PageTableEntry improvements

- fix alias this
- add properties for dirty/accessed
- add opIndex for direct indexing

src/hulk/pagetable.d

@@ -22,7 +22,7 @@ enum ulong PT_NO_EXECUTE = 0x8000_0000_0000_0000u;
 struct PageTableEntry
 {
     /** The raw page table entry is a 64-bit ulong. */
-    private ulong entry;
+    public ulong entry;
     alias entry this;
 
     /**
@@ -102,6 +102,22 @@ struct PageTableEntry
         return (entry & PT_NO_EXECUTE) != 0u;
     }
 
+    /**
+     * Return whether the page is dirty.
+     */
+    public @property bool dirty() const
+    {
+        return (entry & PT_DIRTY) != 0u;
+    }
+
+    /**
+     * Return whether the page is accessed.
+     */
+    public @property bool accessed() const
+    {
+        return (entry & PT_ACCESSED) != 0u;
+    }
+
     /**
      * Follow the page table entry to the next page table it points to.
      */
@@ -146,5 +162,18 @@ struct PageTable
     {
         return (cast(ulong)address >> (39u - (9u * level))) & 0x1FFu;
     }
+
+    /**
+     * Access a page table entry by linear index.
+     *
+     * @param index
+     *   Page table index (0-511).
+     *
+     * @return PageTableEntry at the given index.
+     */
+    public PageTableEntry opIndex(size_t index)
+    {
+        return entries[index];
+    }
 }
 static assert(PageTable.sizeof == 4096u);