Adding code for early init and late deinitialiation functions.

The early initialization functions are called before main() is called. They
correspond to early constructor calls in C++.  The deinitialization functions
are the mirror image.  They are called after main exits.

Author: kyle-github

earlyinit/earlyinit.h

@@ -0,0 +1,47 @@
+/* RLIB - Convenience library for useful things
+ * Copyright (C) 2015-2016  Haakon Sporsheim <[email protected]>
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 3.0 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library.
+ * See the COPYING file at the root of the source repository.
+ */
+
+
+/*
+ * Modified by Kyle Hayes.  I just want the early init stuff.
+ */
+
+#ifndef __R_MACROS_H__
+#define __R_MACROS_H__
+
+#if defined(__GNUC__)
+#define R_INITIALIZER(f)   static void __attribute__((constructor)) f (void)
+#define R_DEINITIALIZER(f) static void __attribute__((destructor))  f (void)
+#elif defined(_MSC_VER)
+#define R_INITIALIZER(f)                                                    \
+  static void __cdecl f (void);                                             \
+  __pragma(section(".CRT$XCU",read))                                        \
+  __declspec(allocate(".CRT$XCU")) void (__cdecl*f##_)(void) = f;           \
+  static void __cdecl f (void)
+#define R_DEINITIALIZER(f)                                                  \
+  static void __cdecl f (void);                                             \
+  static void __cdecl f##_atexit (void) { atexit (f); }                     \
+  __pragma(section(".CRT$XCU",read))                                        \
+  __declspec(allocate(".CRT$XCU")) void (__cdecl*f##_)(void) = f##_atexit;  \
+  static void __cdecl f (void)
+#else
+#error Your compiler does not support initializers/deinitializers
+#endif
+
+
+#endif /* __R_MACROS_H__ */

earlyinit/test_earlyinit.c

@@ -0,0 +1,40 @@
+
+#include <stdio.h>
+#include <stdlib.h>
+#include "earlyinit.h"
+
+
+static int test_val = 4;
+static void *test_allocation = NULL;
+
+R_INITIALIZER(test_initializer)
+{
+    printf("Test initializer called.\n");
+
+    test_val = 42;
+
+    test_allocation = malloc(1024);
+}
+
+R_DEINITIALIZER(test_deinitializer)
+{
+    printf("Test deinitializer called.\n");
+
+    test_val = 4;
+
+    free(test_allocation);
+}
+
+
+
+
+int main(int argc, char **argv)
+{
+    printf("test_val = %d\n",test_val);
+
+    printf("test_allocation=%p\n",test_allocation);
+
+    return 0;
+}
+
+