Baseline the Giant Gecko demo, which now has the first pass at a low power tickless implementation.
Richard Barry
9 years ago
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8ef7849199
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/*
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FreeRTOS V8.2.3 - Copyright (C) 2015 Real Time Engineers Ltd.
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All rights reserved
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VISIT http://www.FreeRTOS.org TO ENSURE YOU ARE USING THE LATEST VERSION.
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This file is part of the FreeRTOS distribution.
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FreeRTOS is free software; you can redistribute it and/or modify it under
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the terms of the GNU General Public License (version 2) as published by the
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Free Software Foundation >>>> AND MODIFIED BY <<<< the FreeRTOS exception.
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***************************************************************************
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>>! NOTE: The modification to the GPL is included to allow you to !<<
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>>! distribute a combined work that includes FreeRTOS without being !<<
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>>! obliged to provide the source code for proprietary components !<<
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>>! outside of the FreeRTOS kernel. !<<
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***************************************************************************
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FreeRTOS is distributed in the hope that it will be useful, but WITHOUT ANY
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WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
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FOR A PARTICULAR PURPOSE. Full license text is available on the following
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link: http://www.freertos.org/a00114.html
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***************************************************************************
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* *
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***************************************************************************
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http://www.FreeRTOS.org/FAQHelp.html - Having a problem? Start by reading
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the FAQ page "My application does not run, what could be wrong?". Have you
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defined configASSERT()?
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http://www.FreeRTOS.org/training - Investing in training allows your team to
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be as productive as possible as early as possible. Now you can receive
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1 tab == 4 spaces!
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*/
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/* Standard includes. */
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#include "limits.h"
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/* FreeRTOS includes. */
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#include "FreeRTOS.h"
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#include "task.h"
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/* SiLabs library includes. */
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#include "em_cmu.h"
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#include "em_burtc.h"
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#include "em_rmu.h"
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#include "em_int.h"
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#include "sleep.h"
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/* This file contains functions that will override the default implementations
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in the RTOS port layer. Therefore only build this file if the low power demo
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is being built. */
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#if( configCREATE_LOW_POWER_DEMO == 1 )
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#define mainTIMER_FREQUENCY_HZ ( 2000UL )
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/*
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* The low power demo does not use the SysTick, so override the
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* vPortSetupTickInterrupt() function with an implementation that configures
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* a low power clock source. NOTE: This function name must not be changed as
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* it is called from the RTOS portable layer.
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*/
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void vPortSetupTimerInterrupt( void );
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/* Override the default definition of vPortSuppressTicksAndSleep() that is
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* weakly defined in the FreeRTOS Cortex-M port layer with a version that
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* manages the BURTC clock, as the tick is generated from the low power BURTC
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* and not the SysTick as would normally be the case on a Cortex-M.
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*/
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void vPortSuppressTicksAndSleep( TickType_t xExpectedIdleTime );
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/*-----------------------------------------------------------*/
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/* Calculate how many clock increments make up a single tick period. */
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static const uint32_t ulReloadValueForOneTick = ( mainTIMER_FREQUENCY_HZ / configTICK_RATE_HZ );
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/* Calculate the maximum number of ticks that can be suppressed when using the
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high resolution clock and low resolution clock respectively. */
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static uint32_t xMaximumPossibleSuppressedTicks = 0;
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/* Flag set from the tick interrupt to allow the sleep processing to know if
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sleep mode was exited because of an timer interrupt or a different interrupt. */
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static volatile uint32_t ulTickFlag = pdFALSE;
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/* As the clock is only 2KHz, it is likely a value of 1 will be too much, so
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use zero - but leave the value here to assist porting to different clock
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speeds. */
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static const uint32_t ulStoppedTimerCompensation = 0UL;
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/*-----------------------------------------------------------*/
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void vPortSetupTimerInterrupt( void )
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{
