/core/src/aos_sssp.c - AMiRo-OS - Research for Cognitive Interaction

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       /*
       AMiRo-OS is an operating system designed for the Autonomous Mini Robot (AMiRo) platform.
       Copyright (C) 2016..2019  Thomas Schöpping et al.
       This program is free software: you can redistribute it and/or modify
       it under the terms of the GNU General Public License as published by
       the Free Software Foundation, either version 3 of the License, or
       (at your option) any later version.
       This program is distributed in the hope that it will be useful,
       but WITHOUT ANY WARRANTY; without even the implied warranty of
       MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
       GNU General Public License for more details.
       You should have received a copy of the GNU General Public License
       along with this program.  If not, see <http://www.gnu.org/licenses/>.
       */
       /**
        * @file    aos_sssp.c
        * @brief   SSSP related code.
+       *
        * @addtogroup aos_sssp
        * @{
        */
       #include <amiroos.h>
       #if (AMIROOS_CFG_SSSP_ENABLE == true) || defined(__DOXYGEN__)
       /******************************************************************************/
       /* LOCAL DEFINITIONS                                                          */
       /******************************************************************************/
       #if ((AMIROOS_CFG_SSSP_MASTER != true) && (AMIROOS_CFG_PROFILE == true)) || defined(__DOXYGEN__)
       /**
        * @brief   Weighting factor for smoothing the @p _syncskew value.
        */
       #define SYNCSKEW_SMOOTHFACTOR                   (0.1f / AOS_SYSTEM_TIME_RESOLUTION)
       #endif /* (AMIROOS_CFG_SSSP_MASTER != true) && (AMIROOS_CFG_PROFILE == true) */
       /******************************************************************************/
       /* EXPORTED VARIABLES                                                         */
       /******************************************************************************/
       /******************************************************************************/
       /* LOCAL TYPES                                                                */
       /******************************************************************************/
       /******************************************************************************/
       /* LOCAL VARIABLES                                                            */
       /******************************************************************************/
       /**
        * @brief   Pointer to the system uptime.
        */
       static aos_timestamp_t* _uptime;
       #if (AMIROOS_CFG_SSSP_MASTER == true) || defined(__DOXYGEN__)
       /**
        * @brief   Timer to drive the S signal for system wide time synchronization during operation phase.
        */
       static virtual_timer_t _synctimer;
       /**
        * @brief   Last uptime of system wide time synchronization.
        */
       static aos_timestamp_t _synctime;
       #endif /* (AMIROOS_CFG_SSSP_MASTER == true) */
       #if ((AMIROOS_CFG_SSSP_MASTER != true) && (AMIROOS_CFG_PROFILE == true)) || defined(__DOXYGEN__)
       /**
        * @brief   Offset between local clock and system wide synchronization signal.
        */
       static float _syncskew;
       #endif /* (AMIROOS_CFG_SSSP_MASTER != true) && (AMIROOS_CFG_PROFILE == true) */
       /**
        * @brief   A timer event based delays.
        */
       static virtual_timer_t _delayTimer;
       /**
        * @brief   Event source for the delay timer.
        */
       static event_source_t _eventSourceDelay;
       /**
        * @brief   Event listener for the delay event.
        */
       static event_listener_t _eventListenerDelay;
       /******************************************************************************/
       /* LOCAL FUNCTIONS                                                            */
       /******************************************************************************/
       #if (AMIROOS_CFG_SSSP_MASTER != true) || defined(__DOXYGEN__)
       /**
        * @brief   Callback function for the Sync signal interrupt.
+       *
        * @param[in] args   Pointer to the GPIO line identifier.
