ StopAutoInput: ; a0a
 	ret
 ; a1b
 
-INCBIN "baserom.gbc",$a1b,$c2f - $a1b
+INCBIN "baserom.gbc",$a1b,$b40 - $a1b
+
+FarDecompress: ; b40
+; Decompress graphics data at a:hl to de
+
+; put a away for a sec
+	ld [$c2c4], a
+; save bank
+	ld a, [$ff9d]
+	push af
+; bankswitch
+	ld a, [$c2c4]
+	rst Bankswitch
+	
+; what we came here for
+	call Decompress
+	
+; restore bank
+	pop af
+	rst Bankswitch
+	ret
+; b50
+
+
+Decompress: ; b50
+; Pokemon Crystal uses an lz variant for compression.
+
+; This is mainly used for graphics, but the intro's
+; tilemaps also use this compression.
+
+; This function decompresses lz-compressed data at hl to de.
+
+
+; Basic rundown:
+
+;	A typical control command consists of:
+;		-the command (bits 5-7)
+;		-the count (bits 0-4)
+;		-and any additional params
+
+;	$ff is used as a terminator.
+
+
+;	Commands:
+
+;		0: literal
+;			literal data for some number of bytes
+;		1: iterate
+;			one byte repeated for some number of bytes
+;		2: alternate
+;			two bytes alternated for some number of bytes
+;		3: zero (whitespace)
+;			0x00 repeated for some number of bytes
+
+;	Repeater control commands have a signed parameter used to determine the start point.
+;	Wraparound is simulated:
+;		Positive values are added to the start address of the decompressed data
+;		and negative values are subtracted from the current position.
+
+;		4: repeat
+;			repeat some number of bytes from decompressed data
+;		5: flipped
+;			repeat some number of flipped bytes from decompressed data
+;			ex: $ad = %10101101 -> %10110101 = $b5
+;		6: reverse
+;			repeat some number of bytes in reverse from decompressed data
+
+;	If the value in the count needs to be larger than 5 bits,
+;	control code 7 can be used to expand the count to 10 bits.
+
+;		A new control command is read in bits 2-4.
+;		The new 10-bit count is split:
+;			bits 0-1 contain the top 2 bits
+;			another byte is added containing the latter 8
+
+;		So, the structure of the control command becomes:
+;			111xxxyy yyyyyyyy
+;			 |  |  |    |
+;            |  | our new count
+;            | the control command for this count
+;            7 (this command)
+
+; For more information, refer to the code below and in extras/gfx.py .
+
+; save starting output address
+	ld a, e
+	ld [$c2c2], a
+	ld a, d
+	ld [$c2c3], a
+	
+.loop
+; get next byte
+	ld a, [hl]
+; done?
+	cp $ff ; end
+	ret z
+
+; get control code
+	and %11100000
+	
+; 10-bit param?
+	cp $e0 ; LZ_HI
+	jr nz, .normal
+	
+	
+; 10-bit param:
+
+; get next 3 bits (%00011100)
+	ld a, [hl]
+	add a
+	add a ; << 3
+	add a
+	
+; this is our new control code
+	and %11100000
+	push af
+	
+; get param hi
+	ld a, [hli]
+	and %00000011
+	ld b, a
+	
+; get param lo
+	ld a, [hli]
+	ld c, a
+	
+; read at least 1 byte
+	inc bc
+	jr .readers
+	
+	
+.normal
+; push control code
+	push af
+; get param
+	ld a, [hli]
+	and %00011111
+	ld c, a
+	ld b, $0
+; read at least 1 byte
+	inc c
+	
+.readers
+; let's get started
+
+; inc loop counts since we bail as soon as they hit 0
+	inc b
+	inc c
+	
+; get control code
+	pop af
+; command type
+	bit 7, a ; 80, a0, c0
+	jr nz, .repeatertype
+	
+; literals
+	cp $20 ; LZ_ITER
+	jr z, .iter
+	cp $40 ; LZ_ALT
+	jr z, .alt
+	cp $60 ; LZ_ZERO
+	jr z, .zero
+	; else $00
+	
+; 00 ; LZ_LIT
+; literal data for bc bytes
+.loop1
+; done?
