score: Add libatomic support

Close #2695.

1 files changed, 79 insertions, 0 deletions

diff --git a/cpukit/score/src/libatomic.c b/cpukit/score/src/libatomic.c
new file mode 100644
index 0000000000..bfa3e6fb25
--- /dev/null
+++ b/cpukit/score/src/libatomic.c
@@ -0,0 +1,79 @@
+/*
+ * Copyright (c) 2016 embedded brains GmbH.  All rights reserved.
+ *
+ *  embedded brains GmbH
+ *  Dornierstr. 4
+ *  82178 Puchheim
+ *  Germany
+ *  <rtems@embedded-brains.de>
+ *
+ * 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.
+ */
+
+#if HAVE_CONFIG_H
+#include "config.h"
+#endif
+
+#include <machine/_libatomic.h>
+
+#include <rtems/score/apimutex.h>
+#include <rtems/score/atomic.h>
+#include <rtems/score/isrlevel.h>
+
+#if defined(RTEMS_SMP)
+/*
+ * For real SMP targets this is not useful.  The main purpose is support for
+ * testing on simulators like SIS.
+ */
+static Atomic_Flag _Libatomic_The_one_lock = ATOMIC_INITIALIZER_FLAG;
+#endif
+
+__uint32_t _Libatomic_Protect_start( void *ptr )
+{
+  ISR_Level isr_level;
+
+  (void) ptr;
+  _ISR_Local_disable( isr_level );
+
+#if defined(RTEMS_SMP)
+  while (
+    _Atomic_Flag_test_and_set( &_Libatomic_The_one_lock, ATOMIC_ORDER_SEQ_CST )
+  ) {
+    /* Next try.  Yes, a TAS spin lock implementation is stupid. */
+  }
+#endif
+
+  return isr_level;
+}
+
+void _Libatomic_Protect_end( void *ptr, __uint32_t isr_level )
+{
+  (void) ptr;
+
+#if defined(RTEMS_SMP)
+  _Atomic_Flag_clear( &_Libatomic_The_one_lock, ATOMIC_ORDER_SEQ_CST );
+#endif
+
+  _ISR_Local_enable( isr_level );
+}
+
+/*
+ * FIXME: The once lock should be only a temporary solution. We need a
+ * dedicated internal mutex for this.
+ */
+
+void _Libatomic_Lock_n( void *ptr, __size_t n )
+{
+  (void) ptr;
+  (void) n;
+  _Once_Lock();
+}
+
+void _Libatomic_Unlock_n( void *ptr, __size_t n )
+{
+  (void) ptr;
+  (void) n;
+  _Once_Unlock();
+}