wasmexec

README

wasmexec

• wasmexec is a utility to execute WebAssembly in Go with interface similar to WebAssembly.instantiateStreaming().
• This package is using wagon as an interpreter of WebAssembly.

Usage

1. Create Wasm binary

• multiply.wat

(module
  (import "go" "imultiply" (func $imultiply (param $a i32) (param $b i32) (result i32)))
  (func (export "multiply") (param $a i32) (param $b i32) (result i32)
    local.get $a
    local.get $b
    call $imultiply)
)

$ wat2wasm multiply.wat

2. Read Wasm binary and execute exported function

• main.go

// 1. Open Wasm binary
f, _ := os.Open("exmaple.wasm")
defer f.Close()

// 2. Create ImportObject
importObject := wasmexec.ImportObject{
    "go": {
        "imultiply": func(a int, b int) int{
            return a * b
        },
    },
}

// 3. Initialize WebAssembly instance
inst, _ := wasmexec.InstantiateStreaming(f, importObject)

// 4. Call exported function
result, _ := inst.Call("multiply", uint64(2), uint64(3))
fmt.Println(result) // #=> 6

For details, please see examples/multiply.

Supported Features

• import func
• import global
• import memory

License

MIT

Author

syumai

Documentation

Index

• Constants
• type ImportObject
• type Instance
  • func InstantiateStreaming(src io.Reader, importObject ImportObject) (*Instance, error)
  • func (i *Instance) Call(name string, args ...uint64) (uint64, error)
• type Memory
  • func NewMemory(initial uint32, maximum uint32) *Memory
  • func (m *Memory) Buffer() []byte

Constants

const MemoryPageSize = 65536 // 64KiB

Types

type ImportObject

type ImportObject map[string]map[string]interface{}

type Instance

type Instance struct {
	Module *wasm.Module
	VM     *exec.VM
}

func InstantiateStreaming

func InstantiateStreaming(src io.Reader, importObject ImportObject) (*Instance, error)

func (*Instance) Call

func (i *Instance) Call(name string, args ...uint64) (uint64, error)

type Memory

type Memory struct {
	// contains filtered or unexported fields
}

func NewMemory

func NewMemory(initial uint32, maximum uint32) *Memory

func (*Memory) Buffer

func (m *Memory) Buffer() []byte