From 2417a6b7603524dc5cd30d29b153f91024b9443d Mon Sep 17 00:00:00 2001
From: Mitja Felicijan <mitja.felicijan@gmail.com>
Date: Wed, 1 Nov 2023 22:54:27 +0100
Subject: Move to Jekyll

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+---
+title: Extend Lua with custom C functions using Clang
+permalink: /extend-lua-with-custom-c.html
+date: 2023-05-23T12:00:00+02:00
+layout: post
+type: note
+draft: false
+tags: [lua, c]
+---
+
+Here is a boilerplate for extending Lua with custom C functions. This requires
+Clang and Lua 5.1 to be installed. GCC can be used instead of Clang, but the
+Makefile will need to be modified.
+
+- nativefunc.c
+
+  ```c
+  #include <lua.h>
+  #include <lauxlib.h>
+
+  static int l_mult50(lua_State *L) {
+    double number = luaL_checknumber(L, 1);
+    lua_pushnumber(L, number * 50);
+    return 1;
+  }
+
+  int luaopen_nativefunc(lua_State *L) {
+    static const struct luaL_Reg nativeFuncLib[] = { {"mult50", l_mult50}, {NULL, NULL} };
+
+    luaL_register(L, "nativelib", nativeFuncLib);
+    return 1;
+  }
+  ```
+
+- main.lua
+
+  ```lua
+  require "nativefunc"
+  print(nativelib.mult50(50))
+  ```
+
+- Makefile
+
+  ```Makefile
+  CC       = clang
+  CFLAGS   =
+  INCLUDES = `pkg-config lua5.1 --cflags-only-I`
+
+  all:
+    $(CC) -shared -o nativefunc.so -fPIC nativefunc.c $(CFLAGS) $(INCLUDES)
+
+  clean:
+    rm *.so
+  ```
+
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