kernel: implement object handle tables

include/mango/handle.h

@@ -0,0 +1,56 @@
+#ifndef MANGO_HANDLE_H_
+#define MANGO_HANDLE_H_
+
+#include <mango/bitmap.h>
+#include <mango/status.h>
+#include <stdint.h>
+
+/* subtract 32 bytes to account for the handle bitmap */
+#define HANDLES_PER_TABLE ((4096 - 32) / sizeof(struct handle))
+#define REFS_PER_TABLE    ((4096 - 64) / sizeof(struct handle_table *))
+
+typedef uint32_t kern_handle_t;
+
+struct object;
+
+struct handle {
+	union {
+		struct object *h_object;
+		uint64_t __x;
+	};
+
+	uint64_t h_flags;
+};
+
+struct handle_table {
+	union {
+		struct {
+			/* bitmap tracks which bits in t_handle_list are
+			 * allocated */
+			DECLARE_BITMAP(t_handle_map, HANDLES_PER_TABLE);
+			struct handle t_handle_list[HANDLES_PER_TABLE];
+		} t_handles;
+
+		struct {
+			/* bitmap tracks which sub-tables are fully-allocated */
+			DECLARE_BITMAP(t_subtable_map, REFS_PER_TABLE);
+			struct handle_table *t_subtable_list[REFS_PER_TABLE];
+		} t_subtables;
+	};
+};
+
+extern struct handle_table *handle_table_create(void);
+extern void handle_table_destroy(struct handle_table *tab);
+
+extern kern_status_t handle_table_alloc_handle(
+	struct handle_table *tab,
+	struct handle **out_slot,
+	kern_handle_t *out_handle);
+extern void handle_table_free_handle(
+	struct handle_table *tab,
+	kern_handle_t handle);
+extern struct handle *handle_table_get_handle(
+	struct handle_table *tab,
+	kern_handle_t handle);
+
+#endif