[PATCH] libtest: Improve T_now_tick()

[Sebastian Huber]

The T_now_tick() is a fall back time measurement using the CPU counter
in case no Clock Driver is configured.  Some CPU counter may overflow
during the test execution.  Accumulate the elapsed time to reduce the
chance of CPU counter overflows.
---
 cpukit/libtest/t-test-time.c | 45 ++++++++++++++++++++++++++++++++++++
 1 file changed, 45 insertions(+)

diff --git a/cpukit/libtest/t-test-time.c b/cpukit/libtest/t-test-time.c
index 156ceaad1f..c6a43acfc5 100644
--- a/cpukit/libtest/t-test-time.c
+++ b/cpukit/libtest/t-test-time.c
@@ -35,6 +35,7 @@
 #include <time.h>
 
 #ifdef __rtems__
+#include <rtems.h>
 #include <rtems/counter.h>
 #include <rtems/score/timecounter.h>
 #endif
@@ -231,8 +232,52 @@ T_now_dummy(void)
 	    memory_order_relaxed);
 }
 
+#ifndef __rtems__
 T_time
 T_now_tick(void)
 {
 	return T_ticks_to_time(T_tick());
 }
+#else /* __rtems__ */
+#if defined(RTEMS_SMP)
+static rtems_interrupt_lock T_time_lock =
+  RTEMS_INTERRUPT_LOCK_INITIALIZER("Test Time Lock");
+#endif
+
+static T_ticks T_tick_last;
+
+static T_time T_tick_time;
+
+static bool T_tick_initialized;
+
+T_time
+T_now_tick(void)
+{
+	rtems_interrupt_lock_context lock_context;
+	T_ticks ticks;
+	T_time now;
+
+	ticks = T_tick();
+
+	rtems_interrupt_lock_acquire(&T_time_lock, &lock_context);
+
+	if (T_tick_initialized) {
+		T_ticks last;
+
+		last = T_tick_last;
+		T_tick_last = ticks;
+
+		now = T_tick_time;
+		now += T_ticks_to_time(ticks - last);
+		T_tick_time = now;
+	} else {
+		T_tick_initialized = true;
+		T_tick_last = ticks;
+		now = 0;
+	}
+
+	rtems_interrupt_lock_release(&T_time_lock, &lock_context);
+
+	return now;
+}
+#endif /* __rtems__ */
-- 
2.31.1