tests: Move busy loop to test support

Update #3056.

cpukit/libmisc/Makefile.am

@@ -174,6 +174,7 @@ libstringto_a_SOURCES = stringto/stringtodouble.c stringto/stringtofloat.c \
 noinst_LIBRARIES += libtestsupport.a
 libtestsupport_a_SOURCES =
 libtestsupport_a_SOURCES += testsupport/testbeginend.c
+libtestsupport_a_SOURCES += testsupport/testbusy.c
 libtestsupport_a_SOURCES += testsupport/testextension.c
 libtestsupport_a_SOURCES += testsupport/testparallel.c
 

cpukit/libmisc/testsupport/test.h

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2014, 2016 embedded brains GmbH.  All rights reserved.
+ * Copyright (c) 2014, 2017 embedded brains GmbH.  All rights reserved.
  *
  *  embedded brains GmbH
  *  Dornierstr. 4
@@ -260,6 +260,22 @@ void rtems_test_parallel(
   size_t job_count
 );
 
+/**
+ * @brief Performs a busy loop with the specified iteration count.
+ *
+ * This function is optimized to not perform memory accesses and should have a
+ * small jitter.
+ *
+ * @param[in] count The iteration count.
+ */
+void rtems_test_busy(uint_fast32_t count);
+
+/**
+ * @brief Returns a count value for rtems_test_busy() which yields roughly a
+ * duration of one clock tick.
+ */
+uint_fast32_t rtems_test_get_one_tick_busy_count(void);
+
 /** @} */
 
 #ifdef __cplusplus

cpukit/libmisc/testsupport/testbusy.c

@@ -0,0 +1,107 @@
+/*
+ * Copyright (c) 2014, 2017 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.
+ */
+
+
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#endif
+
+#include <rtems/test.h>
+#include <rtems.h>
+
+static uint_fast32_t estimate_busy_loop_maximum( void )
+{
+  uint_fast32_t units = 0;
+  uint_fast32_t initial = rtems_clock_get_ticks_since_boot();
+
+  while ( initial == rtems_clock_get_ticks_since_boot() ) {
+    ++units;
+  }
+
+  return units;
+}
+
+static uint_fast32_t wait_for_tick_change( void )
+{
+  uint_fast32_t initial = rtems_clock_get_ticks_since_boot();
+  uint_fast32_t now;
+
+  do {
+    now = rtems_clock_get_ticks_since_boot();
+  } while ( now == initial );
+
+  return now;
+}
+
+/*
+ * It is important that we use actually use the same rtems_test_busy() function
+ * at the various places, since otherwise the obtained maximum value might be
+ * wrong.  So, the compiler must not inline this function.
+ */
+RTEMS_NO_INLINE void rtems_test_busy( uint_fast32_t count )
+{
+  uint_fast32_t i = 0;
+
+  do {
+    __asm__ volatile ("");
+    ++i;
+  } while ( i < count );
+}
+
+uint_fast32_t rtems_test_get_one_tick_busy_count( void )
+{
+  uint_fast32_t last;
+  uint_fast32_t now;
+  uint_fast32_t a;
+  uint_fast32_t b;
+  uint_fast32_t m;
+
+  /* Choose a lower bound */
+  a = 1;
+
+  /* Estimate an upper bound */
+
+  wait_for_tick_change();
+  b = 2 * estimate_busy_loop_maximum();
+
+  while ( true ) {
+    last = wait_for_tick_change();
+    rtems_test_busy( b );
+    now = rtems_clock_get_ticks_since_boot();
+
+    if ( now != last ) {
+      break;
+    }
+
+    b *= 2;
+    last = now;
+  }
+
+  /* Find a good value */
+  do {
+    m = ( a + b ) / 2;
+
+    last = wait_for_tick_change();
+    rtems_test_busy( m );
+    now = rtems_clock_get_ticks_since_boot();
+
+    if ( now != last ) {
+      b = m;
+    } else {
+      a = m;
+    }
+  } while ( b - a > 1 );
+
+  return m;
+}

testsuites/sptests/spintrcritical_support/intrcritical.c

@@ -17,9 +17,9 @@
 #define INTERRUPT_CRITICAL_NAME rtems_build_name( 'I', 'C', 'R', 'I' )
 
 typedef struct {
-  rtems_interval minimum;
-  rtems_interval maximum;
-  rtems_interval maximum_current;
+  uint_fast32_t minimum;
+  uint_fast32_t maximum;
+  uint_fast32_t maximum_current;
   rtems_timer_service_routine_entry tsr;
   rtems_id timer;
   uint64_t t0;
@@ -28,19 +28,7 @@ typedef struct {
 
 static interrupt_critical_control interrupt_critical;
 
