genode/repos/base/src/timer/periodic/time_source.cc

53 lines
1.2 KiB
C++

/*
* \brief Time source that uses sleeping by the means of the kernel
* \author Norman Feske
* \author Martin Stein
* \date 2009-06-16
*/
/*
* Copyright (C) 2009-2017 Genode Labs GmbH
*
* This file is part of the Genode OS framework, which is distributed
* under the terms of the GNU Affero General Public License version 3.
*/
/* local includes */
#include <time_source.h>
using namespace Genode;
void Timer::Time_source::schedule_timeout(Microseconds duration,
Timeout_handler &handler)
{
Genode::Lock::Guard lock_guard(_lock);
Threaded_time_source::handler(handler);
_next_timeout_us = duration.value;
}
void Timer::Time_source::_wait_for_irq()
{
enum { SLEEP_GRANULARITY_US = 1000 };
uint64_t last_time_us = curr_time().trunc_to_plain_us().value;
_lock.lock();
while (_next_timeout_us > 0) {
_lock.unlock();
try { _usleep(SLEEP_GRANULARITY_US); }
catch (Blocking_canceled) { }
uint64_t curr_time_us = curr_time().trunc_to_plain_us().value;
uint64_t sleep_duration_us = curr_time_us - last_time_us;
last_time_us = curr_time_us;
_lock.lock();
if (_next_timeout_us >= sleep_duration_us)
_next_timeout_us -= sleep_duration_us;
else
break;
}
_lock.unlock();
}