1 files changed, 581 insertions, 0 deletions
diff --git a/engine/items/items.asm b/engine/items/items.asm
new file mode 100644
index 000000000..c07042aed
--- /dev/null
+++ b/engine/items/items.asm
@@ -0,0 +1,581 @@
+_ReceiveItem:: ; d1d5
+	call DoesHLEqualNumItems
+	jp nz, PutItemInPocket
+	push hl
+	call CheckItemPocket
+	pop de
+	ld a, [wItemAttributeParamBuffer]
+	dec a
+	ld hl, .Pockets
+	rst JumpTable
+	ret
+
+.Pockets: ; d1e9
+; entries correspond to item types
+	dw .Item
+	dw .KeyItem
+	dw .Ball
+	dw .TMHM
+
+.Item: ; d1f1
+	ld h, d
+	ld l, e
+	jp PutItemInPocket
+
+.KeyItem: ; d1f6
+	ld h, d
+	ld l, e
+	jp ReceiveKeyItem
+
+.Ball: ; d1fb
+	ld hl, wNumBalls
+	jp PutItemInPocket
+
+.TMHM: ; d201
+	ld h, d
+	ld l, e
+	ld a, [wCurItem]
+	ld c, a
+	call GetTMHMNumber
+	jp ReceiveTMHM
+
+_TossItem:: ; d20d
+	call DoesHLEqualNumItems
+	jr nz, .remove
+	push hl
+	call CheckItemPocket
+	pop de
+	ld a, [wItemAttributeParamBuffer]
+	dec a
+	ld hl, .Pockets
+	rst JumpTable
+	ret
+
+.Pockets:
+; entries correspond to item types
+	dw .Item
+	dw .KeyItem
+	dw .Ball
+	dw .TMHM
+
+.Ball: ; d228
+	ld hl, wNumBalls
+	jp RemoveItemFromPocket
+
+.TMHM: ; d22e
+	ld h, d
+	ld l, e
+	ld a, [wCurItem]
+	ld c, a
+	call GetTMHMNumber
+	jp TossTMHM
+
+.KeyItem: ; d23a
+	ld h, d
+	ld l, e
+	jp TossKeyItem
+
+.Item: ; d23f
+	ld h, d
+	ld l, e
+
+.remove
+	jp RemoveItemFromPocket
+
+_CheckItem:: ; d244
+	call DoesHLEqualNumItems
+	jr nz, .nope
+	push hl
+	call CheckItemPocket
+	pop de
+	ld a, [wItemAttributeParamBuffer]
+	dec a
+	ld hl, .Pockets
+	rst JumpTable
+	ret
+
+.Pockets:
+; entries correspond to item types
+	dw .Item
+	dw .KeyItem
+	dw .Ball
+	dw .TMHM
+
+.Ball: ; d25f
+	ld hl, wNumBalls
+	jp CheckTheItem
+
+.TMHM: ; d265
+	ld h, d
+	ld l, e
+	ld a, [wCurItem]
+	ld c, a
+	call GetTMHMNumber
+	jp CheckTMHM
+
+.KeyItem: ; d271
+	ld h, d
+	ld l, e
+	jp CheckKeyItems
+
+.Item: ; d276
+	ld h, d
+	ld l, e
+
+.nope
+	jp CheckTheItem
+
+DoesHLEqualNumItems: ; d27b
+	ld a, l
+	cp LOW(wNumItems)
+	ret nz
+	ld a, h
+	cp HIGH(wNumItems)
+	ret
+
+GetPocketCapacity: ; d283
+	ld c, MAX_ITEMS
+	ld a, e
+	cp LOW(wNumItems)
+	jr nz, .not_bag
+	ld a, d
+	cp HIGH(wNumItems)
+	ret z
+
+.not_bag
+	ld c, MAX_PC_ITEMS
+	ld a, e
+	cp LOW(wPCItems)
+	jr nz, .not_pc
+	ld a, d
+	cp HIGH(wPCItems)
+	ret z
+
+.not_pc
+	ld c, MAX_BALLS
+	ret
+
+PutItemInPocket: ; d29c
+	ld d, h
+	ld e, l
+	inc hl
+	ld a, [wCurItem]
+	ld c, a
+	ld b, 0
+.loop
+	ld a, [hli]
+	cp -1
+	jr z, .terminator
+	cp c
+	jr nz, .next
+	ld a, 99
+	sub [hl]
+	add b
+	ld b, a
+	ld a, [wItemQuantityChangeBuffer]
+	cp b
+	jr z, .ok
+	jr c, .ok
+
+.next
+	inc hl
+	jr .loop
+
+.terminator
+	call GetPocketCapacity
+	ld a, [de]
+	cp c
+	jr c, .ok
+	and a
+	ret
+
+.ok
+	ld h, d
+	ld l, e
+	ld a, [wCurItem]
+	ld c, a
+	ld a, [wItemQuantityChangeBuffer]
+	ld [wItemQuantityBuffer], a
+.loop2
+	inc hl
+	ld a, [hli]
+	cp -1
+	jr z, .terminator2
+	cp c