        */
       static void _gpioCallbackSSignal(void *args)
+      {
         aosDbgCheck((args != NULL) && (*((ioline_t*)args) != PAL_NOLINE) && (PAL_PAD(*((ioline_t*)args)) < sizeof(eventflags_t) * 8));
         apalControlGpioState_t s;
         aos_timestamp_t t;
         chSysLockFromISR();
         // if the system is in operation phase
         if (aos.sssp.stage == AOS_SSSP_STAGE_OPERATION) {
           // read signal S
           apalControlGpioGet(&moduleSsspGpioS, &s);
           // if S was toggled from on to off
           if (s == APAL_GPIO_OFF) {
             // get current uptime
             aosSysGetUptimeX(&t);
             // align the uptime with the synchronization period
             t %= AMIROOS_CFG_SSSP_SYSSYNCPERIOD;
             if (t < AMIROOS_CFG_SSSP_SYSSYNCPERIOD / 2) {
               *_uptime -= t;
       #if (AMIROOS_CFG_PROFILE == true)
               _syncskew = ((1.0f - SYNCSKEW_SMOOTHFACTOR) * _syncskew) + (SYNCSKEW_SMOOTHFACTOR * t);
       #endif /* (AMIROOS_CFG_PROFILE == true) */
             } else {
               t = AMIROOS_CFG_SSSP_SYSSYNCPERIOD - t;
               *_uptime += t;
       #if (AMIROOS_CFG_PROFILE == true)
               _syncskew = ((1.0f - SYNCSKEW_SMOOTHFACTOR) * _syncskew) - (SYNCSKEW_SMOOTHFACTOR * t);
       #endif /* (AMIROOS_CFG_PROFILE == true) */
+            }
+          }
+        }
         // broadcast event
         chEvtBroadcastFlagsI(&aos.events.gpio, AOS_GPIOEVENT_FLAG(PAL_PAD(*((ioline_t*)args))));
         chSysUnlockFromISR();
         return;
+      }
       #endif /* (AMIROOS_CFG_SSSP_MASTER != true) */
       #if (AMIROOS_CFG_SSSP_MASTER == true) || defined (__DOXYGEN__)
       /**
        * @brief   Periodic system synchronization callback function.
        * @details Toggles the SYS_SYNC signal and reconfigures the system synchronization timer.
+       *
        * @param[in] par   Unused parameters.
        */
       static void _syncTimerCallback(void* par)
+      {
         (void)par;
         apalControlGpioState_t state;
         aos_timestamp_t uptime;
         chSysLockFromISR();
         // toggle and read signal S
         apalGpioToggle(moduleSsspGpioS.gpio);
         apalControlGpioGet(&moduleSsspGpioS, &state);
         // if S was toggled from off to on
         if (state == APAL_GPIO_ON) {
           // reconfigure the timer precisely, because the logically falling edge (next interrupt) snychronizes the system time
           _synctime += AMIROOS_CFG_SSSP_SYSSYNCPERIOD;
           aosSysGetUptimeX(&uptime);
           chVTSetI(&_synctimer, chTimeUS2I(_synctime - uptime), _syncTimerCallback, NULL);
+        }
         // if S was toggled from on to off
         else /* if (state == APAL_GPIO_OFF) */ {
           // reconfigure the timer (lazy)
           chVTSetI(&_synctimer, chTimeUS2I(AMIROOS_CFG_SSSP_SYSSYNCPERIOD / 2), _syncTimerCallback, NULL);
+        }
         chSysUnlockFromISR();
         return;
+      }
       /**
        * @brief   Start the timer that toggles S for synchronization of the system.
        * @note    Must be called from a locked context.
        */
       static inline void _syncTimerStartS(void)
+      {
         chDbgCheckClassS();
         // start synchronization timer
         // The first iteration of the timer is set to the next 'center' of a 'slice'.
         aos_timestamp_t t;
         aosSysGetUptimeX(&t);
         t = AMIROOS_CFG_SSSP_SYSSYNCPERIOD - (t % AMIROOS_CFG_SSSP_SYSSYNCPERIOD);
         chVTSetI(&_synctimer, chTimeUS2I((t > (AMIROOS_CFG_SSSP_SYSSYNCPERIOD / 2)) ? (t - (AMIROOS_CFG_SSSP_SYSSYNCPERIOD / 2)) : (t + (AMIROOS_CFG_SSSP_SYSSYNCPERIOD / 2))), _syncTimerCallback, NULL);
         return;
+      }
       #endif /* (AMIROOS_CFG_SSSP_MASTER == true) */
       /**
        * @brief   General callback function to be used for any local timers.
+       *
        * @param[in] par   A pointer to an @p event_source_t to be fired.
