Lua

Lua is an open source scripting language whose main purpose is being embedded in C applications. More can be learned by viewing their website at ​http://www.lua.org .

Using Lua in RTEMS

For now, you can find the lua rtems files at ​http://gwu.webhop.net/~cssmith/GSOC/index.html

Calling Lua Functions in C

This operates exactly as it would in the host operating system.

        #include <rtems/lua.h>
        #include <rtems/lualib.h>
        #include <rtems/lauxlib.h>
        //This is the reference to the lua interpreter
        lua_State* L;
        
        rtems_task Init(
          rtems_task_argument ignored
        )
        {
          L = lua_open();
          luaL_openlibs(L);
          
          //Test of basic lua functionality
          lua_getglobal(L, "print");
          lua_pushstring(L, "Hello, Lua!");
          lua_call(L, 1, 0);
          lua_close(L);
       }

Spawning a Lua Shell

_Lua_Main(int argc, char** argv) is a standard C main function. Lua spawns a shell whenever it is called without a script as an argument. Therefore, the end user can spawn a lua shell by modifying the code below:

        #include <rtems/lua.h>
        #include <rtems/lualib.h>
        #include <rtems/lauxlib.h>
        	    
        rtems_task Init(
          rtems_task_argument ignored
        )
        {
          _Lua_spawn_shell();
        }

Spawning a RTEMS Shell

This creates a lua shell that allows for the execution of RTEMS commands.

        #include <rtems/lua.h>
        #include <rtems/lualib.h>
        #include <rtems/lauxlib.h>
        	    
        rtems_task Init(
          rtems_task_argument ignored
        )
        {
          _Lua_spawn_RTEMS_shell();
        }

Executing a Standalone Lua Script

Since _Lua_Main(int argc, char** argv) is a standard C main function, executing lua scripts are as simple as notifying the interpreter where the file is located.

Note: This currently has only been tested with the IMFS? in RTEMS. Technically speaking, it should work agnostic to the underlying filesystem.

        #include <rtems/lua.h>
        #include <rtems/lualib.h>
        #include <rtems/lauxlib.h>
        	    
        rtems_task Init(
          rtems_task_argument ignored
        )
        {
          char** program_args = NULL;
          /*
             Setup arguments for the lua script, if any
          */
          _Lua_run_script("path-to-program.lua", num_arguments, program_args);
        }