Add alternative paging module with new design

src/memory/paging_new/mod.rs

@@ -0,0 +1,49 @@
+mod entry;
+mod table;
+mod levels;
+mod translate;
+
+pub const PAGE_SIZE: usize = 4096;
+const ENTRY_SIZE: usize = 8;
+const ENTRY_COUNT: usize = 512;
+
+pub type PhysicalAddress = usize;
+pub type VirtualAddress = usize;
+
+pub struct Page {
+    number: usize,
+}
+
+impl Page {
+    fn containing_address(address: VirtualAddress) -> Page {
+        match address {
+            addr if addr < 0o_400_000_000_000_0000 => Page { number: addr / PAGE_SIZE },
+            addr if addr >= 0o177777_400_000_000_000_0000 => {
+                Page { number: (address / PAGE_SIZE) & 0o_777_777_777_777 }
+            }
+            _ => panic!("invalid address: 0x{:x}", address),
+        }
+    }
+
+    pub fn start_address(&self) -> VirtualAddress {
+        if self.number >= 0x800000000 {
+            // sign extension necessary
+            (self.number << 12) | 0xffff_000000000000
+        } else {
+            self.number << 12
+        }
+    }
+
+    fn p4_index(&self) -> usize {
+        (self.number >> 27) & 0o777
+    }
+    fn p3_index(&self) -> usize {
+        (self.number >> 18) & 0o777
+    }
+    fn p2_index(&self) -> usize {
+        (self.number >> 9) & 0o777
+    }
+    fn p1_index(&self) -> usize {
+        (self.number >> 0) & 0o777
+    }
+}