        */
       static void _timerCallback(void* par)
+      {
         aosDbgCheck(par != NULL);
         chSysLockFromISR();
         chEvtBroadcastI((event_source_t*)par);
         chSysUnlockFromISR();
         return;
+      }
       /**
        * @brief   Waits for the S signal to switch to the desired state.
+       *
        * @param[in]   listener      Pointer to the GPIO event listener to be used.
        * @param[in]   flags         Event flags to listen to by the event listener (indicating a S signal event).
        * @param[in]   signalstate   Desired state of the S signal ti be waited for.
        * @param[out]  received      Output variable to store the received event mask to.
+       *
        * @return  Status, indicating whether the expected event was received.
        */
       static inline aos_status_t _waitForS(event_listener_t* listener, eventflags_t flags, apalControlGpioState_t signalstate, eventmask_t* received)
+      {
         aosDbgCheck(listener != NULL);
         aosDbgCheck(flags != 0);
         aosDbgCheck(received != NULL);
         // wait for the next event (do not apply any filters in order not to miss any events)
         *received = chEvtWaitOne(ALL_EVENTS);
         // if the correct event was triggered
         if (*received == listener->events) {
           apalControlGpioState_t s;
           apalControlGpioGet(&moduleSsspGpioS, &s);
           // only check for the expected event
           if (flags & listener->flags && s == signalstate) {
             // unset the expected flags but keep any other ones
             listener->flags &= ~flags;
             return AOS_SUCCESS;
+          }
+        }
         return AOS_FAILURE;
+      }
       /**
        * @brief   Uses the local delay timer to setup a timed event and waits for it to fire.
+       *
        * @param[in]   dt          Delay time in microseconds to be set to the timer.
        * @param[in]   mask        Event mask to be used for the delay timer.
        * @param[in]   arm_timer   Flag to indicate whether the timer has to be armed yet (i.e. on first call of this function).
        * @param[out]  received    Output variable to store the received event mask to.
+       *
        * @return  Status, indicating whether the expected event (delay timer) was received.
        */
       static inline aos_status_t _delay(uint32_t dt, eventmask_t mask, bool arm_timer, eventmask_t* received)
+      {
         aosDbgCheck(dt != TIME_IMMEDIATE);
         aosDbgCheck(mask != 0);
         aosDbgCheck(received != NULL);
         // arm the delay timer once
         if (arm_timer) {
           chEvtRegisterMask(&_eventSourceDelay, &_eventListenerDelay, mask);
           chVTSet(&_delayTimer, chTimeUS2I(dt), _timerCallback, &_eventSourceDelay);
+        }
         // wait for any event to occur (do not apply any filters in order not to miss any events)
         *received = chEvtWaitOne(ALL_EVENTS);
         // if the timer event was received, cleanup
         if (*received & _eventListenerDelay.events) {
           chEvtUnregister(&_eventSourceDelay, &_eventListenerDelay);
           return AOS_SUCCESS;
+        }
         return AOS_FAILURE;
+      }
       /******************************************************************************/
       /* EXPORTED FUNCTIONS                                                         */
       /******************************************************************************/
       /**
        * @brief   Initialize all SSSP related data.
