https://github.com/goccy/cgo-math
Generate libm bridge for resolving undefined symbol in cgo
https://github.com/goccy/cgo-math
cgo cgo-bindings go golang math
Last synced: 4 months ago
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Generate libm bridge for resolving undefined symbol in cgo
- Host: GitHub
- URL: https://github.com/goccy/cgo-math
- Owner: goccy
- Created: 2020-03-11T06:53:08.000Z (over 5 years ago)
- Default Branch: master
- Last Pushed: 2020-03-11T09:11:49.000Z (over 5 years ago)
- Last Synced: 2025-01-22T14:08:15.668Z (9 months ago)
- Topics: cgo, cgo-bindings, go, golang, math
- Language: Go
- Homepage:
- Size: 7.81 KB
- Stars: 3
- Watchers: 2
- Forks: 1
- Open Issues: 0
-
Metadata Files:
- Readme: README.md
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README
# cgo-math
Generate libm bridge for resolving undefined symbol in cgo
# Example
( Put same example in `_example` directory )
### Working Tree
```
$ tree
.
├── ccall
│ ├── ccall.c
│ └── ccall.go
├── go.mod
├── go.sum
└── main.go
```
### Contents
- `go.mod`
```
module example
go 1.12
```
- `main.go`
Only call `ccall.Sqrt(float64)float64` .
```go
package main
import (
"example/ccall"
"fmt"
)
func main() {
fmt.Println(ccall.Sqrt(4))
}
```
- `ccall/ccall.go`
define `Sqrt(float64)float64` and call C API ( `double callSqrt(double x)` )
```go
package ccall
// extern double callSqrt(double x);
import "C"
func Sqrt(x float64) float64 {
return float64(C.callSqrt(C.double(x)))
}
```
- `ccall/ccall.c`
define `double callSqrt(double)` and call `sqrt`
```c
#include "_cgo_export.h"
double callSqrt(double x) {
return sqrt(x);
}
```
### Run example
```bash
$ go run main.go
# example/ccall
ccall.c:4:10: warning: implicitly declaring library function 'sqrt' with type 'double (double)' [-Wimplicit-function-declaration]
ccall.c:4:10: note: include the header or explicitly provide a declaration for 'sqrt'
2
```
Produce **warning: implicitly declaring** because this example doesn't link `libm` .
### Executes cgo-math-bindgen
#### Install CLI
```bash
go get github.com/goccy/cgo-math/cmd/cgo-math-bindgen
```
#### Run generator
```bash
$ cgo-math-bindgen --package ccall --output ccall
```
Generate bridge source to `ccall/bridge_math.go` as `ccall` package
### Try to run example again
```bash
$ go run main.go
2
```
Yeah ! we resolved reference to `sqrt` symbol !