implement unsigned operators

src/ast.rs

@@ -170,19 +170,25 @@ pub enum BinOp {
     Sub,
     Mul,
     Div,
+    DivU,
     Rem,
+    RemU,
     And,
     Or,
     Xor,
     Eq,
     Ne,
     Gt,
+    GtU,
     Ge,
+    GeU,
     Lt,
+    LtU,
     Le,
-    Lsl,
-    Lsr,
-    Asr,
+    LeU,
+    Shl,
+    ShrU,
+    ShrS,
 }
 
 #[derive(Debug, Clone, Copy, PartialEq, Eq)]