Cortex M0 GCC/IAR/Keil ports -- tickless support.

The default portMISSED_COUNTS_FACTOR is set to 45 cycles. User could override this value, if a more accurate count is available. 

git-svn-id: http://svn.code.sf.net/p/freertos/code/trunk@2764 1d2547de-c912-0410-9cb9-b8ca96c0e9e2

6 files changed, 689 insertions, 52 deletions

diff --git a/FreeRTOS/Source/portable/GCC/ARM_CM0/port.c b/FreeRTOS/Source/portable/GCC/ARM_CM0/port.c
index d0b50c392..18a668b9b 100644
--- a/FreeRTOS/Source/portable/GCC/ARM_CM0/port.c
+++ b/FreeRTOS/Source/portable/GCC/ARM_CM0/port.c
@@ -34,15 +34,16 @@
 #include "task.h"

 

 /* Constants required to manipulate the NVIC. */

-#define portNVIC_SYSTICK_CTRL			( ( volatile uint32_t * ) 0xe000e010 )

-#define portNVIC_SYSTICK_LOAD			( ( volatile uint32_t * ) 0xe000e014 )

-#define portNVIC_SYSTICK_CURRENT_VALUE	( ( volatile uint32_t * ) 0xe000e018 )

-#define portNVIC_INT_CTRL				( ( volatile uint32_t *) 0xe000ed04 )

-#define portNVIC_SYSPRI2				( ( volatile uint32_t *) 0xe000ed20 )

-#define portNVIC_SYSTICK_CLK			0x00000004

-#define portNVIC_SYSTICK_INT			0x00000002

-#define portNVIC_SYSTICK_ENABLE			0x00000001

-#define portNVIC_PENDSVSET				0x10000000

+#define portNVIC_SYSTICK_CTRL_REG			( * ( ( volatile uint32_t * ) 0xe000e010 ) )

+#define portNVIC_SYSTICK_LOAD_REG			( * ( ( volatile uint32_t * ) 0xe000e014 ) )

+#define portNVIC_SYSTICK_CURRENT_VALUE_REG	( * ( ( volatile uint32_t * ) 0xe000e018 ) )

+#define portNVIC_INT_CTRL_REG				( * ( ( volatile uint32_t * ) 0xe000ed04 ) )

+#define portNVIC_SYSPRI2_REG				( * ( ( volatile uint32_t * ) 0xe000ed20 ) )

+#define portNVIC_SYSTICK_CLK_BIT			( 1UL << 2UL )

+#define portNVIC_SYSTICK_INT_BIT			( 1UL << 1UL )

+#define portNVIC_SYSTICK_ENABLE_BIT			( 1UL << 0UL )

+#define portNVIC_SYSTICK_COUNT_FLAG_BIT		( 1UL << 16UL )

+#define portNVIC_PENDSVSET_BIT				( 1UL << 28UL )

 #define portMIN_INTERRUPT_PRIORITY		( 255UL )

 #define portNVIC_PENDSV_PRI				( portMIN_INTERRUPT_PRIORITY << 16UL )

 #define portNVIC_SYSTICK_PRI			( portMIN_INTERRUPT_PRIORITY << 24UL )

@@ -50,6 +51,16 @@
 /* Constants required to set up the initial stack. */

 #define portINITIAL_XPSR			( 0x01000000 )

 

+/* The systick is a 24-bit counter. */

+#define portMAX_24_BIT_NUMBER				( 0xffffffUL )

+

+/* A fiddle factor to estimate the number of SysTick counts that would have

+occurred while the SysTick counter is stopped during tickless idle

+calculations. */

+#ifndef portMISSED_COUNTS_FACTOR

+	#define portMISSED_COUNTS_FACTOR			( 45UL )

+#endif

+

 /* Let the user override the pre-loading of the initial LR with the address of

 prvTaskExitError() in case it messes up unwinding of the stack in the

 debugger. */

@@ -90,6 +101,31 @@ static UBaseType_t uxCriticalNesting = 0xaaaaaaaa;
 /*-----------------------------------------------------------*/

 

 /*

+* The number of SysTick increments that make up one tick period.

+*/

+#if( configUSE_TICKLESS_IDLE == 1 )

+	static uint32_t ulTimerCountsForOneTick = 0;

+#endif /* configUSE_TICKLESS_IDLE */

+

+/*

+ * The maximum number of tick periods that can be suppressed is limited by the

+ * 24 bit resolution of the SysTick timer.