        */
       void aosSsspInit(aos_timestamp_t* system_uptime)
+      {
         aosDbgCheck(system_uptime != NULL);
         // local variables
         apalControlGpioState_t state;
       #if (AMIROOS_CFG_SSSP_STARTUP == true)
         // AMiRo-OS has to perform the basic initialization
         aos.sssp.stage = AOS_SSSP_STAGE_STARTUP_1_1;
       #else /* (AMIROOS_CFG_SSSP_STARTUP == true) */
         // basic initialization was already performed by a bootloader
         aos.sssp.stage = AOS_SSSP_STAGE_STARTUP_2_1;
       #endif /* (AMIROOS_CFG_SSSP_STARTUP == true) */
         // check all SSSP signals for correct state
         apalControlGpioGet(&moduleSsspGpioS, &state);
         aosDbgAssert(state == APAL_GPIO_ON);
         apalControlGpioGet(&moduleSsspGpioPD, &state);
         aosDbgAssert(state == APAL_GPIO_OFF);
       #if (AMIROOS_CFG_SSSP_MSI == true)
       #if (AMIROOS_CFG_SSSP_STACK_END != true)
         apalControlGpioGet(&moduleSsspGpioUP, &state);
         aosDbgAssert(state == APAL_GPIO_OFF);
       #endif /* (AMIROOS_CFG_SSSP_STACK_END != true) */
       #if (AMIROOS_CFG_SSSP_STACK_START != true)
         apalControlGpioGet(&moduleSsspGpioDN, &state);
         aosDbgAssert(state == APAL_GPIO_OFF);
       #endif /* (AMIROOS_CFG_SSSP_STACK_START != true) */
       #endif /* (AMIROOS_CFG_SSSP_MSI == true) */
       #if (AMIROOS_CFG_SSSP_MSI == true)
         // module ID is initialized as 'invalid'
         aos.sssp.moduleId = AOS_SSSP_MODULEID_INVALID;
       #endif /* (AMIROOS_CFG_SSSP_MSI == true) */
         // initialize static variables
         _uptime = system_uptime;
       #if (AMIROOS_CFG_SSSP_MASTER == true)
         chVTObjectInit(&_synctimer);
         _synctime = 0;
       #endif /* (AMIROOS_CFG_SSSP_MASTER == true) */
       #if (AMIROOS_CFG_SSSP_MASTER != true) && (AMIROOS_CFG_PROFILE == true)
         _syncskew = 0.0f;
       #endif /* (AMIROOS_CFG_SSSP_MASTER != true) && (AMIROOS_CFG_PROFILE == true) */
         chVTObjectInit(&_delayTimer);
         chEvtObjectInit(&_eventSourceDelay);
         // signal interrupt setup
         palSetLineCallback(moduleSsspGpioPD.gpio->line, aosSysGetStdGpioCallback(), &moduleSsspGpioPD.gpio->line);
         palEnableLineEvent(moduleSsspGpioPD.gpio->line, APAL2CH_EDGE(moduleSsspGpioPD.meta.edge));
       #if (AMIROOS_CFG_SSSP_MASTER == true)
         palSetLineCallback(moduleSsspGpioS.gpio->line, aosSysGetStdGpioCallback(), &moduleSsspGpioS.gpio->line);
       #else /* (AMIROOS_CFG_SSSP_MASTER == true) */
         palSetLineCallback(moduleSsspGpioS.gpio->line, _gpioCallbackSSignal, &moduleSsspGpioS.gpio->line);
       #endif /* (AMIROOS_CFG_SSSP_MASTER == true) */
         palEnableLineEvent(moduleSsspGpioS.gpio->line, APAL2CH_EDGE(moduleSsspGpioS.meta.edge));
       #if (AMIROOS_CFG_SSSP_MSI == true)
       #if (AMIROOS_CFG_SSSP_STACK_START != true)
         palSetLineCallback(moduleSsspGpioDN.gpio->line, aosSysGetStdGpioCallback(), &moduleSsspGpioDN.gpio->line);
         palEnableLineEvent(moduleSsspGpioDN.gpio->line, APAL2CH_EDGE(moduleSsspGpioDN.meta.edge));
       #endif /* (AMIROOS_CFG_SSSP_STACK_START != true) */
       #if (AMIROOS_CFG_SSSP_STACK_END != true)
         palSetLineCallback(moduleSsspGpioUP.gpio->line, aosSysGetStdGpioCallback(), &moduleSsspGpioUP.gpio->line);
         palEnableLineEvent(moduleSsspGpioUP.gpio->line, APAL2CH_EDGE(moduleSsspGpioUP.meta.edge));
       #endif /* (AMIROOS_CFG_SSSP_STACK_END != true) */
       #endif /* (AMIROOS_CFG_SSSP_MSI == true) */
         return;
+      }
       /**
        * @brief   Proceed to the next SSSP stage.
        * @note    Calling this function when in operation phase is invalid.
        *          The function aosSsspShutdownInit() must be used instead.
+       *
        * @param[in]   listener  An optional listener, in case the system has to wait for a specific event.
