1 files changed, 225 insertions, 0 deletions
diff --git a/engine/init.asm b/engine/init.asm
new file mode 100644
index 000000000..d7594ae1d
--- /dev/null
+++ b/engine/init.asm
@@ -0,0 +1,225 @@
+Reset: ; 150
+	di
+	call CleanSoundRestart
+	xor a
+	ld [$ffde], a
+	call ClearPalettes
+	xor a
+	ld [rIF], a
+	ld a, 1 ; VBlank int
+	ld [rIE], a
+	ei
+
+	ld hl, $cfbe
+	set 7, [hl]
+
+	ld c, 32
+	call DelayFrames
+
+	jr Init
+; 16e
+
+
+_Start: ; 16e
+	cp $11
+	jr z, .asm_175
+	xor a
+	jr .asm_177
+
+.asm_175
+	ld a, $1
+
+.asm_177
+	ld [hCGB], a
+	ld a, $1
+	ld [$ffea], a
+; 17d
+
+
+Init: ; 17d
+
+	di
+
+	xor a
+	ld [rIF], a
+	ld [rIE], a
+	ld [rRP], a
+	ld [rSCX], a
+	ld [rSCY], a
+	ld [rSB], a
+	ld [rSC], a
+	ld [rWX], a
+	ld [rWY], a
+	ld [rBGP], a
+	ld [rOBP0], a
+	ld [rOBP1], a
+	ld [rTMA], a
+	ld [rTAC], a
+	ld [$d000], a
+
+	ld a, %100 ; Start timer at 4096Hz
+	ld [rTAC], a
+
+.wait
+	ld a, [rLY]
+	cp 145
+	jr nz, .wait
+
+	xor a
+	ld [rLCDC], a
+
+; Clear WRAM bank 0
+	ld hl, $c000
+	ld bc, $d000 - $c000
+.asm_1b1
+	ld [hl], 0
+	inc hl
+	dec bc
+	ld a, b
+	or c
+	jr nz, .asm_1b1
+
+	ld sp, Stack - 1
+
+; Clear HRAM
+	ld a, [hCGB]
+	push af
+	ld a, [$ffea]
+	push af
+	xor a
+	ld hl, $ff80
+	ld bc, $ffff - $ff80
+	call ByteFill
+	pop af
+	ld [$ffea], a
+	pop af
+	ld [hCGB], a
+
+	call ClearWRAM
+	ld a, 1
+	ld [rSVBK], a
+	call ClearVRAM
+	call ClearSprites
+	call Function270
+
+
+	ld a, BANK(LoadPushOAM)
+	rst Bankswitch
+
+	call LoadPushOAM
+
+	xor a
+	ld [$ffde], a
+	ld [hSCX], a
+	ld [hSCY], a
+	ld [rJOYP], a
+
+	ld a, $8 ; HBlank int enable
+	ld [rSTAT], a
+
+	ld a, $90
+	ld [hWY], a
+	ld [rWY], a
+
+	ld a, 7
+	ld [hWX], a
+	ld [rWX], a
+
+	ld a, %11100011
+	; LCD on
+	; Win tilemap 1
+	; Win on
+	; BG/Win tiledata 0
+	; BG Tilemap 0
+	; OBJ 8x8
+	; OBJ on
+	; BG on
+	ld [rLCDC], a
+
+	ld a, $ff
+	ld [$ffcb], a
+
+	callba Function9890
+
+	ld a, $9c
+	ld [$ffd7], a
+
+	xor a
+	ld [hBGMapAddress], a
+
+	callba StartClock
+
+	xor a
+	ld [MBC3LatchClock], a
+	ld [MBC3SRamEnable], a
+
+	ld a, [hCGB]
+	and a
+	jr z, .asm_22b
+	call Function2ff7
+.asm_22b
+
+	xor a
+	ld [rIF], a
+	ld a, %1111 ; VBlank, LCDStat, Timer, Serial interrupts
+	ld [rIE], a
+	ei
+
+	call DelayFrame
+
+	ld a, $30
+	call Predef
+
+	call CleanSoundRestart
+	xor a
+	ld [CurMusic], a
+	jp GameInit
+; 245
+
+
+ClearVRAM: ; 245
+; Wipe VRAM banks 0 and 1
+
+	ld a, 1
+	ld [rVBK], a
+	call .clear
+
+	xor a
+	ld [rVBK], a
+.clear
+	ld hl, VTiles0
+	ld bc, $2000
+	xor a
+	call ByteFill
+	ret
+; 25a
+
+ClearWRAM: ; 25a
+; Wipe swappable WRAM banks (1-7)
+
+	ld a, 1
+.asm_25c
+	push af
+	ld [rSVBK], a
+	xor a
+	ld hl, $d000
+	ld bc, $1000
+	call ByteFill
+	pop af
+	inc a
+	cp 8
+	jr nc, .asm_25c
+	ret
+; 270
+
+Function270: ; 270
+	ld a, $0
+	call GetSRAMBank
+	ld hl, $a000
+	ld bc, $0020
+	xor a
+	call ByteFill
+	call CloseSRAM
+	ret
+; 283
+