+	jr nz, .loop2
+	ld a, [wItemQuantityBuffer]
+	add [hl]
+	cp 100
+	jr nc, .newstack
+	ld [hl], a
+	jr .done
+
+.newstack
+	ld [hl], 99
+	sub 99
+	ld [wItemQuantityBuffer], a
+	jr .loop2
+
+.terminator2
+	dec hl
+	ld a, [wCurItem]
+	ld [hli], a
+	ld a, [wItemQuantityBuffer]
+	ld [hli], a
+	ld [hl], -1
+	ld h, d
+	ld l, e
+	inc [hl]
+
+.done
+	scf
+	ret
+
+RemoveItemFromPocket: ; d2ff
+	ld d, h
+	ld e, l
+	ld a, [hli]
+	ld c, a
+	ld a, [wCurItemQuantity]
+	cp c
+	jr nc, .ok ; memory
+	ld c, a
+	ld b, $0
+	add hl, bc
+	add hl, bc
+	ld a, [wCurItem]
+	cp [hl]
+	inc hl
+	jr z, .skip
+	ld h, d
+	ld l, e
+	inc hl
+
+.ok
+	ld a, [wCurItem]
+	ld b, a
+.loop
+	ld a, [hli]
+	cp b
+	jr z, .skip
+	cp -1
+	jr z, .nope
+	inc hl
+	jr .loop
+
+.skip
+	ld a, [wItemQuantityChangeBuffer]
+	ld b, a
+	ld a, [hl]
+	sub b
+	jr c, .nope
+	ld [hl], a
+	ld [wItemQuantityBuffer], a
+	and a
+	jr nz, .yup
+	dec hl
+	ld b, h
+	ld c, l
+	inc hl
+	inc hl
+.loop2
+	ld a, [hli]
+	ld [bc], a
+	inc bc
+	cp -1
+	jr nz, .loop2
+	ld h, d
+	ld l, e
+	dec [hl]
+
+.yup
+	scf
+	ret
+
+.nope
+	and a
+	ret
+
+CheckTheItem: ; d349
+	ld a, [wCurItem]
+	ld c, a
+.loop
+	inc hl
+	ld a, [hli]
+	cp -1
+	jr z, .done
+	cp c
+	jr nz, .loop
+	scf
+	ret
+
+.done
+	and a
+	ret
+
+ReceiveKeyItem: ; d35a
+	ld hl, wNumKeyItems
+	ld a, [hli]
+	cp MAX_KEY_ITEMS
+	jr nc, .nope
+	ld c, a
+	ld b, 0
+	add hl, bc
+	ld a, [wCurItem]
+	ld [hli], a
+	ld [hl], -1
+	ld hl, wNumKeyItems
+	inc [hl]
+	scf
+	ret
+
+.nope
+	and a
+	ret
+
+TossKeyItem: ; d374
+	ld a, [wCurItemQuantity]
+	ld e, a
+	ld d, 0
+	ld hl, wNumKeyItems
+	ld a, [hl]
+	cp e
+	jr nc, .ok
+	call .Toss
+	ret nc
+	jr .ok2
+
+.ok
+	dec [hl]
+	inc hl
+	add hl, de
+
+.ok2
+	ld d, h
+	ld e, l
+	inc hl
+.loop
+	ld a, [hli]
+	ld [de], a
+	inc de
+	cp -1
+	jr nz, .loop
+	scf
+	ret
+
+.Toss: ; d396
+	ld hl, wNumKeyItems
+	ld a, [wCurItem]
+	ld c, a
+.loop3
+	inc hl
+	ld a, [hl]
+	cp c
+	jr z, .ok3
+	cp -1
+	jr nz, .loop3
+	xor a
+	ret
+
+.ok3
+	ld a, [wNumKeyItems]
+	dec a
+	ld [wNumKeyItems], a
+	scf
+	ret
+
+CheckKeyItems: ; d3b1
+	ld a, [wCurItem]
+	ld c, a
+	ld hl, wKeyItems
+.loop
+	ld a, [hli]
+	cp c
+	jr z, .done
+	cp -1
+	jr nz, .loop
+	and a
+	ret
+
+.done
+	scf
+	ret
+
+ReceiveTMHM: ; d3c4
+	dec c
+	ld b, 0
+	ld hl, wTMsHMs
+	add hl, bc
+	ld a, [wItemQuantityChangeBuffer]
+	add [hl]
+	cp 100
+	jr nc, .toomany
+	ld [hl], a
+	scf
+	ret
+
+.toomany
+	and a
+	ret
+
+TossTMHM: ; d3d8
+	dec c
+	ld b, 0
+	ld hl, wTMsHMs
+	add hl, bc
+	ld a, [wItemQuantityChangeBuffer]
+	ld b, a
+	ld a, [hl]
+	sub b
+	jr c, .nope
+	ld [hl], a
+	ld [wItemQuantityBuffer], a
+	jr nz, .yup
+	ld a, [wTMHMPocketScrollPosition]
+	and a
+	jr z, .yup
+	dec a
+	ld [wTMHMPocketScrollPosition], a
+
+.yup
+	scf
+	ret
+
+.nope
+	and a
+	ret
+
+CheckTMHM: ; d3fb
+	dec c
+	ld b, $0
+	ld hl, wTMsHMs
+	add hl, bc
+	ld a, [hl]
+	and a
+	ret z
+	scf
+	ret
+
+GetTMHMNumber:: ; d407
+; Return the number of a TM/HM by item id c.