-static rtems_interval estimate_busy_loop_maximum( void )
-{
-  rtems_interval units = 0;
-  rtems_interval initial = rtems_clock_get_ticks_since_boot();
-
-  while ( initial == rtems_clock_get_ticks_since_boot() ) {
-    ++units;
-  }
-
-  return units;
-}
-
-static rtems_interval wait_for_tick_change( void )
+static void wait_for_tick_change( void )
 {
   rtems_interval initial = rtems_clock_get_ticks_since_boot();
   rtems_interval now;
@@ -48,75 +36,11 @@ static rtems_interval wait_for_tick_change( void )
   do {
     now = rtems_clock_get_ticks_since_boot();
   } while ( now == initial );
-
-  return now;
-}
-
-/*
- * It is important that we use actually use the same busy() function at the
- * various places, since otherwise the obtained maximum value might be wrong.
- * So the compiler must not inline this function.
- */
-static __attribute__( ( noinline ) ) void busy( rtems_interval max )
-{
-  rtems_interval i = 0;
-
-  do {
-    __asm__ volatile ("");
-    ++i;
-  } while ( i < max );
-}
-
-static rtems_interval get_one_tick_busy_value( void )
-{
-  rtems_interval last;
-  rtems_interval now;
-  rtems_interval a;
-  rtems_interval b;
-  rtems_interval m;
-
-  /* Choose a lower bound */
-  a = 1;
-
-  /* Estimate an upper bound */
-
-  wait_for_tick_change();
-  b = 2 * estimate_busy_loop_maximum();
-
-  while ( true ) {
-    last = wait_for_tick_change();
-    busy( b );
-    now = rtems_clock_get_ticks_since_boot();
-
-    if ( now != last ) {
-      break;
-    }
-
-    b *= 2;
-    last = now;
-  }
-
-  /* Find a good value */
-  do {
-    m = ( a + b ) / 2;
-
-    last = wait_for_tick_change();
-    busy( m );
-    now = rtems_clock_get_ticks_since_boot();
-
-    if ( now != last ) {
-      b = m;
-    } else {
-      a = m;
-    }
-  } while ( b - a > 1 );
-
-  return m;
 }
 
 static bool interrupt_critical_busy_wait( void )
 {
-  rtems_interval max = interrupt_critical.maximum_current;
+  uint_fast32_t max = interrupt_critical.maximum_current;
   bool reset = max <= interrupt_critical.minimum;
 
   if ( reset ) {
@@ -125,7 +49,7 @@ static bool interrupt_critical_busy_wait( void )
     interrupt_critical.maximum_current = max - 1;
   }
 
-  busy( max );
+  rtems_test_busy( max );
 
   return reset;
 }
@@ -134,7 +58,7 @@ void interrupt_critical_section_test_support_initialize(
   rtems_timer_service_routine_entry tsr
 )
 {
-  rtems_interval m;
+  uint_fast32_t m;
 
   interrupt_critical.tsr = tsr;
 
@@ -146,7 +70,7 @@ void interrupt_critical_section_test_support_initialize(
     rtems_test_assert( sc == RTEMS_SUCCESSFUL );
   }
 
-  m = get_one_tick_busy_value();
+  m = rtems_test_get_one_tick_busy_count();
 
   interrupt_critical.minimum = 0;
   interrupt_critical.maximum = m;
@@ -197,7 +121,7 @@ bool interrupt_critical_section_test(
   rtems_status_code sc;
   rtems_id id;
   uint64_t delta;
-  rtems_interval busy_delta;
+  uint_fast32_t busy_delta;
   int retries = 3;
 
   interrupt_critical_section_test_support_initialize( tsr );
@@ -222,7 +146,7 @@ bool interrupt_critical_section_test(
   /* Update minimum */
 
   delta = interrupt_critical.t1 - interrupt_critical.t0;
-  busy_delta = (rtems_interval)
+  busy_delta = (uint_fast32_t)
     ( ( interrupt_critical.maximum * ( 2 * delta ) )
       / rtems_configuration_get_nanoseconds_per_tick() );