+ */

+#if( configUSE_TICKLESS_IDLE == 1 )

+	static uint32_t xMaximumPossibleSuppressedTicks = 0;

+#endif /* configUSE_TICKLESS_IDLE */

+

+/*

+ * Compensate for the CPU cycles that pass while the SysTick is stopped (low

+ * power functionality only.

+ */

+#if( configUSE_TICKLESS_IDLE == 1 )

+	static uint32_t ulStoppedTimerCompensation = 0;

+#endif /* configUSE_TICKLESS_IDLE */

+

+/*-----------------------------------------------------------*/

+

+/*

  * See header file for description.

  */

 StackType_t *pxPortInitialiseStack( StackType_t *pxTopOfStack, TaskFunction_t pxCode, void *pvParameters )

@@ -176,8 +212,8 @@ void vPortStartFirstTask( void )
 BaseType_t xPortStartScheduler( void )

 {

 	/* Make PendSV, CallSV and SysTick the same priority as the kernel. */

-	*(portNVIC_SYSPRI2) |= portNVIC_PENDSV_PRI;

-	*(portNVIC_SYSPRI2) |= portNVIC_SYSTICK_PRI;

+	portNVIC_SYSPRI2_REG |= portNVIC_PENDSV_PRI;

+	portNVIC_SYSPRI2_REG |= portNVIC_SYSTICK_PRI;

 

 	/* Start the timer that generates the tick ISR.  Interrupts are disabled

 	here already. */

@@ -214,7 +250,7 @@ void vPortEndScheduler( void )
 void vPortYield( void )

 {

 	/* Set a PendSV to request a context switch. */

-	*( portNVIC_INT_CTRL ) = portNVIC_PENDSVSET;

+	portNVIC_INT_CTRL_REG = portNVIC_PENDSVSET_BIT;

 

 	/* Barriers are normally not required but do ensure the code is completely

 	within the specified behaviour for the architecture. */

@@ -323,7 +359,7 @@ uint32_t ulPreviousMask;
 		if( xTaskIncrementTick() != pdFALSE )

 		{

 			/* Pend a context switch. */

-			*(portNVIC_INT_CTRL) = portNVIC_PENDSVSET;

+			portNVIC_INT_CTRL_REG = portNVIC_PENDSVSET_BIT;

 		}

 	}

 	portCLEAR_INTERRUPT_MASK_FROM_ISR( ulPreviousMask );

@@ -336,13 +372,187 @@ uint32_t ulPreviousMask;
  */

 void prvSetupTimerInterrupt( void )

 {

+	/* Calculate the constants required to configure the tick interrupt. */

+	#if( configUSE_TICKLESS_IDLE == 1 )

+	{

+		ulTimerCountsForOneTick = ( configCPU_CLOCK_HZ / configTICK_RATE_HZ );

+		xMaximumPossibleSuppressedTicks = portMAX_24_BIT_NUMBER / ulTimerCountsForOneTick;

+		ulStoppedTimerCompensation = portMISSED_COUNTS_FACTOR;

+	}

+	#endif /* configUSE_TICKLESS_IDLE */

+

 	/* Stop and reset the SysTick. */

-	*(portNVIC_SYSTICK_CTRL) = 0UL;

-	*(portNVIC_SYSTICK_CURRENT_VALUE) = 0UL;

+	portNVIC_SYSTICK_CTRL_REG = 0UL;

+	portNVIC_SYSTICK_CURRENT_VALUE_REG = 0UL;

 

 	/* Configure SysTick to interrupt at the requested rate. */

-	*(portNVIC_SYSTICK_LOAD) = ( configCPU_CLOCK_HZ / configTICK_RATE_HZ ) - 1UL;

-	*(portNVIC_SYSTICK_CTRL) = portNVIC_SYSTICK_CLK | portNVIC_SYSTICK_INT | portNVIC_SYSTICK_ENABLE;

+	portNVIC_SYSTICK_LOAD_REG = ( configCPU_CLOCK_HZ / configTICK_RATE_HZ ) - 1UL;

+	portNVIC_SYSTICK_CTRL_REG = portNVIC_SYSTICK_CLK_BIT | portNVIC_SYSTICK_INT_BIT | portNVIC_SYSTICK_ENABLE_BIT;

 }

 /*-----------------------------------------------------------*/

 

+#if( configUSE_TICKLESS_IDLE == 1 )

+

+	__attribute__((weak)) void vPortSuppressTicksAndSleep( TickType_t xExpectedIdleTime )