        * @param[in]   flags     The relevant flags to wait for (mandatory if a listener is given).
        * @param[in]   mask      If the stage transition involves a timer event (handled internally by this function),
        *                        the given input value of this parameter defines the mask to be used for that event.
        *                        In case a listener was specified, the according mask is retrieved from the listener but this parameter is still used as input for sanity checks.
        * @param[out]  received  Output variable to store the received event mask to.
+       *
        * @return  Status, indicating whether proceeding in the protocol was successful.
        */
       aos_status_t aosSsspProceed(event_listener_t* listener, eventflags_t flags, eventmask_t mask, eventmask_t* received)
+      {
         // local variables
       #pragma GCC diagnostic push
       #pragma GCC diagnostic ignored "-Wunused-but-set-variable"
         static aos_ssspstage_t laststage = AOS_SSSP_STAGE_UNDEFINED;
       #pragma GCC diagnostic pop
         aos_ssspstage_t nextstage = aos.sssp.stage;
         // behaviour depends on current SSSP stage of the system
         switch (aos.sssp.stage) {
       #if (AMIROOS_CFG_SSSP_STARTUP == true)
           /*
            * Deactivate S signal.
            * Master node delays execution by one period AOS_SSSP_DELAY.
            */
           case AOS_SSSP_STAGE_STARTUP_1_1:
+          {
       #if (AMIROOS_CFG_SSSP_MASTER == true)
             aosDbgCheck(listener == NULL);
             aosDbgCheck(flags == 0);
             aosDbgCheck(mask != 0);
             aosDbgCheck(received != NULL);
             // delay execution and deactivate the S signal on success
             if (_delay(AOS_SSSP_DELAY, mask, (laststage != AOS_SSSP_STAGE_STARTUP_1_1), received) == AOS_SUCCESS) {
               apalControlGpioSet(&moduleSsspGpioS, APAL_GPIO_OFF);
               nextstage = AOS_SSSP_STAGE_STARTUP_1_2;
+            }
       #else /* (AMIROOS_CFG_SSSP_MASTER == true) */
             aosDbgCheck(listener == NULL);
             aosDbgCheck(flags == 0);
             aosDbgCheck(mask == 0);
             aosDbgCheck(received == NULL);
             // deactivate S signal and proceed
             apalControlGpioSet(&moduleSsspGpioS, APAL_GPIO_OFF);
             nextstage = AOS_SSSP_STAGE_STARTUP_1_2;
       #endif /* (AMIROOS_CFG_SSSP_MASTER == true) */
             break;
+          }
           /*
            * Wait for the S signal to become inactive.
            */
           case AOS_SSSP_STAGE_STARTUP_1_2:
+          {
             aosDbgCheck(listener != NULL);
             aosDbgCheck(flags != 0);
             aosDbgCheck(mask == listener->events);
             aosDbgCheck(received != NULL);
             // wait for the S signal to become inactive and proceed on success
             if (_waitForS(listener, flags, APAL_GPIO_OFF, received) == AOS_SUCCESS) {
               nextstage = AOS_SSSP_STAGE_STARTUP_1_3;
+            }
             break;
+          }
           /*
            * Wait for the S signal to be activated by the master module.
            * The master delays execution by one period AOS_SSSP_DELAY.
            */
           case AOS_SSSP_STAGE_STARTUP_1_3:
+          {
       #if (AMIROOS_CFG_SSSP_MASTER == true)
             aosDbgCheck(listener == NULL);
             aosDbgCheck(flags == 0);
             aosDbgCheck(mask != 0);
             aosDbgCheck(received != NULL);
             // delay execution and deactivate the S signal on success
             if (_delay(AOS_SSSP_DELAY, mask, (laststage != AOS_SSSP_STAGE_STARTUP_1_3), received) == AOS_SUCCESS) {
               apalControlGpioSet(&moduleSsspGpioS, APAL_GPIO_ON);
               nextstage = AOS_SSSP_STAGE_STARTUP_2_1;
+            }
       #else /* (AMIROOS_CFG_SSSP_MASTER == true) */
             aosDbgCheck(listener != NULL);
             aosDbgCheck(flags != 0);
             aosDbgCheck(mask == listener->events);
             aosDbgCheck(received != NULL);
             // wait for the S signal to become active and activate it as well and proceed on success
             if (_waitForS(listener, flags, APAL_GPIO_ON, received) == AOS_SUCCESS) {
               apalControlGpioSet(&moduleSsspGpioS, APAL_GPIO_ON);
               nextstage = AOS_SSSP_STAGE_STARTUP_2_1;
+            }
       #endif /* (AMIROOS_CFG_SSSP_MASTER == true) */
             break;
+          }
       #endif /* (AMIROOS_CFG_SSSP_STARTUP == true) */
           /*
            * Deactivate S signal.
