VMM - get_page returns correct address

src/kernel/memory/vmm.c

@@ -0,0 +1,26 @@
+#include <memory.h>
+
+#define FLAGS_MASK (PAGE_SIZE-1)
+
+struct PT {
+  struct PT *p[ENTRIES_PER_PT];
+}__attribute__((packed));
+
+#define P(pt) ((struct PT *)((uintptr_t)pt & ~(FLAGS_MASK)))
+
+#define P3(pt, addr) (P(pt)->p[P4_OFFSET(addr)])
+#define P2(pt, addr) (P(P3(pt, addr))->p[P3_OFFSET(addr)])
+#define P1(pt, addr) (P(P2(pt, addr))->p[P2_OFFSET(addr)])
+#define P0(pt, addr) (P(P1(pt, addr))->p[P1_OFFSET(addr)])
+
+
+uintptr_t vmm_get_page(uintptr_t *P4, uintptr_t addr)
+{
+  if(P4
+      && P3(P4, addr)
+      && P2(P4, addr)
+      && P1(P4, addr)
+    )
+    return (uintptr_t)P0(P4, addr);
+  return 0;
+}