+	{

+	uint32_t ulReloadValue, ulCompleteTickPeriods, ulCompletedSysTickDecrements;

+	TickType_t xModifiableIdleTime;

+

+		/* Make sure the SysTick reload value does not overflow the counter. */

+		if( xExpectedIdleTime > xMaximumPossibleSuppressedTicks )

+		{

+			xExpectedIdleTime = xMaximumPossibleSuppressedTicks;

+		}

+

+		/* Stop the SysTick momentarily.  The time the SysTick is stopped for

+		is accounted for as best it can be, but using the tickless mode will

+		inevitably result in some tiny drift of the time maintained by the

+		kernel with respect to calendar time. */

+		portNVIC_SYSTICK_CTRL_REG &= ~portNVIC_SYSTICK_ENABLE_BIT;

+

+		/* Calculate the reload value required to wait xExpectedIdleTime

+		tick periods.  -1 is used because this code will execute part way

+		through one of the tick periods. */

+		ulReloadValue = portNVIC_SYSTICK_CURRENT_VALUE_REG + ( ulTimerCountsForOneTick * ( xExpectedIdleTime - 1UL ) );

+		if( ulReloadValue > ulStoppedTimerCompensation )

+		{

+			ulReloadValue -= ulStoppedTimerCompensation;

+		}

+

+		/* Enter a critical section but don't use the taskENTER_CRITICAL()

+		method as that will mask interrupts that should exit sleep mode. */

+		__asm volatile( "cpsid i" ::: "memory" );

+		__asm volatile( "dsb" );

+		__asm volatile( "isb" );

+

+		/* If a context switch is pending or a task is waiting for the scheduler

+		to be unsuspended then abandon the low power entry. */

+		if( eTaskConfirmSleepModeStatus() == eAbortSleep )

+		{

+			/* Restart from whatever is left in the count register to complete

+			this tick period. */

+			portNVIC_SYSTICK_LOAD_REG = portNVIC_SYSTICK_CURRENT_VALUE_REG;

+

+			/* Restart SysTick. */

+			portNVIC_SYSTICK_CTRL_REG |= portNVIC_SYSTICK_ENABLE_BIT;

+

+			/* Reset the reload register to the value required for normal tick

+			periods. */

+			portNVIC_SYSTICK_LOAD_REG = ulTimerCountsForOneTick - 1UL;

+

+			/* Re-enable interrupts - see comments above the cpsid instruction()

+			above. */

+			__asm volatile( "cpsie i" ::: "memory" );

+		}

+		else

+		{

+			/* Set the new reload value. */

+			portNVIC_SYSTICK_LOAD_REG = ulReloadValue;

+

+			/* Clear the SysTick count flag and set the count value back to

+			zero. */

+			portNVIC_SYSTICK_CURRENT_VALUE_REG = 0UL;

+

+			/* Restart SysTick. */

+			portNVIC_SYSTICK_CTRL_REG |= portNVIC_SYSTICK_ENABLE_BIT;

+

+			/* Sleep until something happens.  configPRE_SLEEP_PROCESSING() can

+			set its parameter to 0 to indicate that its implementation contains

+			its own wait for interrupt or wait for event instruction, and so wfi

+			should not be executed again.  However, the original expected idle

+			time variable must remain unmodified, so a copy is taken. */

+			xModifiableIdleTime = xExpectedIdleTime;

+			configPRE_SLEEP_PROCESSING( xModifiableIdleTime );

+			if( xModifiableIdleTime > 0 )

+			{

+				__asm volatile( "dsb" ::: "memory" );

+				__asm volatile( "wfi" );

+				__asm volatile( "isb" );

+			}

+			configPOST_SLEEP_PROCESSING( xExpectedIdleTime );

+

+			/* Re-enable interrupts to allow the interrupt that brought the MCU

+			out of sleep mode to execute immediately.  see comments above

+			__disable_interrupt() call above. */

+			__asm volatile( "cpsie i" ::: "memory" );

+			__asm volatile( "dsb" );

+			__asm volatile( "isb" );

+

+			/* Disable interrupts again because the clock is about to be stopped

+			and interrupts that execute while the clock is stopped will increase

+			any slippage between the time maintained by the RTOS and calendar

+			time. */

+			__asm volatile( "cpsid i" ::: "memory" );

+			__asm volatile( "dsb" );

+			__asm volatile( "isb" );