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BURTC_Init_TypeDef xBURTCInitStruct = BURTC_INIT_DEFAULT;
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xMaximumPossibleSuppressedTicks = ULONG_MAX / ulReloadValueForOneTick;
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/* Ensure LE modules are accessible. */
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CMU_ClockEnable( cmuClock_CORELE, true );
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/* Enable access to BURTC registers. */
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RMU_ResetControl( rmuResetBU, false );
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/* Generate the tick interrupt from BURTC. */
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xBURTCInitStruct.mode = burtcModeEM3; /* Operational in EM3. */
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xBURTCInitStruct.clkSel = burtcClkSelULFRCO;/* ULFRCO clock. */
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xBURTCInitStruct.clkDiv = burtcClkDiv_1; /* 2kHz ULFRCO clock. */
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xBURTCInitStruct.compare0Top = true; /* Wrap on COMP0. */
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BURTC_IntDisable( BURTC_IF_COMP0 );
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BURTC_Init( &xBURTCInitStruct );
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/* The tick interrupt must be set to the lowest possible. */
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NVIC_SetPriority( BURTC_IRQn, configKERNEL_INTERRUPT_PRIORITY );
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NVIC_ClearPendingIRQ( BURTC_IRQn );
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NVIC_EnableIRQ( BURTC_IRQn );
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BURTC_CompareSet( 0, ulReloadValueForOneTick );
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BURTC_IntClear( BURTC_IF_COMP0 );
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BURTC_IntEnable( BURTC_IF_COMP0 );
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BURTC_CounterReset();
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}
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/*-----------------------------------------------------------*/
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void vPortSuppressTicksAndSleep( TickType_t xExpectedIdleTime )
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{
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uint32_t ulReloadValue, ulCompleteTickPeriods, ulCurrentCount;
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eSleepModeStatus eSleepAction;
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TickType_t xModifiableIdleTime;
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/* THIS FUNCTION IS CALLED WITH THE SCHEDULER SUSPENDED. */
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/* Make sure the BURTC reload value does not overflow the counter. */
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if( xExpectedIdleTime > xMaximumPossibleSuppressedTicks )
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{
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xExpectedIdleTime = xMaximumPossibleSuppressedTicks;
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}
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/* Calculate the reload value required to wait xExpectedIdleTime tick
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periods. */
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ulReloadValue = ulReloadValueForOneTick * xExpectedIdleTime;
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if( ulReloadValue > ulStoppedTimerCompensation )
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{
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/* Compensate for the fact that the BURTC is going to be stopped
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momentarily. */
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ulReloadValue -= ulStoppedTimerCompensation;
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}
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/* Stop the BURTC momentarily. The time the BURTC is stopped for is
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accounted for as best it can be, but using the tickless mode will inevitably
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result in some tiny drift of the time maintained by the kernel with respect
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to calendar time. The count is latched before stopping the timer as
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stopping the timer appears to clear the count. */
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ulCurrentCount = BURTC_CounterGet();
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BURTC_Enable( false );
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/* Enter a critical section but don't use the taskENTER_CRITICAL() method as
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that will mask interrupts that should exit sleep mode. */
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INT_Disable();
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/* The tick flag is set to false before sleeping. If it is true when sleep
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mode is exited then sleep mode was probably exited because the tick was
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suppressed for the entire xExpectedIdleTime period. */
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ulTickFlag = pdFALSE;
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/* If a context switch is pending then abandon the low power entry as the
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context switch might have been pended by an external interrupt that requires
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processing. */
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eSleepAction = eTaskConfirmSleepModeStatus();
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if( eSleepAction == eAbortSleep )
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{
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/* Restart tick and count up to whatever was left of the current time
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slice. */
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BURTC_CompareSet( 0, ulReloadValueForOneTick - ulCurrentCount );
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BURTC_Enable( true );
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/* Re-enable interrupts - see comments above the cpsid instruction()
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above. */
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INT_Enable();
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}
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else
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{
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/* Adjust the reload value to take into account that the current time
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slice is already partially complete. */
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ulReloadValue -= ulCurrentCount;
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BURTC_CompareSet( 0, ulReloadValue );
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/* Restart the BURTC. */
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BURTC_Enable( true );
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/* Allow the application to define some pre-sleep processing. */
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xModifiableIdleTime = xExpectedIdleTime;
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configPRE_SLEEP_PROCESSING( xModifiableIdleTime );