            * Master node delays execution by one period AOS_SSSP_DELAY
            */
           case AOS_SSSP_STAGE_STARTUP_2_1:
+          {
       #if (AMIROOS_CFG_SSSP_MASTER == true)
             aosDbgCheck(listener == NULL);
             aosDbgCheck(flags == 0);
             aosDbgCheck(mask != 0);
             aosDbgCheck(received != NULL);
             // delay execution and deactivate the S signal on success
             if (_delay(AOS_SSSP_DELAY, mask, (laststage != AOS_SSSP_STAGE_STARTUP_2_1), received) == AOS_SUCCESS) {
               apalControlGpioSet(&moduleSsspGpioS, APAL_GPIO_OFF);
               nextstage = AOS_SSSP_STAGE_STARTUP_2_2;
+            }
       #else /* (AMIROOS_CFG_SSSP_MASTER == true) */
             aosDbgCheck(listener == NULL);
             aosDbgCheck(flags == 0);
             aosDbgCheck(mask == 0);
             aosDbgCheck(received == NULL);
             // deactivate S signal and proceed
             apalControlGpioSet(&moduleSsspGpioS, APAL_GPIO_OFF);
             nextstage = AOS_SSSP_STAGE_STARTUP_2_2;
             mask = 0;
       #endif /* (AMIROOS_CFG_SSSP_MASTER == true) */
             break;
+          }
           /*
            * Wait for the S signal to become inactive.
            * When proceeding to operation phase, the master starts toggling S for synchronization
            */
           case AOS_SSSP_STAGE_STARTUP_2_2:
+          {
             aosDbgCheck(listener != NULL);
             aosDbgCheck(flags != 0);
             aosDbgCheck(mask == listener->events);
             aosDbgCheck(received != NULL);
             // wait for the S signal to become inactive and proceed on success
             if (_waitForS(listener, flags, APAL_GPIO_OFF, received) == AOS_SUCCESS) {
       #if (AMIROOS_CFG_SSSP_MSI == true)
               nextstage = AOS_SSSP_STAGE_STARTUP_3;
       #else /* (AMIROOS_CFG_SSSP_MSI == true) */
               chSysLock();
               // start the internal uptime aggregation
               aosSysStartUptimeS();
       #if (AMIROOS_CFG_SSSP_MASTER == true)
               // start toggling S for system synchronization
               _syncTimerStartS();
       #endif /* (AMIROOS_CFG_SSSP_MASTER == true) */
               chSysUnlock();
               nextstage = AOS_SSSP_STAGE_OPERATION;
       #endif /* (AMIROOS_CFG_SSSP_MSI == true) */
+            }
             break;
+          }
       #if (AMIROOS_CFG_SSSP_MSI == true)
             //TODO
       #endif /* (AMIROOS_CFG_SSSP_MSI == true) */
           /*
            * Invalid operation.
            * Shutdon must be initiatid via the aosSsspShutdownInit() function.
            */
           case AOS_SSSP_STAGE_OPERATION:
+          {
             aosDbgAssertMsg(false, "in order to exit operation phase, aosSsspShutdownInit() function must be used");
             break;
+          }
           /*
            * Delay execution by one perion AOS_SSSP_DELAY, deactivate the SYNC signal and proceed.
            * NOTE: Actually only the module that initiated the shutdown has to delay execution here.
            *       For the sake of simlicity though, each module delays execution.
