diff --git a/__wasm/wasmtime/add.c b/__wasm/wasmtime/add.c
new file mode 100644
index 0000000..d71efc0
--- /dev/null
+++ b/__wasm/wasmtime/add.c
@@ -0,0 +1,5 @@
+// add.c
+int add (int first, int second)
+{
+  return first + second;
+}
diff --git a/__wasm/wasmtime/add.wasm b/__wasm/wasmtime/add.wasm
new file mode 100755
index 0000000..6bd522b
Binary files /dev/null and b/__wasm/wasmtime/add.wasm differ
diff --git a/__wasm/wasmtime/examples/example1.rs b/__wasm/wasmtime/examples/example1.rs
new file mode 100644
index 0000000..10fb87a
--- /dev/null
+++ b/__wasm/wasmtime/examples/example1.rs
@@ -0,0 +1,38 @@
+use anyhow::Result;
+use wasmtime::*;
+
+fn main() -> Result<()> {
+    // Modules can be compiled through either the text or binary format
+    let engine = Engine::default();
+    let wat = r#"
+        (module
+            (import "host" "hello" (func $host_hello (param i32)))
+
+            (func (export "hello")
+                i32.const 3
+                call $host_hello)
+        )
+    "#;
+    let module = Module::new(&engine, wat)?;
+
+    // Create a `Linker` which will be later used to instantiate this module.
+    // Host functionality is defined by name within the `Linker`.
+    let mut linker = Linker::new(&engine);
+    linker.func_wrap("host", "hello", |caller: Caller<'_, u32>, param: i32| {
+        println!("Got {} from WebAssembly", param);
+        println!("my host state is: {}", caller.data());
+    })?;
+
+    // All wasm objects operate within the context of a "store". Each
+    // `Store` has a type parameter to store host-specific data, which in
+    // this case we're using `4` for.
+    let mut store = Store::new(&engine, 4);
+    let instance = linker.instantiate(&mut store, &module)?;
+    let hello = instance.get_typed_func::<(), (), _>(&mut store, "hello")?;
+
+    // And finally we can call the wasm!
+    hello.call(&mut store, ())?;
+
+    Ok(())
+}
+
diff --git a/__wasm/wasmtime/justfile b/__wasm/wasmtime/justfile
new file mode 100644
index 0000000..84c7ae3
--- /dev/null
+++ b/__wasm/wasmtime/justfile
@@ -0,0 +1,12 @@
+_:
+  @just --list
+
+# https://git.hatter.ink/hatter/learn_programming/src/branch/master/webassembly/clang-llvm.md
+compile_add_wasm:
+  export PATH=/usr/local/opt/llvm/bin:$PATH
+  clang --target=wasm32 --no-standard-libraries -Wl,--export-all -Wl,--no-entry -o add.wasm add.c
+
+run_example1:
+  cargo run --example example1
+
+
diff --git a/__wasm/wasmtime/src/main.rs b/__wasm/wasmtime/src/main.rs
index 10fb87a..5db05b7 100644
--- a/__wasm/wasmtime/src/main.rs
+++ b/__wasm/wasmtime/src/main.rs
@@ -3,35 +3,27 @@ use wasmtime::*;
 
 fn main() -> Result<()> {
     // Modules can be compiled through either the text or binary format
-    let engine = Engine::default();
-    let wat = r#"
-        (module
-            (import "host" "hello" (func $host_hello (param i32)))
+    // let engine = Engine::default();
+    let mut config = Config::default();
+    config.consume_fuel(true);
+    config.static_memory_maximum_size(1_000_000_u64);
+    config.dynamic_memory_guard_size(0_u64);
+    let engine = Engine::new(&config).unwrap();
 
-            (func (export "hello")
-                i32.const 3
-                call $host_hello)
-        )
-    "#;
-    let module = Module::new(&engine, wat)?;
+    let add_wasm_bytes = std::fs::read("add.wasm").expect("Read wasm failed");
+    let module = Module::new(&engine, add_wasm_bytes)?;
 
-    // Create a `Linker` which will be later used to instantiate this module.
-    // Host functionality is defined by name within the `Linker`.
-    let mut linker = Linker::new(&engine);
-    linker.func_wrap("host", "hello", |caller: Caller<'_, u32>, param: i32| {
-        println!("Got {} from WebAssembly", param);
-        println!("my host state is: {}", caller.data());
-    })?;
-
-    // All wasm objects operate within the context of a "store". Each
-    // `Store` has a type parameter to store host-specific data, which in
-    // this case we're using `4` for.
+    let linker = Linker::new(&engine);
     let mut store = Store::new(&engine, 4);
     let instance = linker.instantiate(&mut store, &module)?;
-    let hello = instance.get_typed_func::<(), (), _>(&mut store, "hello")?;
+    let hello = instance.get_typed_func::<(i32, i32), i32, _>(&mut store, "add")?;
 
-    // And finally we can call the wasm!
-    hello.call(&mut store, ())?;
+    store.add_fuel(10_000_u64).ok();
+
+    println!("1 + 2 = {:?}", hello.call(&mut store, (1, 2))?);
+    println!("Fuel consumed: {:?}", store.fuel_consumed());
+    println!("2 + 3 = {:?}", hello.call(&mut store, (2, 3))?);
+    println!("Fuel consumed: {:?}", store.fuel_consumed());
 
     Ok(())
 }