+

+			/* Disable the SysTick clock without reading the

+			portNVIC_SYSTICK_CTRL_REG register to ensure the

+			portNVIC_SYSTICK_COUNT_FLAG_BIT is not cleared if it is set.  Again,

+			the time the SysTick is stopped for is accounted for as best it can

+			be, but using the tickless mode will inevitably result in some tiny

+			drift of the time maintained by the kernel with respect to calendar

+			time*/

+			portNVIC_SYSTICK_CTRL_REG = ( portNVIC_SYSTICK_CLK_BIT | portNVIC_SYSTICK_INT_BIT );

+

+			/* Determine if the SysTick clock has already counted to zero and

+			been set back to the current reload value (the reload back being

+			correct for the entire expected idle time) or if the SysTick is yet

+			to count to zero (in which case an interrupt other than the SysTick

+			must have brought the system out of sleep mode). */

+			if( ( portNVIC_SYSTICK_CTRL_REG & portNVIC_SYSTICK_COUNT_FLAG_BIT ) != 0 )

+			{

+				uint32_t ulCalculatedLoadValue;

+

+				/* The tick interrupt is already pending, and the SysTick count

+				reloaded with ulReloadValue.  Reset the

+				portNVIC_SYSTICK_LOAD_REG with whatever remains of this tick

+				period. */

+				ulCalculatedLoadValue = ( ulTimerCountsForOneTick - 1UL ) - ( ulReloadValue - portNVIC_SYSTICK_CURRENT_VALUE_REG );

+

+				/* Don't allow a tiny value, or values that have somehow

+				underflowed because the post sleep hook did something

+				that took too long. */

+				if( ( ulCalculatedLoadValue < ulStoppedTimerCompensation ) || ( ulCalculatedLoadValue > ulTimerCountsForOneTick ) )

+				{

+					ulCalculatedLoadValue = ( ulTimerCountsForOneTick - 1UL );

+				}

+

+				portNVIC_SYSTICK_LOAD_REG = ulCalculatedLoadValue;

+

+				/* As the pending tick will be processed as soon as this

+				function exits, the tick value maintained by the tick is stepped

+				forward by one less than the time spent waiting. */

+				ulCompleteTickPeriods = xExpectedIdleTime - 1UL;

+			}

+			else

+			{

+				/* Something other than the tick interrupt ended the sleep.

+				Work out how long the sleep lasted rounded to complete tick

+				periods (not the ulReload value which accounted for part

+				ticks). */

+				ulCompletedSysTickDecrements = ( xExpectedIdleTime * ulTimerCountsForOneTick ) - portNVIC_SYSTICK_CURRENT_VALUE_REG;

+

+				/* How many complete tick periods passed while the processor

+				was waiting? */

+				ulCompleteTickPeriods = ulCompletedSysTickDecrements / ulTimerCountsForOneTick;

+

+				/* The reload value is set to whatever fraction of a single tick

+				period remains. */

+				portNVIC_SYSTICK_LOAD_REG = ( ( ulCompleteTickPeriods + 1UL ) * ulTimerCountsForOneTick ) - ulCompletedSysTickDecrements;

+			}

+

+			/* Restart SysTick so it runs from portNVIC_SYSTICK_LOAD_REG

+			again, then set portNVIC_SYSTICK_LOAD_REG back to its standard

+			value. */

+			portNVIC_SYSTICK_CURRENT_VALUE_REG = 0UL;

+			portNVIC_SYSTICK_CTRL_REG |= portNVIC_SYSTICK_ENABLE_BIT;

+			vTaskStepTick( ulCompleteTickPeriods );

+			portNVIC_SYSTICK_LOAD_REG = ulTimerCountsForOneTick - 1UL;

+

+			/* Exit with interrpts enabled. */

+			__asm volatile( "cpsie i" ::: "memory" );

+		}

+	}

+

+#endif /* configUSE_TICKLESS_IDLE */

diff --git a/FreeRTOS/Source/portable/GCC/ARM_CM0/portmacro.h b/FreeRTOS/Source/portable/GCC/ARM_CM0/portmacro.h
index 108a55ed7..9ad565518 100644
--- a/FreeRTOS/Source/portable/GCC/ARM_CM0/portmacro.h
+++ b/FreeRTOS/Source/portable/GCC/ARM_CM0/portmacro.h
@@ -101,6 +101,13 @@ extern void vClearInterruptMaskFromISR( uint32_t ulMask )  __attribute__((naked)
 

