Add an example of a C Lua module in the test_c comments.

1 files changed, 53 insertions, 0 deletions

diff --git a/ClientHamr/GuiLua/test_c.c b/ClientHamr/GuiLua/test_c.c
index d72067e..8c3796d 100644
--- a/ClientHamr/GuiLua/test_c.c
+++ b/ClientHamr/GuiLua/test_c.c
@@ -22,4 +22,57 @@ Though it seems that chapter 26 is not in the same place?
 http://www.lua.org/pil/26.2.html  doesn't say much really, and is for
 Lua 5.0
 
+
+
+An example -
+
+// build@ gcc -shared -I/home/sdonovan/lua/include -o mylib.so mylib.c
+// includes for your code
+#include <string.h>
+#include <math.h>
+
+// includes for Lua
+#include <lua.h>
+#include <lauxlib.h>
+#include <lualib.h>
+
+// defining functions callable from Lua
+static int l_createtable (lua_State *L) {
+  int narr = luaL_optint(L,1,0);         // initial array slots, default 0
+  int nrec = luaL_optint(L,2,0);   // intialof hash slots, default 0
+  lua_createtable(L,narr,nrec);
+  return 1;
+}
+
+static int l_solve (lua_State *L) {
+    double a = lua_tonumber(L,1);  // coeff of x*x
+    double b = lua_tonumber(L,2);  // coef of x
+    double c = lua_tonumber(L,3);  // constant
+    double abc = b*b - 4*a*c;
+    if (abc < 0.0) {
+        lua_pushnil(L);
+        lua_pushstring(L,"imaginary roots!");
+        return 2;
+    } else {
+        abc = sqrt(abc);
+        a = 2*a;
+        lua_pushnumber(L,(-b + abc)/a);
+        lua_pushnumber(L,(+b - abc)/a);
+        return 2;
+    }
+}
+
+static const luaL_reg mylib[] = {
+    {"createtable",l_createtable},
+    {"solve",l_solve},
+    {NULL,NULL}
+};
+
+int luaopen_mylib(lua_State *L)
+{
+    luaL_register (L, "mylib", mylib);
+    return 1;
+}
+
+
 */