+	dec c
+	jr nz, .next1
+	dec b
+	jp z, .loop
+	
+.next1
+	ld a, [hli]
+	ld [de], a
+	inc de
+	jr .loop1
+	
+	
+; 20 ; LZ_ITER
+; write byte for bc bytes
+.iter
+	ld a, [hli]
+	
+.iterloop
+	dec c
+	jr nz, .iternext
+	dec b
+	jp z, .loop
+	
+.iternext
+	ld [de], a
+	inc de
+	jr .iterloop
+	
+	
+; 40 ; LZ_ALT
+; alternate two bytes for bc bytes
+
+; next pair
+.alt
+; done?
+	dec c
+	jr nz, .alt0
+	dec b
+	jp z, .altclose0
+	
+; alternate for bc
+.alt0
+	ld a, [hli]
+	ld [de], a
+	inc de
+	dec c
+	jr nz, .alt1
+; done?
+	dec b
+	jp z, .altclose1
+.alt1
+	ld a, [hld]
+	ld [de], a
+	inc de
+	jr .alt
+	
+; skip past the bytes we were alternating
+.altclose0
+	inc hl
+.altclose1
+	inc hl
+	jr .loop
+	
+	
+; 60 ; LZ_ZERO
+; write 00 for bc bytes
+.zero
+	xor a
+	
+.zeroloop
+	dec c
+	jr nz, .zeronext
+	dec b
+	jp z, .loop
+	
+.zeronext
+	ld [de], a
+	inc de
+	jr .zeroloop
+	
+	
+; repeats
+; 80, a0, c0
+; repeat decompressed data from output
+.repeatertype
+	push hl
+	push af
+; get next byte
+	ld a, [hli]
+; absolute?
+	bit 7, a
+	jr z, .absolute
+	
+; relative
+; a = -a
+	and %01111111 ; forget the bit we just looked at
+	cpl
+; add de (current output address)
+	add e
+	ld l, a
+	ld a, $ff ; -1
+	adc d
+	ld h, a
+	jr .repeaters
+	
+.absolute
+; get next byte (lo)
+	ld l, [hl]
+; last byte (hi)
+	ld h, a
+; add starting output address
+	ld a, [$c2c2]
+	add l
+	ld l, a
+	ld a, [$c2c3]
+	adc h
+	ld h, a
+	
+.repeaters
+	pop af
+	cp $80 ; LZ_REPEAT
+	jr z, .repeat
+	cp $a0 ; LZ_FLIP
+	jr z, .flip
+	cp $c0 ; LZ_REVERSE
+	jr z, .reverse
+	
+; e0 -> 80
+	
+; 80 ; LZ_REPEAT
+; repeat some decompressed data
+.repeat
+; done?
+	dec c
+	jr nz, .repeatnext
+	dec b
+	jr z, .cleanup
+	
+.repeatnext
+	ld a, [hli]
+	ld [de], a
+	inc de
+	jr .repeat
+	
+	
+; a0 ; LZ_FLIP
+; repeat some decompressed data w/ flipped bit order
+.flip
+	dec c
+	jr nz, .flipnext
+	dec b
+	jp z, .cleanup
+	
+.flipnext
+	ld a, [hli]
+	push bc
+	ld bc, $0008
+	
+.fliploop
+	rra
+	rl b
+	dec c
+	jr nz, .fliploop
+	ld a, b
+	pop bc
+	ld [de], a
+	inc de
+	jr .flip
+	
+	
+; c0 ; LZ_REVERSE
+; repeat some decompressed data in reverse
+.reverse
+	dec c
+	jr nz, .reversenext
+	
+	dec b
+	jp z, .cleanup
+	
+.reversenext
+	ld a, [hld]
+	ld [de], a
+	inc de
+	jr .reverse
+	
+	
+.cleanup
+; get type of repeat we just used
+	pop hl
+; was it relative or absolute?
+	bit 7, [hl]
+	jr nz, .next
+
+; skip two bytes for absolute
+	inc hl
+; skip one byte for relative
+.next
+	inc hl
+	jp .loop
+; c2f
+
+
+
 
 UpdatePalsIfCGB: ; c2f
 ; update bgp data from BGPals
-- 
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