First Commit

Upload literally everything from the pokecrystal16 expand-move-ID branch

engine/events/pokerus/apply_pokerus_tick.asm

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+ApplyPokerusTick:
+; decreases all pokemon's pokerus counter by b. if the lower nybble reaches zero, the pokerus is cured.
+	ld hl, wPartyMon1PokerusStatus ; wPartyMon1 + MON_PKRS
+	ld a, [wPartyCount]
+	and a
+	ret z ; make sure it's not wasting time on an empty party
+	ld c, a
+.loop
+	ld a, [hl]
+	and $f ; lower nybble is the number of days remaining
+	jr z, .next ; if already 0, skip
+	sub b ; subtract the number of days
+	jr nc, .ok ; max(result, 0)
+	xor a
+.ok
+	ld d, a ; back up this value because we need to preserve the strain (upper nybble)
+	ld a, [hl]
+	and $f0
+	add d
+	ld [hl], a ; this prevents a cured pokemon from recontracting pokerus
+.next
+	ld de, PARTYMON_STRUCT_LENGTH
+	add hl, de
+	dec c
+	jr nz, .loop
+	ret

engine/events/pokerus/check_pokerus.asm

@@ -0,0 +1,25 @@
+_CheckPokerus:
+; Return carry if a monster in your party has Pokerus
+
+; Get number of monsters to iterate over
+	ld a, [wPartyCount]
+	and a
+	jr z, .NoPokerus
+	ld b, a
+; Check each monster in the party for Pokerus
+	ld hl, wPartyMon1PokerusStatus
+	ld de, PARTYMON_STRUCT_LENGTH
+.Check:
+	ld a, [hl]
+	and $0f ; only the bottom nybble is used
+	jr nz, .HasPokerus
+; Next PartyMon
+	add hl, de
+	dec b
+	jr nz, .Check
+.NoPokerus:
+	and a
+	ret
+.HasPokerus:
+	scf
+	ret

engine/events/pokerus/pokerus.asm

@@ -0,0 +1,167 @@
+GivePokerusAndConvertBerries:
+	call ConvertBerriesToBerryJuice
+	ld hl, wPartyMon1PokerusStatus
+	ld a, [wPartyCount]
+	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, wStatusFlags2
+	bit STATUSFLAGS2_REACHED_GOLDENROD_F, [hl]
+	ret z
+	call Random
+	ldh a, [hRandomAdd]
+	and a
+	ret nz
+	ldh a, [hRandomSub]
+	cp 3
+	ret nc ; 3/65536 chance (00 00, 00 01 or 00 02)
+	ld a, [wPartyCount]
+	ld b, a
+.randomMonSelectLoop
+	call Random
+	and $7
+	cp b
+	jr nc, .randomMonSelectLoop
+	ld hl, wPartyMon1PokerusStatus
+	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 33 percent + 1
+	ret nc ; 1/3 chance
+
+	ld a, [wPartyCount]
+	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 50 percent + 1
+	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, [wPartyCount]
+	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
+
+ConvertBerriesToBerryJuice:
+; If we haven't been to Goldenrod City at least once,
+; prevent Shuckle from turning held Berry into Berry Juice.
+	ld hl, wStatusFlags2
+	bit STATUSFLAGS2_REACHED_GOLDENROD_F, [hl]
+	ret z
+	call Random
+	cp 1 out_of 16 ; 6.25% chance
+	ret nc
+	ld hl, SHUCKLE
+	call GetPokemonIDFromIndex
+	ld [wTempSpecies], a
+	ld hl, wPartyMons
+	ld a, [wPartyCount]
+.partyMonLoop
+	push af
+	push hl
+	ld a, [wTempSpecies]
+	cp [hl]
+	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
+.done
+	xor a
+	ld [wTempSpecies], a
+	ret
+
+.convertToJuice
+	ld a, BERRY_JUICE
+	ld [hl], a
+	pop hl
+	pop af
+	jr .done