Add shop shield handling, credits counter, softlock protection

multiworld.asm

@@ -89,6 +89,9 @@ GetMultiworldItem:
 	PHP
 	LDA.l !MULTIWORLD_ITEM : BNE +
 	LDA.l !MULTIWORLD_HUD_TIMER : BNE +
+	LDA.l ShieldEquipment : BNE ++
+	LDA.l PikitItem : CMP.b #$04 : BNE +
+	++
 		BRL .return
 	+
 
@@ -123,6 +126,34 @@ GetMultiworldItem:
 		BRL .return
 	+
 
+	LDA.l ShieldEquipment : BNE +
+	LDA.l PikitItem : CMP.b #$04 : BEQ +
+
+	LDY.b #$10
+	-
+		DEY
+		BMI .restore_shield
+		LDA.w $0E20, Y
+		CMP.b #$AA
+		BNE - ; go to next sprite if this sprite isn't a pikit
+		LDA.w $0DD0, Y
+		BEQ - ; go to next sprite if this sprite is dead/inactive
+		LDA.w $0ED0, Y
+		CMP.b #$04
+		BNE - ; go to next sprite if this pikit isn't grabbing a shield
+		LDA.w $0E90, Y
+		CMP.b #$04
+		BNE - ; go to next sprite if this pikit isn't grabbing a shield
+
+		BRA + ; active pikit has a shield
+
+	.restore_shield
+		; we have a pikit item, but no shield, and there's no pikit actively
+		; eating a shield, so return the shield to prevent a softlock
+		LDA.b #$01
+		STA.l ShieldEquipment
+	+
+
 	LDA.l !MULTIWORLD_ITEM : BNE +
 		BRL .return
 	+