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/* xExpectedIdleTime being set to 0 by configPRE_SLEEP_PROCESSING()
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means the application defined code has already executed the WAIT
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instruction. */
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if( xModifiableIdleTime > 0 )
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{
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__asm volatile( "dsb" );
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SLEEP_Sleep();
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__asm volatile( "isb" );
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}
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/* Allow the application to define some post sleep processing. */
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configPOST_SLEEP_PROCESSING( xModifiableIdleTime );
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/* Stop BURTC. Again, the time the SysTick is stopped for is accounted
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for as best it can be, but using the tickless mode will inevitably
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result in some tiny drift of the time maintained by the kernel with
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respect to calendar time. The count value is latched before stopping
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the timer as stopping the timer appears to clear the count. */
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ulCurrentCount = BURTC_CounterGet();
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BURTC_Enable( false );
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/* Re-enable interrupts - see comments above the cpsid instruction()
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above. */
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INT_Enable();
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if( ulTickFlag != pdFALSE )
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{
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/* The tick interrupt has already executed, although because this
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function is called with the scheduler suspended the actual tick
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processing will not occur until after this function has exited.
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Reset the reload value with whatever remains of this tick period. */
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ulReloadValue = ulReloadValueForOneTick - ulCurrentCount;
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BURTC_CompareSet( 0, ulReloadValue );
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/* The tick interrupt handler will already have pended the tick
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processing in the kernel. As the pending tick will be processed as
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soon as this function exits, the tick value maintained by the tick
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is stepped forward by one less than the time spent sleeping. The
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actual stepping of the tick appears later in this function. */
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ulCompleteTickPeriods = xExpectedIdleTime - 1UL;
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}
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else
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{
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/* Something other than the tick interrupt ended the sleep. How
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many complete tick periods passed while the processor was
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sleeping? */
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ulCompleteTickPeriods = ulCurrentCount / ulReloadValueForOneTick;
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/* The reload value is set to whatever fraction of a single tick
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period remains. */
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ulReloadValue = ulCurrentCount - ( ulCompleteTickPeriods * ulReloadValueForOneTick );
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if( ulReloadValue == 0 )
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{
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/* There is no fraction remaining. */
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ulReloadValue = ulReloadValueForOneTick;
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ulCompleteTickPeriods++;
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}
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BURTC_CompareSet( 0, ulReloadValue );
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}
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/* Restart the BURTC so it runs up to the alarm value. The alarm value
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will get set to the value required to generate exactly one tick period
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the next time the BURTC interrupt executes. */
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BURTC_Enable( true );
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/* Wind the tick forward by the number of tick periods that the CPU
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remained in a low power state. */
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vTaskStepTick( ulCompleteTickPeriods );
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}
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}
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/*-----------------------------------------------------------*/
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void BURTC_IRQHandler(void)
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{
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if( ulTickFlag == pdFALSE )
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{
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/* Set BURTC interrupt to one system tick period*/
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BURTC_Enable( false );
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BURTC_CompareSet( 0, ulReloadValueForOneTick );
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ulTickFlag = pdTRUE;
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BURTC_Enable( true );
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}
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BURTC_IntClear( _RTC_IFC_MASK );
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/* Critical section which protect incrementing the tick*/
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( void ) portSET_INTERRUPT_MASK_FROM_ISR();
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{
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if( xTaskIncrementTick() != pdFALSE )
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{
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/* Pend a context switch. */
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portNVIC_INT_CTRL_REG = portNVIC_PENDSVSET_BIT;
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}
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}
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portCLEAR_INTERRUPT_MASK_FROM_ISR( 0 );
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}
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#endif /* ( configCREATE_LOW_POWER_DEMO == 1 ) */
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