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, 35 insertions, 0 deletions

diff --git a/cpukit/sapi/src/delayticks.c b/cpukit/sapi/src/delayticks.c
new file mode 100644
index 0000000000..45198adecb
--- /dev/null
+++ b/cpukit/sapi/src/delayticks.c
@@ -0,0 +1,35 @@
+/*
+ * 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.
+ */
+
+#ifdef HAVE_CONFIG_H
+  #include "config.h"
+#endif
+
+#include <rtems/counter.h>
+
+void rtems_counter_delay_ticks( rtems_counter_ticks ticks )
+{
+  rtems_counter_ticks a = rtems_counter_read();
+  rtems_counter_ticks delta = 0;
+
+  do {
+    rtems_counter_ticks b;
+
+    ticks -= delta;
+
+    b = rtems_counter_read();
+    delta = rtems_counter_difference( b, a );
+    a = b;
+  } while ( ticks > delta );
+}