implement basic structs and traits for uint256, uint128, uint160

src/lib.rs

@@ -44,6 +44,53 @@ fn unsafe_alloc_buffer(len: usize) -> Vec<u8> {
     ret
 }
 
+#[derive(Copy, Clone)]
+pub struct Uint160 {
+    bytes: [u8; 20],
+}
+
+#[derive(Copy, Clone)]
+pub struct Uint256 {
+    bytes: [u8; 32],
+}
+
+#[derive(Copy, Clone)]
+pub struct Uint128 {
+    bytes: [u8; 16],
+}
+
+trait EwasmType {
+    fn new() -> Self;
+}
+
+type Address = Uint160;
+type Hash = Uint256;
+type Value = Uint128;
+
+impl EwasmType for Address {
+    fn new() -> Self {
+        Address {
+            bytes: [0; 20],
+        }
+    }
+}
+
+impl EwasmType for Value {
+    fn new() -> Self {
+        Value {
+            bytes: [0; 16],
+        }
+    }
+}
+
+impl EwasmType for Hash {
+    fn new() -> Self {
+        Hash {
+            bytes: [0; 32],
+        }
+    }
+}
+
 pub enum CallResult {
     Successful,
     Failure,