I'm working on porting legacy code to golang, the code is high performance and I'm having trouble translating a part of the program that reads of a shared memory for later parsing. In c I would just cast the memory into a struct and access it normally. What is the most efficient and idiomatic to achieve the same result in go?
1条回答 默认 最新
- dqvs45976 2015-02-16 15:58关注
If you want to cast an array of bytes to a struct, the unsafe package can do it for you. Here is a working example:
There are limitations to the struct field types you can use in this way. Slices and strings are out, unless your C code yields exactly the right memory layout for the respective slice/string headers, which is unlikely. If it's just fixed size arrays and types like (u)int(8/16/32/64), the code below may be good enough. Otherwise you'll have to manually copy and assign each struct field by hand.
package main import "fmt" import "unsafe" type T struct { A uint32 B int16 } var sizeOfT = unsafe.Sizeof(T{}) func main() { t1 := T{123, -321} fmt.Printf("%#v ", t1) data := (*(*[1<<31 - 1]byte)(unsafe.Pointer(&t1)))[:sizeOfT] fmt.Printf("%#v ", data) t2 := (*(*T)(unsafe.Pointer(&data[0]))) fmt.Printf("%#v ", t2) }
Note that
(*[1<<31 - 1]byte)
does not actually allocate a byte array of this size. It's a trick used to ensure a slice of the correct size can be created through the...[:sizeOfT]
part. The size1<<31 - 1
is the largest possible size any slice in Go can have. At least this used to be true in the past. I am unsure of this still applies. Either way, you'll have to use this approach to get a correctly sized slice of bytes.本回答被题主选为最佳回答 , 对您是否有帮助呢?解决 无用评论 打赏 举报
悬赏问题
- ¥15 没输出运行不了什么问题
- ¥20 输入import torch显示Intel MKL FATAL ERROR,系统驱动1%,: Cannot load mkl_intel_thread.dll.
- ¥15 点云密度大则包围盒小
- ¥15 nginx使用nfs进行服务器的数据共享
- ¥15 C#i编程中so-ir-192编码的字符集转码UTF8问题
- ¥15 51嵌入式入门按键小项目
- ¥30 海外项目,如何降低Google Map接口费用?
- ¥15 fluentmeshing
- ¥15 手机/平板的浏览器里如何实现类似荧光笔的效果
- ¥15 盘古气象大模型调用(python)