1 files changed, 158 insertions, 0 deletions
diff --git a/src/home/setup.asm b/src/home/setup.asm
new file mode 100644
index 0000000..bf58452
--- /dev/null
+++ b/src/home/setup.asm
@@ -0,0 +1,158 @@
+; initialize scroll, window, and lcdc registers, set trampoline functions
+; for the lcdc and vblank interrupts, latch clock data, and enable SRAM/RTC
+SetupRegisters: ; 030b (0:030b)
+	xor a
+	ldh [rSCY], a
+	ldh [rSCX], a
+	ldh [rWY], a
+	ldh [rWX], a
+	ld [wcab0], a
+	ld [wcab1], a
+	ld [wcab2], a
+	ldh [hSCX], a
+	ldh [hSCY], a
+	ldh [hWX], a
+	ldh [hWY], a
+	xor a
+	ld [wReentrancyFlag], a
+	ld a, $c3            ; $c3 = jp nn
+	ld [wLCDCFunctionTrampoline], a
+	ld [wVBlankFunctionTrampoline], a
+	ld hl, wVBlankFunctionTrampoline + 1
+	ld [hl], LOW(NoOp)   ;
+	inc hl               ; load `jp NoOp`
+	ld [hl], HIGH(NoOp)  ;
+	ld a, LCDC_BGON | LCDC_OBJON | LCDC_OBJ16 | LCDC_WIN9C00
+	ld [wLCDC], a
+	ld a, $1
+	ld [MBC3LatchClock], a
+	ld a, SRAM_ENABLE
+	ld [MBC3SRamEnable], a
+NoOp: ; 0348 (0:0348)
+	ret
+
+; sets wConsole and, if CGB, selects WRAM bank 1 and switches to double speed mode
+DetectConsole: ; 0349 (0:0349)
+	ld b, CONSOLE_CGB
+	cp GBC
+	jr z, .got_console
+	call DetectSGB
+	ld b, CONSOLE_DMG
+	jr nc, .got_console
+	call InitSGB
+	ld b, CONSOLE_SGB
+.got_console
+	ld a, b
+	ld [wConsole], a
+	cp CONSOLE_CGB
+	ret nz
+	ld a, $01
+	ldh [rSVBK], a
+	call SwitchToCGBDoubleSpeed
+	ret
+
+; initialize the palettes (both monochrome and color)
+SetupPalettes: ; 036a (0:036a)
+	ld hl, wBGP
+	ld a, %11100100
+	ldh [rBGP], a
+	ld [hli], a ; wBGP
+	ldh [rOBP0], a
+	ldh [rOBP1], a
+	ld [hli], a ; wOBP0
+	ld [hl], a ; wOBP1
+	xor a
+	ld [wFlushPaletteFlags], a
+	ld a, [wConsole]
+	cp CONSOLE_CGB
+	ret nz
+	ld de, wBackgroundPalettesCGB
+	ld c, 16
+.copy_pals_loop
+	ld hl, InitialPalette
+	ld b, CGB_PAL_SIZE
+.copy_bytes_loop
+	ld a, [hli]
+	ld [de], a
+	inc de
+	dec b
+	jr nz, .copy_bytes_loop
+	dec c
+	jr nz, .copy_pals_loop
+	call FlushAllCGBPalettes
+	ret
+
+InitialPalette: ; 0399 (0:0399)
+	rgb 28, 28, 24
+	rgb 21, 21, 16
+	rgb 10, 10, 08
+	rgb 00, 00, 00
+
+; clear VRAM tile data ([wTileMapFill] should be an empty tile)
+SetupVRAM: ; 03a1 (0:03a1)
+	call FillTileMap
+	call CheckForCGB
+	jr c, .vram0
+	call BankswitchVRAM1
+	call .vram0
+	call BankswitchVRAM0
+.vram0
+	ld hl, v0Tiles0
+	ld bc, v0BGMap0 - v0Tiles0
+.loop
+	xor a
+	ld [hli], a
+	dec bc
+	ld a, b
+	or c
+	jr nz, .loop
+	ret
+
+; fill VRAM0 BG map 0 with [wTileMapFill] and VRAM1 BG map 0 with $00
+FillTileMap: ; 03c0 (0:03c0)
+	call BankswitchVRAM0
+	ld hl, v0BGMap0
+	ld bc, v0BGMap1 - v0BGMap0
+.vram0_loop
+	ld a, [wTileMapFill]
+	ld [hli], a
+	dec bc
+	ld a, c
+	or b
+	jr nz, .vram0_loop
+	ld a, [wConsole]
+	cp CONSOLE_CGB
+	ret nz
+	call BankswitchVRAM1
+	ld hl, v1BGMap0
+	ld bc, v1BGMap1 - v1BGMap0
+.vram1_loop
+	xor a
+	ld [hli], a
+	dec bc
+	ld a, c
+	or b
+	jr nz, .vram1_loop
+	call BankswitchVRAM0
+	ret
+
+; zero work RAM, stack area, and high RAM ($C000-$DFFF, $FF80-$FFEF)
+ZeroRAM: ; 03ec (0:03ec)
+	ld hl, $c000
+	ld bc, $e000 - $c000
+.zero_wram_loop
+	xor a
+	ld [hli], a
+	dec bc
+	ld a, c
+	or b
+	jr nz, .zero_wram_loop
+	ld c, LOW($ff80)
+	ld b, $fff0 - $ff80
+	xor a
+.zero_hram_loop
+	ld [$ff00+c], a
+	inc c
+	dec b
+	jr nz, .zero_hram_loop
+	ret