Potentially fix a double page fault issue under certain conditions

src/memory.rs

@@ -232,13 +232,16 @@ impl Memory {
 
     pub fn write_8(&mut self, mut address: u32, byte: u8) {
         let mut writable = true;
+        let mut ok = true;
         if *self.mmu_enabled() {
             (address, writable) = self.virtual_to_physical(address as u32).unwrap_or_else(|| {
                 self.exception_sender().send(Exception::PageFaultWrite(address)).unwrap();
+                ok = false;
                 (0, false)
             });
         }
 
+        if ok {
             if writable {
                 let address = address as usize;
 
@@ -258,6 +261,7 @@ impl Memory {
                 self.exception_sender().send(Exception::PageFaultWrite(address)).unwrap();
             }
         }
+    }
     pub fn write_16(&mut self, address: u32, half: u16) {
         self.write_8(address, (half & 0x00FF) as u8);
         self.write_8(address + 1, (half >> 8) as u8);