emu: ROL/ROR operations

src/emu/flags.rs

@@ -87,11 +87,22 @@ impl Flags {
       OperandWidth::Word => 0x8000,
     }
   }
+
+  // The rotate ops update OF don't touch PF/AF/ZF/SF so we make
+  // everything eager so they don't get clobbered
+  pub fn update_of(&mut self, of: bool) {
+    let mut flags = (*self).into();
+    flags &= !(1 << OF_BIT);         // Mask out old OF Flag
+    if of { flags |= 1 << OF_BIT; }  // Mask in new OF Flag
+
+    self.flag_op = FlagOp::Eager;
+    self.res = flags;
+  }
 }
 
 #[derive(Clone, Copy)]
 pub enum FlagOp {
-  Eager,  // precomputed into result, for e.g. POPF? (Anything else?)
+  Eager,  // precomputed into result, for POPF or anything that changes only some flags
   DEC,
   INC,
   SHIFT,