Function ExampleConfig_multi

example_test.go:155–238

An example of enabling the multi-value feature of WebAssembly and interacting with multi-value functions.

()

// An example of enabling the multi-value feature of WebAssembly and
// interacting with multi-value functions.
func ExampleConfig_multi() {
	// Configure our `Store`, but be sure to use a `Config` that enables the
	// wasm multi-value feature since it's not stable yet.
	config := wasmtime.NewConfig()
	config.SetWasmMultiValue(true)
	store := wasmtime.NewStore(wasmtime.NewEngineWithConfig(config))

	wasm, err := wasmtime.Wat2Wasm(`
	(module
	  (func $f (import "" "f") (param i32 i64) (result i64 i32))

	  (func $g (export "g") (param i32 i64) (result i64 i32)
	    (call $f (local.get 0) (local.get 1))
	  )

	  (func $round_trip_many
	    (export "round_trip_many")
	    (param i64 i64 i64 i64 i64 i64 i64 i64 i64 i64)
	    (result i64 i64 i64 i64 i64 i64 i64 i64 i64 i64)

	    local.get 0
	    local.get 1
	    local.get 2
	    local.get 3
	    local.get 4
	    local.get 5
	    local.get 6
	    local.get 7
	    local.get 8
	    local.get 9
	  )
	)
	`)
	if err != nil {
		log.Fatal(err)
	}
	module, err := wasmtime.NewModule(store.Engine, wasm)
	if err != nil {
		log.Fatal(err)
	}

	callback := wasmtime.WrapFunc(store, func(a int32, b int64) (int64, int32) {
		return b + 1, a + 1
	})

	instance, err := wasmtime.NewInstance(store, module, []wasmtime.AsExtern{callback})
	if err != nil {
		log.Fatal(err)
	}

	g := instance.GetFunc(store, "g")

	results, err := g.Call(store, 1, 3)
	if err != nil {
		log.Fatal(err)
	}
	arr := results.([]wasmtime.Val)
	a := arr[0].I64()