forked from Imagelibrary/rtems
24bf11eca1
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.
113 lines
2.5 KiB
C
113 lines
2.5 KiB
C
/*
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* Copyright (c) 2014 embedded brains GmbH. All rights reserved.
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*
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* embedded brains GmbH
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* Dornierstr. 4
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* 82178 Puchheim
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* Germany
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* <rtems@embedded-brains.de>
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*
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* The license and distribution terms for this file may be
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* found in the file LICENSE in this distribution or at
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* http://www.rtems.com/license/LICENSE.
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*/
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#ifdef HAVE_CONFIG_H
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#include "config.h"
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#endif
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#include <stdio.h>
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#include <inttypes.h>
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#include <rtems.h>
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#include <rtems/counter.h>
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#define TESTS_USE_PRINTF
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#include "tmacros.h"
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#define NS_PER_TICK 1000000
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static rtems_interval sync_with_clock_tick(void)
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{
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rtems_interval start = rtems_clock_get_ticks_since_boot();
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rtems_interval current;
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do {
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current = rtems_clock_get_ticks_since_boot();
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} while (current == start);
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return current;
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}
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static void test_converter(void)
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{
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CPU_Counter_ticks frequency = rtems_counter_nanoseconds_to_ticks(1000000000);
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uint64_t ns = rtems_counter_ticks_to_nanoseconds(frequency);
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printf("CPU counter frequency: %" PRIu32 "Hz\n", frequency);
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printf("nanoseconds for frequency count ticks: %" PRIu64 "\n", ns);
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rtems_test_assert(ns == 1000000000);
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}
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static void test_delay_nanoseconds(void)
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{
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rtems_counter_ticks start;
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rtems_counter_ticks end;
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rtems_counter_ticks delta;
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double ns_per_tick = NS_PER_TICK;
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double ns_delta;
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rtems_interval tick;
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int n = 10;
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int i;
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printf("test delay nanoseconds (%i times)\n", n);
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for (i = 0; i < n; ++i) {
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tick = sync_with_clock_tick();
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start = rtems_counter_read();
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rtems_counter_delay_nanoseconds(NS_PER_TICK);
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end = rtems_counter_read();
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rtems_test_assert(tick < rtems_clock_get_ticks_since_boot());
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delta = rtems_counter_difference(end, start);
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ns_delta = rtems_counter_ticks_to_nanoseconds(delta);
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rtems_test_assert(ns_delta >= ns_per_tick);
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printf(
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"busy wait relative to clock tick: %f\n",
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(ns_delta - ns_per_tick) / ns_per_tick
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);
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}
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}
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static void Init(rtems_task_argument arg)
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{
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puts("\n\n*** TEST SPCPUCOUNTER 1 ***");
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test_converter();
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test_delay_nanoseconds();
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puts("*** END OF TEST SPCPUCOUNTER 1 ***");
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rtems_test_exit(0);
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}
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#define CONFIGURE_APPLICATION_NEEDS_CLOCK_DRIVER
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#define CONFIGURE_APPLICATION_NEEDS_CONSOLE_DRIVER
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#define CONFIGURE_MICROSECONDS_PER_TICK (NS_PER_TICK / 1000)
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#define CONFIGURE_MAXIMUM_TASKS 1
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#define CONFIGURE_INIT_TASK_ATTRIBUTES RTEMS_FLOATING_POINT
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#define CONFIGURE_RTEMS_INIT_TASKS_TABLE
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#define CONFIGURE_INIT
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#include <rtems/confdefs.h>
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