pokecrystal-board/engine/overworld/map_objects_2.asm

LoadObjectMasks:
	ld hl, wObjectMasks
	xor a
	ld bc, NUM_OBJECTS
	call ByteFill
	nop
	ld bc, wMapObjects
	ld de, wObjectMasks
	xor a
.loop
	push af
	push bc
	push de
	call GetObjectTimeMask
	jr c, .next
	call CheckObjectFlag
.next
	pop de
	ld [de], a
	inc de
	pop bc
	ld hl, MAPOBJECT_LENGTH
	add hl, bc
	ld b, h
	ld c, l
	pop af
	inc a
	cp NUM_OBJECTS
	jr nz, .loop
	ret

CheckObjectFlag:
	ld hl, MAPOBJECT_SPRITE
	add hl, bc
	ld a, [hl]
	and a
	jr z, .masked
	ld hl, MAPOBJECT_EVENT_FLAG
	add hl, bc
	ld a, [hli]
	ld e, a
	ld a, [hl]
	ld d, a
	cp HIGH(ALWAYS_SHOWN) ; HIGH(ALWAYS_HIDDEN)
	jr nz, .check
	ld a, e
	cp LOW(ALWAYS_SHOWN)
	jr z, .unmasked
	jr .masked
.check
	ld b, CHECK_FLAG
	call EventFlagAction
	ld a, c
	and a
	jr nz, .masked
.unmasked
	xor a
	ret

.masked
	ld a, -1
	scf
	ret

GetObjectTimeMask:
	call CheckObjectTime
	ld a, -1
	ret c
	xor a
	ret