Added running WASM within the zkvm example (risc0#539)

* Added a example that runs the supplied WASM bytecode within the zkvm and
commits the results. Using a simple fib() WAT module as an example
function

examples/Cargo.toml

@@ -14,6 +14,7 @@ members = [
     "sha",
     "waldo",
     "waldo/core",
+    "wasm",
     "wordle",
     "wordle/core",
 ]

examples/wasm/Cargo.toml

@@ -0,0 +1,15 @@
+[package]
+name = "wasm"
+version = "0.1.0"
+edition = "2021"
+
+[dependencies]
+risc0-zkvm = { path = "../../risc0/zkvm" }
+serde = "1.0"
+wasm-methods = { path = "methods" }
+wat = "1.0"
+
+[features]
+cuda = ["risc0-zkvm/cuda"]
+default = []
+metal = ["risc0-zkvm/metal"]

examples/wasm/README.md

@@ -0,0 +1,9 @@
+# WASM
+
+Example of running WASM code within the ZKVM using the [wasmi](https://crates.io/crates/wasmi) crate. In this example we define a fibonacci function in WAT format, compile it to WASM bytecode then run it within the ZKVM guest code. Returning the result of the fib() function back to the host. This sample can be extended to run arbitrary WAT/WASM modules or run a specific WASM bytecode if you compile the WASM code into the guest image.
+
+## Running
+
+```bash
+cargo run --release
+```

examples/wasm/methods/Cargo.toml

@@ -0,0 +1,10 @@
+[package]
+name = "wasm-methods"
+version = "0.1.0"
+edition = "2021"
+
+[build-dependencies]
+risc0-build = { path = "../../../risc0/build" }
+
+[package.metadata.risc0]
+methods = ["guest"]

examples/wasm/methods/build.rs

@@ -0,0 +1,17 @@
+// Copyright 2023 RISC Zero, Inc.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+fn main() {
+    risc0_build::embed_methods();
+}