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doc How-to-migrate-a-C&C++-Library

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xushiwei
2024-07-18 23:35:39 +08:00
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doc/llgo_migration_for_c_c++_third-party_libraries.md → doc/How-to-migrate-a-C&C++-Library.md
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@@ -1,39 +1,29 @@
# LLGO Migration for C/C++ Third-Party Libraries # How to migrate a C/C++ Library
# LLGO Migration for C Third-Party Libraries # Migrate a C Library
## Installing Third-Party Libraries ## Install a C Library
### Using Package Manager to Download We recommend using a package manager (such as brew, apt-get, winget, etc.) to install a C library. For example:
```bash ```bash
brew install inih brew install inih
``` ```
### Compiling from Source
```bash
# Compile dylib from source
clang++ -dynamiclib x.cpp -o {users third-party libraries path}/lib/libbar.dylib -lfmt -std=c++11
# Generate pc for the corresponding dylib
# Install via `https://github.com/hackerchai/dylib-installer`
```
## Writing Go Files to Link Library Functions ## Writing Go Files to Link Library Functions
1. On macOS, use `nm -gU libbar.dylib` to parse C-style symbols 1. On macOS, use `nm -gU libbar.dylib` to parse C-style symbols
```jsx ```jsx
0000000000003e55 T _ini_parse 0000000000003e55 T _ini_parse
```
```
2. Find the function prototype you want to convert in the corresponding .h file 2. Find the function prototype you want to convert in the corresponding .h file
```c ```c
int ini_parse(const char* filename, ini_handler handler, void* user); int ini_parse(const char* filename, ini_handler handler, void* user);
```
```
3. Create the corresponding Go file 3. Create the corresponding Go file
```c ```c
@@ -46,19 +36,18 @@ clang++ -dynamiclib x.cpp -o {users third-party libraries path}/lib/libbar.dylib
``` ```
4. In `inih.go`, use LLGoPackage to specify the location of the third-party library so that llgo can link to the third-party library. Both `pkg-config --libs inih` and `linih` are used to specify the location of the third-party library. 4. In `inih.go`, use LLGoPackage to specify the location of the third-party library so that llgo can link to the third-party library. Both `pkg-config --libs inih` and `linih` are used to specify the location of the third-party library.
```go ```go
package inih package inih
import ( import (
// Using go:linkname unsafe is necessary for the next step _ "unsafe" // unsafe is necessary when using go:linkname
_ "unsafe" )
)
const ( const (
LLGoPackage = "link: $(pkg-config --libs inih); -linih" LLGoPackage = "link: $(pkg-config --libs inih); -linih"
) )
```
```
5. Write the corresponding function in `inih.go` 5. Write the corresponding function in `inih.go`
Note that the basic C function type mapping to Go function type can be found at [https://github.com/goplus/llgo/blob/main/doc/Type-Mapping-between-C-and-Go.md](https://github.com/goplus/llgo/blob/main/doc/Type-Mapping-between-C-and-Go.md). Some types requiring special handling are listed at the end of this document for reference. Note that the basic C function type mapping to Go function type can be found at [https://github.com/goplus/llgo/blob/main/doc/Type-Mapping-between-C-and-Go.md](https://github.com/goplus/llgo/blob/main/doc/Type-Mapping-between-C-and-Go.md). Some types requiring special handling are listed at the end of this document for reference.
@@ -66,12 +55,11 @@ clang++ -dynamiclib x.cpp -o {users third-party libraries path}/lib/libbar.dylib
```go ```go
//go:linkname Parse C.ini_parse //go:linkname Parse C.ini_parse
func Parse(filename *c.Char, handler func(user c.Pointer, section *c.Char, name *c.Char, value *c.Char) c.Int, user c.Pointer) c.Int func Parse(filename *c.Char, handler func(user c.Pointer, section *c.Char, name *c.Char, value *c.Char) c.Int, user c.Pointer) c.Int
``` ```
6. Write the function call in `inih_demo.go` 6. Write the function call in `inih_demo.go`
```go ```go
package main package main
import ( import (