Move events/ to engine/events/

engine/events/pokerus/pokerus.asm

@@ -0,0 +1,160 @@
+GivePokerusAndConvertBerries: ; 2ed44
+	call ConvertBerriesToBerryJuice
+	ld hl, PartyMon1PokerusStatus
+	ld a, [PartyCount]
+	ld b, a
+	ld de, PARTYMON_STRUCT_LENGTH
+; Check to see if any of your Pokemon already has Pokerus.
+; If so, sample its spread through your party.
+; This means that you cannot get Pokerus de novo while
+; a party member has an active infection.
+.loopMons
+	ld a, [hl]
+	and $f
+	jr nz, .TrySpreadPokerus
+	add hl, de
+	dec b
+	jr nz, .loopMons
+
+; If we haven't been to Goldenrod City at least once,
+; prevent the contraction of Pokerus.
+	ld hl, StatusFlags2
+	bit 6, [hl]
+	ret z
+	call Random
+	ld a, [hRandomAdd]
+	and a
+	ret nz
+	ld a, [hRandomSub]
+	cp $3
+	ret nc                 ; 3/65536 chance (00 00, 00 01 or 00 02)
+	ld a, [PartyCount]
+	ld b, a
+.randomMonSelectLoop
+	call Random
+	and $7
+	cp b
+	jr nc, .randomMonSelectLoop
+	ld hl, PartyMon1PokerusStatus
+	call GetPartyLocation  ; get pokerus byte of random mon
+	ld a, [hl]
+	and $f0
+	ret nz                 ; if it already has pokerus, do nothing
+.randomPokerusLoop         ; Simultaneously sample the strain and duration
+	call Random
+	and a
+	jr z, .randomPokerusLoop
+	ld b, a
+	and $f0
+	jr z, .load_pkrs
+	ld a, b
+	and $7
+	inc a
+.load_pkrs
+	ld b, a ; this should come before the label
+	swap b
+	and $3
+	inc a
+	add b
+	ld [hl], a
+	ret
+
+.TrySpreadPokerus:
+	call Random
+	cp 1 + 33 percent
+	ret nc              ; 1/3 chance
+
+	ld a, [PartyCount]
+	cp 1
+	ret z               ; only one mon, nothing to do
+
+	ld c, [hl]
+	ld a, b
+	cp 2
+	jr c, .checkPreviousMonsLoop    ; no more mons after this one, go backwards
+
+	call Random
+	cp 1 + 50 percent
+	jr c, .checkPreviousMonsLoop    ; 1/2 chance, go backwards
+.checkFollowingMonsLoop
+	add hl, de
+	ld a, [hl]
+	and a
+	jr z, .infectMon
+	ld c, a
+	and $3
+	ret z               ; if mon has cured pokerus, stop searching
+	dec b               ; go on to next mon
+	ld a, b
+	cp 1
+	jr nz, .checkFollowingMonsLoop ; no more mons left
+	ret
+
+.checkPreviousMonsLoop
+	ld a, [PartyCount]
+	cp b
+	ret z               ; no more mons
+	ld a, l
+	sub e
+	ld l, a
+	ld a, h
+	sbc d
+	ld h, a
+	ld a, [hl]
+	and a
+	jr z, .infectMon
+	ld c, a
+	and $3
+	ret z               ; if mon has cured pokerus, stop searching
+	inc b               ; go on to next mon
+	jr .checkPreviousMonsLoop
+
+.infectMon
+	ld a, c
+	and $f0
+	ld b, a
+	ld a, c
+	swap a
+	and $3
+	inc a
+	add b
+	ld [hl], a
+	ret
+
+; any berry held by a Shuckle may be converted to berry juice
+ConvertBerriesToBerryJuice: ; 2ede6
+	ld hl, StatusFlags2
+	bit 6, [hl]
+	ret z
+	call Random
+	cp $10
+	ret nc              ; 1/16 chance
+	ld hl, PartyMons
+	ld a, [PartyCount]
+.partyMonLoop
+	push af
+	push hl
+	ld a, [hl]
+	cp SHUCKLE
+	jr nz, .loopMon
+	ld bc, MON_ITEM
+	add hl, bc
+	ld a, [hl]
+	cp BERRY
+	jr z, .convertToJuice
+
+.loopMon
+	pop hl
+	ld bc, PARTYMON_STRUCT_LENGTH
+	add hl, bc
+	pop af
+	dec a
+	jr nz, .partyMonLoop
+	ret
+
+.convertToJuice
+	ld a, BERRY_JUICE
+	ld [hl], a
+	pop hl
+	pop af
+	ret