 /*-----------------------------------------------------------*/

 

+/* Tickless idle/low power functionality. */

+#ifndef portSUPPRESS_TICKS_AND_SLEEP

+	extern void vPortSuppressTicksAndSleep( TickType_t xExpectedIdleTime );

+	#define portSUPPRESS_TICKS_AND_SLEEP( xExpectedIdleTime ) vPortSuppressTicksAndSleep( xExpectedIdleTime )

+#endif

+/*-----------------------------------------------------------*/

+

 /* Task function macros as described on the FreeRTOS.org WEB site. */

 #define portTASK_FUNCTION_PROTO( vFunction, pvParameters ) void vFunction( void *pvParameters )

 #define portTASK_FUNCTION( vFunction, pvParameters ) void vFunction( void *pvParameters )

diff --git a/FreeRTOS/Source/portable/IAR/ARM_CM0/port.c b/FreeRTOS/Source/portable/IAR/ARM_CM0/port.c
index 41b7d43e4..3dd08209d 100644
--- a/FreeRTOS/Source/portable/IAR/ARM_CM0/port.c
+++ b/FreeRTOS/Source/portable/IAR/ARM_CM0/port.c
@@ -37,13 +37,15 @@
 #include "task.h"

 

 /* Constants required to manipulate the NVIC. */

-#define portNVIC_SYSTICK_CTRL			( ( volatile uint32_t * ) 0xe000e010 )

-#define portNVIC_SYSTICK_LOAD			( ( volatile uint32_t * ) 0xe000e014 )

-#define portNVIC_SYSTICK_CURRENT_VALUE	( ( volatile uint32_t * ) 0xe000e018 )

-#define portNVIC_SYSPRI2			( ( volatile uint32_t *) 0xe000ed20 )

-#define portNVIC_SYSTICK_CLK		0x00000004

-#define portNVIC_SYSTICK_INT		0x00000002

-#define portNVIC_SYSTICK_ENABLE		0x00000001

+#define portNVIC_SYSTICK_CTRL_REG			( * ( ( volatile uint32_t * ) 0xe000e010 ) )

+#define portNVIC_SYSTICK_LOAD_REG			( * ( ( volatile uint32_t * ) 0xe000e014 ) )

+#define portNVIC_SYSTICK_CURRENT_VALUE_REG	( * ( ( volatile uint32_t * ) 0xe000e018 ) )

+#define portNVIC_INT_CTRL_REG				( * ( ( volatile uint32_t * ) 0xe000ed04 ) )

+#define portNVIC_SYSPRI2_REG				( * ( ( volatile uint32_t *) 0xe000ed20 ) )

+#define portNVIC_SYSTICK_CLK_BIT			( 1UL << 2UL )

+#define portNVIC_SYSTICK_INT_BIT			( 1UL << 1UL )

+#define portNVIC_SYSTICK_ENABLE_BIT			( 1UL << 0UL )

+#define portNVIC_SYSTICK_COUNT_FLAG_BIT		( 1UL << 16UL )

 #define portMIN_INTERRUPT_PRIORITY	( 255UL )

 #define portNVIC_PENDSV_PRI			( portMIN_INTERRUPT_PRIORITY << 16UL )

 #define portNVIC_SYSTICK_PRI		( portMIN_INTERRUPT_PRIORITY << 24UL )

@@ -62,6 +64,33 @@ FreeRTOS.org versions prior to V4.3.0 did not include this definition. */
 variable. */

 static UBaseType_t uxCriticalNesting = 0xaaaaaaaa;

 

+/* The systick is a 24-bit counter. */

+#define portMAX_24_BIT_NUMBER				( 0xffffffUL )

+

+/* A fiddle factor to estimate the number of SysTick counts that would have

+occurred while the SysTick counter is stopped during tickless idle

+calculations. */

+#ifndef portMISSED_COUNTS_FACTOR

+	#define portMISSED_COUNTS_FACTOR			( 45UL )

+#endif

+

+/* The number of SysTick increments that make up one tick period. */

+#if( configUSE_TICKLESS_IDLE == 1 )

+	static uint32_t ulTimerCountsForOneTick = 0;

+#endif /* configUSE_TICKLESS_IDLE */

+

+/* The maximum number of tick periods that can be suppressed is limited by the

+24 bit resolution of the SysTick timer. */

+#if( configUSE_TICKLESS_IDLE == 1 )

+	static uint32_t xMaximumPossibleSuppressedTicks = 0;

+#endif /* configUSE_TICKLESS_IDLE */

+

+/* Compensate for the CPU cycles that pass while the SysTick is stopped (low

+power functionality only. */

+#if( configUSE_TICKLESS_IDLE == 1 )

+	static uint32_t ulStoppedTimerCompensation = 0;

+#endif /* configUSE_TICKLESS_IDLE */

+

 /*

  * Setup the timer to generate the tick interrupts.

