| /* |
| * Copyright (c) 2016, The OpenThread Authors. |
| * All rights reserved. |
| * |
| * Redistribution and use in source and binary forms, with or without |
| * modification, are permitted provided that the following conditions are met: |
| * 1. Redistributions of source code must retain the above copyright |
| * notice, this list of conditions and the following disclaimer. |
| * 2. Redistributions in binary form must reproduce the above copyright |
| * notice, this list of conditions and the following disclaimer in the |
| * documentation and/or other materials provided with the distribution. |
| * 3. Neither the name of the copyright holder nor the |
| * names of its contributors may be used to endorse or promote products |
| * derived from this software without specific prior written permission. |
| * |
| * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" |
| * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE |
| * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE |
| * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE |
| * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR |
| * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF |
| * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS |
| * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN |
| * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) |
| * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE |
| * POSSIBILITY OF SUCH DAMAGE. |
| */ |
| |
| /** |
| * @file |
| * This file implements a multiplexed timer service on top of the alarm abstraction. |
| */ |
| |
| #define WPP_NAME "timer.tmh" |
| |
| #include <openthread/config.h> |
| |
| #include "timer.hpp" |
| |
| #include <openthread/platform/alarm.h> |
| |
| #include "openthread-instance.h" |
| #include "common/code_utils.hpp" |
| #include "common/debug.hpp" |
| #include "common/logging.hpp" |
| #include "net/ip6.hpp" |
| |
| namespace ot { |
| |
| TimerScheduler::TimerScheduler(void): |
| mHead(NULL) |
| { |
| } |
| |
| void TimerScheduler::Add(Timer &aTimer) |
| { |
| Remove(aTimer); |
| |
| if (mHead == NULL) |
| { |
| mHead = &aTimer; |
| aTimer.mNext = NULL; |
| SetAlarm(); |
| } |
| else |
| { |
| Timer *prev = NULL; |
| Timer *cur; |
| |
| for (cur = mHead; cur; cur = cur->mNext) |
| { |
| if (aTimer.DoesFireBefore(*cur)) |
| { |
| if (prev) |
| { |
| aTimer.mNext = cur; |
| prev->mNext = &aTimer; |
| } |
| else |
| { |
| aTimer.mNext = mHead; |
| mHead = &aTimer; |
| SetAlarm(); |
| } |
| |
| break; |
| } |
| |
| prev = cur; |
| } |
| |
| if (cur == NULL) |
| { |
| prev->mNext = &aTimer; |
| aTimer.mNext = NULL; |
| } |
| } |
| } |
| |
| void TimerScheduler::Remove(Timer &aTimer) |
| { |
| VerifyOrExit(aTimer.mNext != &aTimer); |
| |
| if (mHead == &aTimer) |
| { |
| mHead = aTimer.mNext; |
| SetAlarm(); |
| } |
| else |
| { |
| for (Timer *cur = mHead; cur; cur = cur->mNext) |
| { |
| if (cur->mNext == &aTimer) |
| { |
| cur->mNext = aTimer.mNext; |
| break; |
| } |
| } |
| } |
| |
| aTimer.mNext = &aTimer; |
| |
| exit: |
| return; |
| } |
| |
| void TimerScheduler::SetAlarm(void) |
| { |
| if (mHead == NULL) |
| { |
| otPlatAlarmStop(GetIp6()->GetInstance()); |
| } |
| else |
| { |
| uint32_t now = otPlatAlarmGetNow(); |
| uint32_t remaining = IsStrictlyBefore(now, mHead->mFireTime) ? (mHead->mFireTime - now) : 0; |
| |
| otPlatAlarmStartAt(GetIp6()->GetInstance(), now, remaining); |
| } |
| } |
| |
| extern "C" void otPlatAlarmFired(otInstance *aInstance) |
| { |
| otLogFuncEntry(); |
| aInstance->mIp6.mTimerScheduler.ProcessTimers(); |
| otLogFuncExit(); |
| } |
| |
| void TimerScheduler::ProcessTimers(void) |
| { |
| Timer *timer = mHead; |
| |
| if (timer) |
| { |
| if (!IsStrictlyBefore(otPlatAlarmGetNow(), timer->mFireTime)) |
| { |
| Remove(*timer); |
| timer->Fired(); |
| } |
| else |
| { |
| SetAlarm(); |
| } |
| } |
| else |
| { |
| SetAlarm(); |
| } |
| } |
| |
| Ip6::Ip6 *TimerScheduler::GetIp6(void) |
| { |
| return Ip6::Ip6FromTimerScheduler(this); |
| } |
| |
| bool TimerScheduler::IsStrictlyBefore(uint32_t aTimeA, uint32_t aTimeB) |
| { |
| uint32_t diff = aTimeA - aTimeB; |
| |
| // Three cases: |
| // 1) aTimeA is before aTimeB => Difference is negative (last bit of difference is set) => Returning true. |
| // 2) aTimeA is same as aTimeB => Difference is zero (last bit of difference is clear) => Returning false. |
| // 3) aTimeA is after aTimeB => Difference is positive (last bit of difference is clear) => Returning false. |
| |
| return ((diff & (1UL << 31)) != 0); |
| } |
| |
| bool Timer::DoesFireBefore(const Timer &aSecondTimer) |
| { |
| bool retval; |
| uint32_t now = GetNow(); |
| bool isBeforeNow = TimerScheduler::IsStrictlyBefore(GetFireTime(), now); |
| |
| // Check if one timer is before `now` and the other one is not. |
| if (TimerScheduler::IsStrictlyBefore(aSecondTimer.GetFireTime(), now) != isBeforeNow) |
| { |
| // One timer is before `now` and the other one is not, so if this timer's fire time is before `now` then |
| // the second fire time would be after `now` and this timer would fire before the second timer. |
| |
| retval = isBeforeNow; |
| } |
| else |
| { |
| // Both timers are before `now` or both are after `now`. Either way the difference is guaranteed to be less |
| // than `kMaxDt` so we can safely compare the fire times directly. |
| |
| retval = TimerScheduler::IsStrictlyBefore(GetFireTime(), aSecondTimer.GetFireTime()); |
| } |
| |
| return retval; |
| } |
| |
| } // namespace ot |