1 files changed, 56 insertions, 0 deletions
diff --git a/cpukit/score/src/once.c b/cpukit/score/src/once.c
new file mode 100644
index 0000000000..60ae7a78c4
--- /dev/null
+++ b/cpukit/score/src/once.c
@@ -0,0 +1,56 @@
+/*
+ *  COPYRIGHT (c) 1989-1999.
+ *  On-Line Applications Research Corporation (OAR).
+ *
+ *  The license and distribution terms for this file may be
+ *  found in the file LICENSE in this distribution or at
+ *  http://www.rtems.org/license/LICENSE.
+ */
+
+#ifdef HAVE_CONFIG_H
+  #include "config.h"
+#endif
+
+#include <rtems/score/onceimpl.h>
+#include <rtems/score/apimutex.h>
+
+#include <errno.h>
+
+#define ONCE_STATE_NOT_RUN  0
+#define ONCE_STATE_RUNNING  1
+#define ONCE_STATE_COMPLETE 2
+
+int _Once( int *once_state, void ( *init_routine )( void ) )
+{
+  int eno = 0;
+
+  if ( *once_state != ONCE_STATE_COMPLETE ) {
+    _Once_Lock();
+
+    /*
+     * Getting to here means the once_control is locked so we have:
+     *  1. The init has not run and the state is ONCE_STATE_NOT_RUN.
+     *  2. The init has finished and the state is ONCE_STATE_COMPLETE (already
+     *     caught by the previous if).
+     *  3. The init is being run by this thread and the state
+     *     ONCE_STATE_RUNNING so we are nesting. This is an error.
+     */
+
+    switch ( *once_state ) {
+      case ONCE_STATE_NOT_RUN:
+        *once_state = ONCE_STATE_RUNNING;
+        ( *init_routine )();
+        *once_state = ONCE_STATE_COMPLETE;
+        break;
+      case ONCE_STATE_RUNNING:
+        eno = EINVAL;
+        break;
+      default:
+        break;
+    }
+
+    _Once_Unlock();
+  }
+
+  return eno;
+}