+	ld a, c
+; Skip any dummy items.
+	cp ITEM_C3 ; TM04-05
+	jr c, .done
+	cp ITEM_DC ; TM28-29
+	jr c, .skip
+	dec a
+.skip
+	dec a
+.done
+	sub TM01
+	inc a
+	ld c, a
+	ret
+
+GetNumberedTMHM: ; d417
+; Return the item id of a TM/HM by number c.
+	ld a, c
+; Skip any gaps.
+	cp ITEM_C3 - (TM01 - 1)
+	jr c, .done
+	cp ITEM_DC - (TM01 - 1) - 1
+	jr c, .skip_one
+.skip_two
+	inc a
+.skip_one
+	inc a
+.done
+	add TM01
+	dec a
+	ld c, a
+	ret
+
+_CheckTossableItem:: ; d427
+; Return 1 in wItemAttributeParamBuffer and carry if wCurItem can't be removed from the bag.
+	ld a, ITEMATTR_PERMISSIONS
+	call GetItemAttr
+	bit CANT_TOSS_F, a
+	jr nz, ItemAttr_ReturnCarry
+	and a
+	ret
+
+CheckSelectableItem: ; d432
+; Return 1 in wItemAttributeParamBuffer and carry if wCurItem can't be selected.
+	ld a, ITEMATTR_PERMISSIONS
+	call GetItemAttr
+	bit CANT_SELECT_F, a
+	jr nz, ItemAttr_ReturnCarry
+	and a
+	ret
+
+CheckItemPocket:: ; d43d
+; Return the pocket for wCurItem in wItemAttributeParamBuffer.
+	ld a, ITEMATTR_POCKET
+	call GetItemAttr
+	and $f
+	ld [wItemAttributeParamBuffer], a
+	ret
+
+CheckItemContext: ; d448
+; Return the context for wCurItem in wItemAttributeParamBuffer.
+	ld a, ITEMATTR_HELP
+	call GetItemAttr
+	and $f
+	ld [wItemAttributeParamBuffer], a
+	ret
+
+CheckItemMenu: ; d453
+; Return the menu for wCurItem in wItemAttributeParamBuffer.
+	ld a, ITEMATTR_HELP
+	call GetItemAttr
+	swap a
+	and $f
+	ld [wItemAttributeParamBuffer], a
+	ret
+
+GetItemAttr: ; d460
+; Get attribute a of wCurItem.
+
+	push hl
+	push bc
+
+	ld hl, ItemAttributes
+	ld c, a
+	ld b, 0
+	add hl, bc
+
+	xor a
+	ld [wItemAttributeParamBuffer], a
+
+	ld a, [wCurItem]
+	dec a
+	ld c, a
+	ld a, ITEMATTR_STRUCT_LENGTH
+	call AddNTimes
+	ld a, BANK(ItemAttributes)
+	call GetFarByte
+
+	pop bc
+	pop hl
+	ret
+
+ItemAttr_ReturnCarry: ; d47f
+	ld a, 1
+	ld [wItemAttributeParamBuffer], a
+	scf
+	ret
+
+GetItemPrice: ; d486
+; Return the price of wCurItem in de.
+	push hl
+	push bc
+	ld a, ITEMATTR_PRICE
+	call GetItemAttr
+	ld e, a
+	ld a, ITEMATTR_PRICE_HI
+	call GetItemAttr
+	ld d, a
+	pop bc
+	pop hl
+	ret