ref: 5ac4a517513da3acc80abdac0cc74f39b5f92907
dir: /engine/items/switch_items.asm/
SwitchItemsInBag: ld a, [wSwitchItem] and a jr z, .init ld b, a ld a, [wScrollingMenuCursorPosition] inc a cp b jr z, .trivial ld a, [wScrollingMenuCursorPosition] call ItemSwitch_GetNthItem ld a, [hl] cp -1 ret z ld a, [wSwitchItem] dec a ld [wSwitchItem], a call .try_combining_stacks jp c, .combine_stacks ld a, [wScrollingMenuCursorPosition] ld c, a ld a, [wSwitchItem] cp c jr c, .above jr .below .init: ld a, [wScrollingMenuCursorPosition] inc a ld [wSwitchItem], a ret .trivial: xor a ld [wSwitchItem], a ret .below: ld a, [wSwitchItem] call ItemSwitch_CopyItemToBuffer ld a, [wScrollingMenuCursorPosition] ld d, a ld a, [wSwitchItem] ld e, a call ItemSwitch_GetItemOffset push bc ld a, [wSwitchItem] call ItemSwitch_GetNthItem dec hl push hl call ItemSwitch_GetItemFormatSize add hl, bc ld d, h ld e, l pop hl pop bc call ItemSwitch_BackwardsCopyBytes ld a, [wScrollingMenuCursorPosition] call ItemSwitch_CopyBufferToItem xor a ld [wSwitchItem], a ret .above: ld a, [wSwitchItem] call ItemSwitch_CopyItemToBuffer ld a, [wScrollingMenuCursorPosition] ld d, a ld a, [wSwitchItem] ld e, a call ItemSwitch_GetItemOffset push bc ld a, [wSwitchItem] call ItemSwitch_GetNthItem ld d, h ld e, l call ItemSwitch_GetItemFormatSize add hl, bc pop bc call CopyBytes ld a, [wScrollingMenuCursorPosition] call ItemSwitch_CopyBufferToItem xor a ld [wSwitchItem], a ret .try_combining_stacks: ld a, [wSwitchItem] call ItemSwitch_GetNthItem ld d, h ld e, l ld a, [wScrollingMenuCursorPosition] call ItemSwitch_GetNthItem ld a, [de] cp [hl] jr nz, .no_combine ld a, [wScrollingMenuCursorPosition] call ItemSwitch_GetItemQuantity cp MAX_ITEM_STACK jr z, .no_combine ld a, [wSwitchItem] call ItemSwitch_GetItemQuantity cp MAX_ITEM_STACK jr nz, .combine .no_combine and a ret .combine scf ret .combine_stacks: ld a, [wSwitchItem] call ItemSwitch_GetNthItem inc hl push hl ld a, [wScrollingMenuCursorPosition] call ItemSwitch_GetNthItem inc hl ld a, [hl] pop hl add [hl] cp MAX_ITEM_STACK + 1 jr c, .merge_stacks sub MAX_ITEM_STACK push af ld a, [wScrollingMenuCursorPosition] call ItemSwitch_GetNthItem inc hl ld [hl], MAX_ITEM_STACK ld a, [wSwitchItem] call ItemSwitch_GetNthItem inc hl pop af ld [hl], a xor a ld [wSwitchItem], a ret .merge_stacks: push af ld a, [wScrollingMenuCursorPosition] call ItemSwitch_GetNthItem inc hl pop af ld [hl], a ld hl, wMenuData_ItemsPointerAddr ld a, [hli] ld h, [hl] ld l, a ld a, [wSwitchItem] cp [hl] jr nz, .not_combining_last_item dec [hl] ld a, [wSwitchItem] call ItemSwitch_GetNthItem ld [hl], -1 ; end xor a ld [wSwitchItem], a ret .not_combining_last_item: dec [hl] call ItemSwitch_GetItemFormatSize push bc ld a, [wSwitchItem] call ItemSwitch_GetNthItem pop bc push hl add hl, bc pop de .copy_loop ld a, [hli] ld [de], a inc de cp -1 ; end? jr nz, .copy_loop xor a ld [wSwitchItem], a ret ItemSwitch_CopyItemToBuffer: call ItemSwitch_GetNthItem ld de, wSwitchItemBuffer call ItemSwitch_GetItemFormatSize call CopyBytes ret ItemSwitch_CopyBufferToItem: call ItemSwitch_GetNthItem ld d, h ld e, l ld hl, wSwitchItemBuffer call ItemSwitch_GetItemFormatSize call CopyBytes ret ItemSwitch_GetNthItem: push af call ItemSwitch_GetItemFormatSize ld hl, wMenuData_ItemsPointerAddr ld a, [hli] ld h, [hl] ld l, a inc hl pop af call AddNTimes ret ItemSwitch_GetItemOffset: push hl call ItemSwitch_GetItemFormatSize ld a, d sub e jr nc, .dont_negate dec a cpl .dont_negate ld hl, 0 call AddNTimes ld b, h ld c, l pop hl ret ItemSwitch_GetItemFormatSize: push hl ld a, [wMenuData_ScrollingMenuItemFormat] ld c, a ld b, 0 ld hl, .item_format_sizes add hl, bc add hl, bc ld c, [hl] inc hl ld b, [hl] pop hl ret .item_format_sizes: ; entries correspond to SCROLLINGMENU_ITEMS_* constants dw 0 ; unused dw 1 ; SCROLLINGMENU_ITEMS_NORMAL dw 2 ; SCROLLINGMENU_ITEMS_QUANTITY ItemSwitch_GetItemQuantity: push af call ItemSwitch_GetItemFormatSize ld a, c cp 2 jr nz, .no_quantity pop af call ItemSwitch_GetNthItem inc hl ld a, [hl] ret .no_quantity pop af ld a, 1 ret ItemSwitch_BackwardsCopyBytes: .loop ld a, [hld] ld [de], a dec de dec bc ld a, b or c jr nz, .loop ret