Arrays 在Go中调用WebAssembly代码时如何使用Go切片？

我想在Go中使用WebAssembly计算数组的和：

package main

import (
    "encoding/binary"
    "encoding/hex"
    "fmt"

    wasm "github.com/wasmerio/go-ext-wasm/wasmer"
)

const length int32 = 4

func main() {
    // Instantiate the module.
    wasmbyte, _ := wasm.ReadBytes("test.wasm")
    instance, _ := wasm.NewInstance(wasmbyte)
    defer instance.Close()
    hasmemory := instance.HasMemory()
    fmt.Println("it has memory:", (hasmemory))

    a := []int32{1, 2, 3, 4}
    var i int32
    var ptr [length]*int32

    for i = 0; i < length; i++ {
        ptr[i] = &a[i]
        fmt.Printf("Value of a[%d] = %d\n", i, *ptr[i])

        // pass int value
        // lengths := binary.LittleEndian.Uint32(a)
        // fmt.Printf("customLen=%d\n", int32(lengths))
        // result := int32(lengths)

        allocateResult, err := instance.Exports["bar"](*ptr[i], length)
        if err != nil {
            fmt.Println("error is here", err)
        }

        binary.LittleEndian.PutUint32(instance.Memory.Data()[0:4], uint32(length))

        inputPointer := allocateResult.ToI32()

        //  Write the subject into the memory.
        memory := instance.Memory.Data()[inputPointer:]
        binary.LittleEndian.Uint32(memory)

        resp := hex.EncodeToString(memory)
        fmt.Println("resp:", resp)

    }
}

---

感谢将数据复制到WebAssembly内存，例如WebAssembly内存地址0:

    a := []int32{10, 20, 30, 40}
    // Copy data to wasm memory:
    bytes := instance.Memory.Data()
    for i, v := range a {
        binary.LittleEndian.PutUint32(bytes[4*i:], uint32(v))
    }

从WebAssembly实例获取导出的bar函数：

    bar := instance.Exports["bar"]

使用WebAssembly内存地址和长度调用导出的函数：

    result, err := bar(0, 4)
    if err != nil {
        panic(err)
    }

    fmt.Println(result)

main.go文件：

输出转到运行main.go：

以下src/lib.rs文件具有相同的wasm二进制文件，因为Rust切片只有指针和长度：

    result, err := bar(0, 4)
    if err != nil {
        panic(err)
    }

    fmt.Println(result)

[没有损坏] 发布外部C fn条切片：&[i32]->i32{ slice.iter.sum } 转换为test.wasm：

rustc-目标wasm32未知-O-板条箱类型=cdylib src/lib.rs-O test.wasm 输出转换为wasm2wat test.wasm-o test.wat以查看函数$bar arguments param i32 i32：

---

谢谢你的回答。为什么我需要在lib.rs中添加锈代码我不能使用main.rs吗？并且想要使用cargo build-target=wasm32 UnknownUp，这两个代码都在工作。但是在lib.rs中编写代码时，使用此命令rustc-target wasm32 unknown-O-cratetype=cdylib src/lib.rs-O test.wasm。我想知道为什么它对cargo build不起作用。我添加了这一点，并在运行go代码时仍然运行cargo build。结果是0 Let us。

it has memory: true
100

(module
  (type (;0;) (func (param i32 i32) (result i32)))
  (func $bar (type 0) (param i32 i32) (result i32)
    (local i32)
    block  ;; label = @1
      local.get 1
      br_if 0 (;@1;)
      i32.const 0
      return
    end
    local.get 1
    i32.const 2
    i32.shl
    local.set 2
    i32.const 0
    local.set 1
    loop  ;; label = @1
      local.get 0
      i32.load
      local.get 1
      i32.add
      local.set 1
      local.get 0
      i32.const 4
      i32.add
      local.set 0
      local.get 2
      i32.const -4
      i32.add
      local.tee 2
      br_if 0 (;@1;)
    end
    local.get 1)
  (table (;0;) 1 1 funcref)
  (memory (;0;) 16)
  (global (;0;) (mut i32) (i32.const 1048576))
  (global (;1;) i32 (i32.const 1048576))
  (global (;2;) i32 (i32.const 1048576))
  (export "memory" (memory 0))
  (export "bar" (func $bar))
  (export "__data_end" (global 1))
  (export "__heap_base" (global 2)))