Add GC

TODO: add pointer bitmaps

libsuicmez/suicmez_gc.h

@@ -0,0 +1,55 @@
+#ifndef SUICMEZ_GC_H
+#define SUICMEZ_GC_H
+
+#include <stdint.h>
+#include <stddef.h>
+
+#define YOUNG_SIZE       (1024 * 1024 * 2)
+#define SURVIVOR_SIZE    (512 * 1024)
+#define OLD_SIZE         (16 * 1024 * 1024)
+#define CARD_SIZE        512
+#define PROMOTION_AGE    2
+#define MAX_ROOTS        1024
+#define MARKED           0x1
+
+/* Forward declare Obj so ObjHeader can reference it */
+typedef struct Obj Obj;
+
+/* Header must come first */
+typedef struct ObjHeader {
+    uint32_t size;        // total object size incl header
+    uint16_t age;
+    uint16_t flags;
+    Obj *forwarding;      // non-NULL if moved
+} ObjHeader;
+
+/* Full object definition */
+struct Obj {
+    ObjHeader header;
+    void *fields[];
+};
+
+// --- API ---
+// Initialize the GC
+void gc_init(void);
+
+// Shutdown GC
+void gc_shutdown(void);
+
+// Allocate object in young generation
+void* gc_alloc_young(size_t size);
+
+// Root management
+void gc_add_root(void **ptr);
+void gc_remove_root(void **ptr);
+
+// Write barrier for old->young references
+void gc_write_barrier(void *src, void *dst);
+
+// Minor GC slice (incremental)
+void gc_minor_collect_slice(size_t max_objects);
+
+// Trigger major GC (async background)
+void gc_major_collect(void);
+
+#endif // SUICMEZ_GC_H