1 files changed, 95 insertions, 0 deletions
diff --git a/gl/lib/windows-mutex.c b/gl/lib/windows-mutex.c
new file mode 100644
index 0000000..7eb38a2
--- /dev/null
+++ b/gl/lib/windows-mutex.c
@@ -0,0 +1,95 @@
+/* Plain mutexes (native Windows implementation).
+   Copyright (C) 2005-2020 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.  */
+
+#include <config.h>
+
+/* Specification.  */
+#include "windows-mutex.h"
+
+#include <errno.h>
+
+void
+glwthread_mutex_init (glwthread_mutex_t *mutex)
+{
+  InitializeCriticalSection (&mutex->lock);
+  mutex->guard.done = 1;
+}
+
+int
+glwthread_mutex_lock (glwthread_mutex_t *mutex)
+{
+  if (!mutex->guard.done)
+    {
+      if (InterlockedIncrement (&mutex->guard.started) == 0)
+        /* This thread is the first one to need this mutex.  Initialize it.  */
+        glwthread_mutex_init (mutex);
+      else
+        {
+          /* Don't let mutex->guard.started grow and wrap around.  */
+          InterlockedDecrement (&mutex->guard.started);
+          /* Yield the CPU while waiting for another thread to finish
+             initializing this mutex.  */
+          while (!mutex->guard.done)
+            Sleep (0);
+        }
+    }
+  EnterCriticalSection (&mutex->lock);
+  return 0;
+}
+
+int
+glwthread_mutex_trylock (glwthread_mutex_t *mutex)
+{
+  if (!mutex->guard.done)
+    {
+      if (InterlockedIncrement (&mutex->guard.started) == 0)
+        /* This thread is the first one to need this mutex.  Initialize it.  */
+        glwthread_mutex_init (mutex);
+      else
+        {
+          /* Don't let mutex->guard.started grow and wrap around.  */
+          InterlockedDecrement (&mutex->guard.started);
+          /* Let another thread finish initializing this mutex, and let it also
+             lock this mutex.  */
+          return EBUSY;
+        }
+    }
+  if (!TryEnterCriticalSection (&mutex->lock))
+    return EBUSY;
+  return 0;
+}
+
+int
+glwthread_mutex_unlock (glwthread_mutex_t *mutex)
+{
+  if (!mutex->guard.done)
+    return EINVAL;
+  LeaveCriticalSection (&mutex->lock);
+  return 0;
+}
+
+int
+glwthread_mutex_destroy (glwthread_mutex_t *mutex)
+{
+  if (!mutex->guard.done)
+    return EINVAL;
+  DeleteCriticalSection (&mutex->lock);
+  mutex->guard.done = 0;
+  return 0;
+}