            */
           case AOS_SSSP_STAGE_SHUTDOWN_1_2:
+          {
             aosDbgCheck(listener == NULL);
             aosDbgCheck(flags == 0);
             aosDbgCheck(mask == 0);
             aosDbgCheck(received == NULL);
             // delay execution
             aosThdUSleep(AOS_SSSP_DELAY);
             // deactivate S signal
             apalControlGpioSet(&moduleSsspGpioS, APAL_GPIO_OFF);
             nextstage = AOS_SSSP_STAGE_SHUTDOWN_1_3;
             break;
+          }
       #if (AMIROOS_CFG_SSSP_SHUTDOWN == true)
           /*
            * Wait for S signal to become inactive.
            */
           case AOS_SSSP_STAGE_SHUTDOWN_1_3:
+          {
             aosDbgCheck(listener != NULL);
             aosDbgCheck(flags != 0);
             aosDbgCheck(mask == listener->events);
             aosDbgCheck(received != NULL);
             // wait for the S signal to become inactive and proceed on success
             if (_waitForS(listener, flags, APAL_GPIO_OFF, received) == AOS_SUCCESS) {
               nextstage = AOS_SSSP_STAGE_SHUTDOWN_2_1;
+            }
             break;
+          }
           /*
            * Evaluate PD signal to determine whether a shutdown or restart is requested.
            * The logical state is returned by the function call.
            */
           case AOS_SSSP_STAGE_SHUTDOWN_2_1:
+          {
             aosDbgCheck(listener == NULL);
             aosDbgCheck(flags == 0);
             aosDbgCheck(mask == 0);
             aosDbgCheck(received != NULL);
             // evaluate PD signal
             apalControlGpioState_t pd;
             apalControlGpioGet(&moduleSsspGpioPD, &pd);
             *received = (pd == APAL_GPIO_ON) ? (eventmask_t)~0 : 0;
             nextstage = AOS_SSSP_STAGE_SHUTDOWN_2_2;
             break;
+          }
           /*
            * Proceed with no further actions required.
            */
           case AOS_SSSP_STAGE_SHUTDOWN_2_2:
+          {
             aosDbgCheck(listener == NULL);
             aosDbgCheck(flags == 0);
             aosDbgCheck(mask == 0);
             aosDbgCheck(received == NULL);
             nextstage = AOS_SSSP_STAGE_SHUTDOWN_2_3;
             break;
+          }
       #endif /* (AMIROOS_CFG_SSSP_SHUTDOWN == true) */
           default:
+          {
             // this case must never occur!
             aosDbgAssertMsg(false, "Invalid SSSP stage tranition occurred");
             break;
+          }
         } /* end of switch (aos.sssp.stage) */
         // outro and return
         laststage = aos.sssp.stage;
         const aos_status_t status = (nextstage > aos.sssp.stage) ? AOS_SUCCESS : AOS_FAILURE;
         aos.sssp.stage = nextstage;
         return status;
+      }
       /**
        * @brief   Leave the operation pahse and initiate or acknowledge shutdown.
+       *
        * @param[in] active  Flag, indicating whether the shutdon shall be activeliy initiated (true) or a passive request was received (false).
        */
       void aosSsspShutdownInit(bool active)
+      {
         aosDbgAssert(aos.sssp.stage == AOS_SSSP_STAGE_OPERATION);
         // proceed to shutdown phase
         aos.sssp.stage = AOS_SSSP_STAGE_SHUTDOWN_1_1;
         // activate PD if this was an active shutdown initiation
         if (active) {
           apalControlGpioSet(&moduleSsspGpioPD, APAL_GPIO_ON);
+        }
       #if (AMIROOS_CFG_SSSP_MASTER == true)
         // stop toggling S
         chVTReset(&_synctimer);
       #endif /* (AMIROOS_CFG_SSSP_MASTER == true) */
         // activate S
         apalControlGpioSet(&moduleSsspGpioS, APAL_GPIO_ON);
         // proceed in the shutdown phase
         aos.sssp.stage = AOS_SSSP_STAGE_SHUTDOWN_1_2;
         return;
+      }
       #if (AMIROOS_CFG_SSSP_SHUTDOWN == true) || defined(__DOXYGEN__)
       /**
        * @brief   Sequnetially broadcast an identifier via S to specify a specific way to shutdown or restart.
