DEF ITEM_ATTRF_NONE EQU 0
DEF ITEM_ATTRF_USABLE EQU (1 << 0)
DEF ITEM_ATTRF_WEAPON EQU (1 << 1)
DEF ITEM_ATTRF_ARMOR EQU (1 << 2)

DEF NEXT_ITEM_ID SET 1

; Declare a new item
; \1 Display name
; \2 Attributes
; \3 Sprite data filename
MACRO Item
    ASSERT STRLEN("\1") < 16

    ; Define item ID symbol
    DEF ID_NAME EQUS "\1_ID"
    DEF {ID_NAME} EQU NEXT_ITEM_ID
    EXPORT {ID_NAME}
    REDEF NEXT_ITEM_ID SET NEXT_ITEM_ID + 1

    DB \2

    ; Display name
    DB "\1"
    REPT 16 - STRLEN("\1")
        DB 0
    ENDR

    ; Sprite data
    INCBIN \3
ENDM

SECTION "Item Data", ROM0

; NOTE: Macro invocation MUST be indented in order to be expanded correctly
Items::
    Item COIN, ITEM_ATTRF_NONE, "png/sprite/item/coin.2bpp"