Munimal C-Lua library

#include "lua/lua.h"
#include "lua/lauxlib.h"

int lua_summ(lua_State *L){
    double a = luaL_checknumber(L, 1); /* get first arg */
    double b = luaL_checknumber(L, 2); /* get second arg */
    lua_pushnumber(L, a + b);          /* return function value */
    return 1;                          /* count of args returned to lua */
}

#if defined(_WIN32) || defined(_WIN64) /* windows compat */
__declspec(dllexport)
#endif
int luaopen_mylib(lua_State *L) {       /* compile it to mylib.dll or mylib.so */
    lua_newtable(L);                    /* create table */
        lua_pushstring(L, "summ");      /* push "summ" as key*/
        lua_pushcfunction(L, lua_summ); /* push lua_summ as value*/
        lua_rawset(L, -3);              /* assign key and value to this table (it gone from stack, but not table) */

    return 1; /* return table to lua */
}

/*
    -- compile command like this:
    -- tcc -shared -L./path_to_lua.lib -I./path_to_lua.h -llua51 main.c -o ./mylib.dll

    -- Usage on lua-side:
    local lib = require'mylib'
    print(lib.summ(10, 20)) --> 30
*/