+       *
        * @param[in] identifier  Identifier to be broadcasted.
        */
       void aosSsspShutdownBroadcastIdentifier(unsigned int identifier)
+      {
         // only broadcast anything if a identifier greater than 0 was specified
         if (identifier > 0) {
           // broadcast identifier
           for (unsigned int pulse = 0; pulse < identifier; ++pulse) {
             // wait one delay time with S being deactivated
             aosThdUSleep(AOS_SSSP_DELAY);
             // activate S for one AOS_SSSP_DELAY.
             apalControlGpioSet(&moduleSsspGpioS, APAL_GPIO_ON);
             aosThdUSleep(AOS_SSSP_DELAY);
             apalControlGpioSet(&moduleSsspGpioS, APAL_GPIO_OFF);
+          }
+        }
         // let a timeout pass and return
         aosThdUSleep(AOS_SSSP_TIMEOUT);
         return;
+      }
       /**
        * @brief   Wait for a pulse during the SSSP shutdown disambiguation procedure.
        * @details Whenever a pulse is received, the identifier is incremented.
        *          Otherwise the internal timer is configured and will eventually trigger a timeout event.
+       *
        * @param[in]     gpiolistener  Event listener for GPIO events.
        * @param[in]     sflags        Event flags to be set by edges on the S signal.
        * @param[in]     timermask     Event maks to use for the internal timer.
        * @param[in,out] identifier    Identifier variable to increment.
+       *
        * @return  The event mask of whatever event was received during this function call.
        */
       eventmask_t aosSsspShutdownWaitForIdentifierPulse(event_listener_t* gpiolistener, const eventflags_t sflags, eventmask_t timermask, unsigned int* identifier)
+      {
         aosDbgCheck(gpiolistener != NULL);
         aosDbgCheck(sflags != 0);
         aosDbgCheck(timermask != 0);
         aosDbgCheck(identifier != NULL);
         // local variables
         eventmask_t mask;
         eventflags_t flags;
         apalControlGpioState_t sstate;
         // arm the timer once
         if (!chVTIsArmed(&_delayTimer)) {
           chEvtRegisterMask(&_eventSourceDelay, &_eventListenerDelay, timermask);
           chVTSet(&_delayTimer, chTimeUS2I(AOS_SSSP_TIMEOUT), _timerCallback, &_eventSourceDelay);
+        }
         // wait for any event to occur (do not apply any filters in order not to miss any events)
         mask = chEvtWaitOne(ALL_EVENTS);
         // GPIO event
         if (mask & gpiolistener->events) {
           // retreive flags without clearing them
           flags = gpiolistener->flags;
           apalControlGpioGet(&moduleSsspGpioS, &sstate);
           if (flags == sflags) {
             apalControlGpioGet(&moduleSsspGpioS, &sstate);
             // if this was the end of a pulse
             if (sstate == APAL_GPIO_OFF) {
               // restart the timer
               chVTReset(&_delayTimer);
               chVTSet(&_delayTimer, chTimeUS2I(AOS_SSSP_TIMEOUT), _timerCallback, &_eventSourceDelay);
               // increment the identifier
               ++(*identifier);
+            }
+          }
+        }
         // timer event
         else if (mask & _eventListenerDelay.events) {
           // unregister event
           chEvtUnregister(&_eventSourceDelay, &_eventListenerDelay);
+        }
         // any further events must be handled externally
         return mask;
+      }
       #endif /* (AMIROOS_CFG_SSSP_SHUTDOWN == true) */
       #if ((AMIROOS_CFG_SSSP_MASTER != true) && (AMIROOS_CFG_PROFILE == true)) || defined(__DOXYGEN__)
       /**
        * @brief   Retreive the offset between local clock and system synchronization signal.
+       *
        * @return
        */
       float aosSsspGetSyncSkew(void)
+      {
         return _syncskew;
+      }
       #endif /* (AMIROOS_CFG_SSSP_MASTER != true) && (AMIROOS_CFG_PROFILE == true) */
       #endif /* (AMIROOS_CFG_SSSP_ENABLE == true) */
       /** @} */