score: Add CPU counter support

Add a CPU counter interface to allow access to a free-running counter.
It is useful to measure short time intervals.  This can be used for
example to enable profiling of critical low-level functions.

Add two busy wait functions rtems_counter_delay_ticks() and
rtems_counter_delay_nanoseconds() implemented via the CPU counter.

1 files changed, 27 insertions, 0 deletions

diff --git a/cpukit/score/cpu/no_cpu/cpucounterread.c b/cpukit/score/cpu/no_cpu/cpucounterread.c
new file mode 100644
index 0000000000..0a09376b63
--- /dev/null
+++ b/cpukit/score/cpu/no_cpu/cpucounterread.c
@@ -0,0 +1,27 @@
+/*
+ * Copyright (c) 2014 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.com/license/LICENSE.
+ */
+
+#include <rtems/score/cpu.h>
+
+CPU_Counter_ticks _CPU_Counter_read( void )
+{
+  static CPU_Counter_ticks counter;
+
+  CPU_Counter_ticks snapshot;
+
+  snapshot = counter;
+  counter = snapshot + 1;
+
+  return snapshot;
+}