Add PAGE_SIZE constant

src/hulk/hippo.d

@@ -8,6 +8,9 @@ import hulk.bootinfo;
 import hulk.klog;
 import hulk.linker_addresses;
 
+/** Page size. */
+enum size_t PAGE_SIZE = 4096u;
+
 struct hippo
 {
     /**
@@ -80,7 +83,7 @@ struct hippo
                     {
                         free_page(phys);
                     }
-                    phys += 4096u;
+                    phys += PAGE_SIZE;
                 }
             }
         }

src/hulk/hurl.d

@@ -112,7 +112,7 @@ struct hurl
                 else
                 {
                     PageTable * next_pt = cast(PageTable *)hippo.allocate_page();
-                    memset32(next_pt, 0, 4096u / 4u);
+                    memset64(next_pt, 0u, PAGE_SIZE / 8u);
                     (*pt)[virtual, level] = PageTableEntry(next_pt, MAP_WRITABLE | MAP_PRESENT);
                     pt = next_pt;
                 }