1 files changed, 83 insertions, 0 deletions
diff --git a/src/home/lcd.asm b/src/home/lcd.asm
new file mode 100644
index 0000000..5e8fc5d
--- /dev/null
+++ b/src/home/lcd.asm
@@ -0,0 +1,83 @@
+; wait for VBlankHandler to finish unless lcd is off
+WaitForVBlank:
+	push hl
+	ld a, [wLCDC]
+	bit LCDC_ENABLE_F, a
+	jr z, .lcd_off
+	ld hl, wVBlankCounter
+	ld a, [hl]
+.wait_vblank
+	halt
+	nop
+	cp [hl]
+	jr z, .wait_vblank
+.lcd_off
+	pop hl
+	ret
+
+; turn LCD on
+EnableLCD:
+	ld a, [wLCDC]        ;
+	bit LCDC_ENABLE_F, a ;
+	ret nz               ; assert that LCD is off
+	or LCDC_ON           ;
+	ld [wLCDC], a        ;
+	ldh [rLCDC], a       ; turn LCD on
+	ld a, FLUSH_ALL_PALS
+	ld [wFlushPaletteFlags], a
+	ret
+
+; wait for vblank, then turn LCD off
+DisableLCD:
+	ldh a, [rLCDC]       ;
+	bit LCDC_ENABLE_F, a ;
+	ret z                ; assert that LCD is on
+	ldh a, [rIE]
+	ld [wIE], a
+	res INT_VBLANK, a    ;
+	ldh [rIE], a         ; disable vblank interrupt
+.wait_vblank
+	ldh a, [rLY]         ;
+	cp LY_VBLANK         ;
+	jr nz, .wait_vblank  ; wait for vblank
+	ldh a, [rLCDC]       ;
+	and LCDC_OFF         ;
+	ldh [rLCDC], a       ;
+	ld a, [wLCDC]        ;
+	and LCDC_OFF         ;
+	ld [wLCDC], a        ; turn LCD off
+	xor a
+	ldh [rBGP], a
+	ldh [rOBP0], a
+	ldh [rOBP1], a
+	ld a, [wIE]
+	ldh [rIE], a
+	ret
+
+; set OBJ size: 8x8
+Set_OBJ_8x8:
+	ld a, [wLCDC]
+	and LCDC_OBJ8
+	ld [wLCDC], a
+	ret
+
+; set OBJ size: 8x16
+Set_OBJ_8x16:
+	ld a, [wLCDC]
+	or LCDC_OBJ16
+	ld [wLCDC], a
+	ret
+
+; set Window Display on
+Set_WD_on:
+	ld a, [wLCDC]
+	or LCDC_WINON
+	ld [wLCDC], a
+	ret
+
+; set Window Display off
+Set_WD_off:
+	ld a, [wLCDC]
+	and LCDC_WINOFF
+	ld [wLCDC], a
+	ret