Add inventory.

src/item/inventory.h

@@ -0,0 +1,103 @@
+/**
+ * Copyright (c) 2026 Dominic Masters
+ * 
+ * This software is released under the MIT License.
+ * https://opensource.org/licenses/MIT
+ */
+
+#pragma once
+#include "item.h"
+
+#define ITEM_STACK_QUANTITY_MAX UINT8_MAX
+
+typedef struct {
+  itemid_t item;
+  uint8_t quantity;
+} inventorystack_t;
+
+typedef struct {
+  inventorystack_t *storage;
+  uint8_t storageSize;
+} inventory_t;
+
+/**
+ * Initializes an inventory.
+ * 
+ * @param inventory The inventory to initialize.
+ * @param storage The storage array for the inventory.
+ * @param storageSize The size of the storage array.
+ */
+void inventoryInit(
+  inventory_t* inventory,
+  inventorystack_t* storage,
+  uint8_t storageSize
+);
+
+/**
+ * Checks if a specific item exists in the inventory (and has quantity > 0).
+ * 
+ * @param inventory The inventory to check.
+ * @param item The item ID to check.
+ * @return true if the item exists, false otherwise.
+ */
+bool_t inventoryItemExists(const inventory_t *inventory, const itemid_t item);
+
+/**
+ * Sets the quantity of a specific item in the inventory.
+ * 
+ * @param inventory The inventory to modify.
+ * @param item The item ID to set.
+ * @param quantity The quantity to set.
+ */
+void inventorySet(
+  inventory_t *inventory,
+  const itemid_t item,
+  const uint8_t quantity
+);
+
+/**
+ * Adds a specific quantity of an item to the inventory.
+ * 
+ * @param inventory The inventory to modify.
+ * @param item The item ID to add.
+ * @param quantity The quantity to add.
+ */
+void inventoryAdd(
+  inventory_t *inventory,
+  const itemid_t item,
+  const uint8_t quantity
+);
+
+/**
+ * Removes an item from the inventory.
+ * 
+ * @param inventory The inventory to modify.
+ * @param item The item ID to remove.
+ */
+void inventoryRemove(inventory_t *inventory, const itemid_t item);
+
+/**
+ * Gets the count of a specific item in the inventory.
+ * 
+ * @param inventory The inventory to check.
+ * @param item The item ID to check.
+ * @return The count of the item in the inventory.
+ */
+uint8_t inventoryGetCount(const inventory_t *inventory, const itemid_t item);
+
+/**
+ * Checks if the inventory is full.
+ * 
+ * @param inventory The inventory to check.
+ * @return true if full, false otherwise.
+ */
+bool_t inventoryIsFull(const inventory_t *inventory);
+
+/**
+ * Checks if a specific item stack is full in the inventory.
+ * 
+ * @param inventory The inventory to check.
+ * @param item The item ID to check.
+ * @return true if the item stack is full, false otherwise.
+ */
+bool_t inventoryItemFull(const inventory_t *inventory, const itemid_t item);