diff --git a/deno_test_wasm/test_wasm/Cargo.lock b/deno_test_wasm/test_wasm/Cargo.lock
new file mode 100644
index 0000000..746709d
--- /dev/null
+++ b/deno_test_wasm/test_wasm/Cargo.lock
@@ -0,0 +1,5 @@
+# This file is automatically @generated by Cargo.
+# It is not intended for manual editing.
+[[package]]
+name = "test_wasm"
+version = "0.1.0"
diff --git a/deno_test_wasm/test_wasm/Cargo.toml b/deno_test_wasm/test_wasm/Cargo.toml
new file mode 100644
index 0000000..5c9cc93
--- /dev/null
+++ b/deno_test_wasm/test_wasm/Cargo.toml
@@ -0,0 +1,15 @@
+[package]
+name = "test_wasm"
+version = "0.1.0"
+authors = ["Hatter Jiang <jht5945@gmail.com>"]
+edition = "2018"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[lib]
+crate-type =["cdylib"]
+
+[dependencies]
+
+[profile.release]
+lto = true
diff --git a/deno_test_wasm/test_wasm/src/lib.rs b/deno_test_wasm/test_wasm/src/lib.rs
new file mode 100644
index 0000000..74ef50e
--- /dev/null
+++ b/deno_test_wasm/test_wasm/src/lib.rs
@@ -0,0 +1,14 @@
+use std::ffi::CString;
+use std::os::raw::c_char;
+
+#[no_mangle]
+pub extern "C" fn malloc(len: usize) -> *mut c_char {
+    let s = unsafe { CString::from_vec_unchecked(Vec::with_capacity(len)) };
+    s.into_raw()
+}
+
+pub extern "C" fn to_uppercase(ptr: *mut c_char) -> *mut c_char {
+    let s = unsafe { CString::from_raw(ptr) };
+    let s2 = CString::new(s.to_string_lossy().to_uppercase()).unwrap();
+    s2.into_raw()
+}
\ No newline at end of file