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+/*
+ * pthread_once.c
+ *
+ * Description:
+ * This translation unit implements miscellaneous thread functions.
+ *
+ * --------------------------------------------------------------------------
+ *
+ * Pthreads-win32 - POSIX Threads Library for Win32
+ * Copyright(C) 1998 John E. Bossom
+ * Copyright(C) 1999,2002 Pthreads-win32 contributors
+ *
+ * Contact Email: rpj@ise.canberra.edu.au
+ *
+ * The current list of contributors is contained
+ * in the file CONTRIBUTORS included with the source
+ * code distribution. The list can also be seen at the
+ * following World Wide Web location:
+ * http://sources.redhat.com/pthreads-win32/contributors.html
+ *
+ * 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 2 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 in the file COPYING.LIB;
+ * if not, write to the Free Software Foundation, Inc.,
+ * 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
+ */
+
+#include "pthread.h"
+#include "implement.h"
+
+
+int
+pthread_once (
+ pthread_once_t * once_control,
+ void (*init_routine) (void)
+)
+ /*
+ * ------------------------------------------------------
+ * DOCPUBLIC
+ * If any thread in a process with a once_control parameter
+ * makes a call to pthread_once(), the first call will summon
+ * the init_routine(), but subsequent calls will not. The
+ * once_control parameter determines whether the associated
+ * initialization routine has been called. The init_routine()
+ * is complete upon return of pthread_once().
+ * This function guarantees that one and only one thread
+ * executes the initialization routine, init_routine when
+ * access is controlled by the pthread_once_t control
+ * key.
+ *
+ * PARAMETERS
+ * once_control
+ * pointer to an instance of pthread_once_t
+ *
+ * init_routine
+ * pointer to an initialization routine
+ *
+ *
+ * DESCRIPTION
+ * See above.
+ *
+ * RESULTS
+ * 0 success,
+ * EINVAL once_control or init_routine is NULL
+ *
+ * ------------------------------------------------------
+ */
+{
+ int result;
+
+ if (once_control == NULL || init_routine == NULL)
+ {
+
+ result = EINVAL;
+ goto FAIL0;
+
+ }
+ else
+ {
+ result = 0;
+ }
+
+ if (!once_control->done)
+ {
+ if (InterlockedIncrement (&(once_control->started)) == 0)
+ {
+ /*
+ * First thread to increment the started variable
+ */
+ (*init_routine) ();
+ once_control->done = TRUE;
+
+ }
+ else
+ {
+ /*
+ * Block until other thread finishes executing the onceRoutine
+ */
+ while (!(once_control->done))
+ {
+ /*
+ * The following gives up CPU cycles without pausing
+ * unnecessarily
+ */
+ Sleep (0);
+ }
+ }
+ }
+
+ /*
+ * Fall through Intentionally
+ */
+
+ /*
+ * ------------
+ * Failure Code
+ * ------------
+ */
+FAIL0:
+ return (result);
+
+} /* pthread_once */