Declare items with macros

src/item.s

@@ -0,0 +1,29 @@
+DEF NEXT_ITEM_ID SET 1
+
+; Declare a new item
+; \1 Display name
+; \2 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
+
+    ; Display name
+    DB "\1"
+    REPT 16 - STRLEN("\1")
+        DB 0
+    ENDR
+
+    ; Sprite data
+    INCBIN \2
+ENDM
+
+SECTION "Item Data", ROM0
+
+; NOTE: Macro invocation MUST be indented in order to be expanded correctly
+Items::
+    Item COIN, "png/sprite/item/coin.2bpp"