1 files changed, 47 insertions, 0 deletions
diff --git a/src/gl/windows-once.h b/src/gl/windows-once.h
new file mode 100644
index 0000000..9dfbf3f
--- /dev/null
+++ b/src/gl/windows-once.h
@@ -0,0 +1,47 @@
+/* Once-only control (native Windows implementation).
+   Copyright (C) 2005-2021 Free Software Foundation, Inc.
+
+   This program is free software; you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 3, or (at your option)
+   any later version.
+
+   This program 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 General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program; if not, see <https://www.gnu.org/licenses/>.  */
+
+/* Written by Bruno Haible <bruno@clisp.org>, 2005.
+   Based on GCC's gthr-win32.h.  */
+
+#ifndef _WINDOWS_ONCE_H
+#define _WINDOWS_ONCE_H
+
+#define WIN32_LEAN_AND_MEAN  /* avoid including junk */
+#include <windows.h>
+
+typedef struct
+        {
+          volatile int inited;
+          volatile LONG started;
+          CRITICAL_SECTION lock;
+        }
+        glwthread_once_t;
+
+#define GLWTHREAD_ONCE_INIT { -1, -1 }
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+extern void glwthread_once (glwthread_once_t *once_control,
+                            void (*initfunction) (void));
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* _WINDOWS_ONCE_H */