add lua experiment

.gitignore

@@ -15,3 +15,4 @@ multibrot
 multibrot.png
 bloom
 wo-lernen
+lua-foo

Makefile

@@ -1,7 +1,7 @@
 CFLAGS=-std=c99 -Wall -g -O2
 INDENTOPTS=-kr --no-tabs --braces-on-func-def-line --indent-level2
 
-TARGETS=approximate-pi linked-list mandelbrot threads circular-buffer structs ncurses-pong bit-fuckery bit-fuckery2 checkcheck multibrot bloom wo-lernen
+TARGETS=approximate-pi linked-list mandelbrot threads circular-buffer structs ncurses-pong bit-fuckery bit-fuckery2 checkcheck multibrot bloom wo-lernen lua-foo
 EXTRAS=mandelbrot.bmp multibrot.png
 
 .PHONY: all
@@ -31,3 +31,6 @@ multibrot: multibrot.c
 
 multibrot.png: multibrot
 	./multibrot -j2
+
+lua-foo: lua-foo.c
+	$(CC) $(CFLAGS) -o $@ $< -llua -lm

lua-foo.c

@@ -0,0 +1,61 @@
+/*
+ * Based on:
+ *
+ * http://heavycoder.com/tutorials/lua_embed.php
+ * http://www.lua.org/pil/26.html
+ * http://cc.byexamples.com/2008/06/07/how-to-embed-lua-51-in-c/
+ *
+ */
+
+#include <stdarg.h>
+#include <stdlib.h>
+#include <stdio.h>
+
+#include <lua.h>
+#include <lualib.h>
+#include <lauxlib.h>
+
+#include <math.h>
+
+void error(lua_State *L, const char *fmt, ...) {
+  va_list argp;
+  va_start(argp, fmt);
+  vfprintf(stderr, fmt, argp);
+  va_end(argp);
+  lua_close(L);
+  exit(EXIT_FAILURE);
+}
+
+/* Provided to Lua as 'mysin' later. */
+static int l_mysin(lua_State *L) {
+  double d = luaL_checknumber(L, 1);  /* get argument */
+
+  lua_pushnumber(L, sin(d));  /* push result */
+  return 1;  /* number of results */
+}
+
+int main(void) {
+  /* Set up Lua. */
+  lua_State *L;
+  L = lua_open();
+
+  luaopen_base(L);
+  luaopen_string(L);
+  /* Alternatively:
+  luaL_openlibs(L); */
+
+  /* Register 'mysin'. */
+  lua_pushcfunction(L, l_mysin);
+  lua_setglobal(L, "mysin");
+
+  /* Load and run Lua file. */
+  const char* filename = "lua-foo.lua";
+  if (luaL_loadfile(L, filename) || lua_pcall(L, 0, 0, 0))
+    error(L, "cannot run file: %s\n", lua_tostring(L, -1));
+
+  /* Clean up. */
+  lua_close(L);
+
+  /* Quit. */
+  exit(EXIT_SUCCESS);
+}

lua-foo.lua

@@ -0,0 +1,6 @@
+-- foo()
+for x = 0.00, 3.14, 0.20 do
+  print(string.format("mysin(%03.2f) = %03.2f", x, mysin(x)))
+
+  -- mysin("foo")
+end