  */

@@ -125,8 +154,8 @@ static void prvTaskExitError( void )
 BaseType_t xPortStartScheduler( void )

 {

 	/* Make PendSV and SysTick the lowest priority interrupts. */

-	*(portNVIC_SYSPRI2) |= portNVIC_PENDSV_PRI;

-	*(portNVIC_SYSPRI2) |= portNVIC_SYSTICK_PRI;

+	portNVIC_SYSPRI2_REG |= portNVIC_PENDSV_PRI;

+	portNVIC_SYSPRI2_REG |= portNVIC_SYSTICK_PRI;

 

 	/* Start the timer that generates the tick ISR.  Interrupts are disabled

 	here already. */

@@ -154,7 +183,7 @@ void vPortEndScheduler( void )
 void vPortYield( void )

 {

 	/* Set a PendSV to request a context switch. */

-	*(portNVIC_INT_CTRL) = portNVIC_PENDSVSET;

+	portNVIC_INT_CTRL_REG = portNVIC_PENDSVSET;

 

 	/* Barriers are normally not required but do ensure the code is completely

 	within the specified behaviour for the architecture. */

@@ -193,7 +222,7 @@ uint32_t ulPreviousMask;
 		if( xTaskIncrementTick() != pdFALSE )

 		{

 			/* Pend a context switch. */

-			*(portNVIC_INT_CTRL) = portNVIC_PENDSVSET;

+			portNVIC_INT_CTRL_REG = portNVIC_PENDSVSET;

 		}

 	}

 	portCLEAR_INTERRUPT_MASK_FROM_ISR( ulPreviousMask );

@@ -206,13 +235,187 @@ uint32_t ulPreviousMask;
  */

 static void prvSetupTimerInterrupt( void )

 {

+	/* Calculate the constants required to configure the tick interrupt. */

+	#if( configUSE_TICKLESS_IDLE == 1 )

+	{

+		ulTimerCountsForOneTick = ( configCPU_CLOCK_HZ / configTICK_RATE_HZ );

+		xMaximumPossibleSuppressedTicks = portMAX_24_BIT_NUMBER / ulTimerCountsForOneTick;

+		ulStoppedTimerCompensation = portMISSED_COUNTS_FACTOR;

+	}

+	#endif /* configUSE_TICKLESS_IDLE */

+        

 	/* Stop and reset the SysTick. */

-	*(portNVIC_SYSTICK_CTRL) = 0UL;

-	*(portNVIC_SYSTICK_CURRENT_VALUE) = 0UL;

+	portNVIC_SYSTICK_CTRL_REG = 0UL;

+	portNVIC_SYSTICK_CURRENT_VALUE_REG = 0UL;

 

 	/* Configure SysTick to interrupt at the requested rate. */

-	*(portNVIC_SYSTICK_LOAD) = ( configCPU_CLOCK_HZ / configTICK_RATE_HZ ) - 1UL;

-	*(portNVIC_SYSTICK_CTRL) = portNVIC_SYSTICK_CLK | portNVIC_SYSTICK_INT | portNVIC_SYSTICK_ENABLE;

+	portNVIC_SYSTICK_LOAD_REG = ( configCPU_CLOCK_HZ / configTICK_RATE_HZ ) - 1UL;

+	portNVIC_SYSTICK_CTRL_REG = portNVIC_SYSTICK_CLK_BIT | portNVIC_SYSTICK_INT_BIT | portNVIC_SYSTICK_ENABLE_BIT;

 }

 /*-----------------------------------------------------------*/

 

+#if( configUSE_TICKLESS_IDLE == 1 )

+

+__weak void vPortSuppressTicksAndSleep( TickType_t xExpectedIdleTime )

+{

+uint32_t ulReloadValue, ulCompleteTickPeriods, ulCompletedSysTickDecrements;

+TickType_t xModifiableIdleTime;

+

+	/* Make sure the SysTick reload value does not overflow the counter. */

+	if( xExpectedIdleTime > xMaximumPossibleSuppressedTicks )

+	{

+		xExpectedIdleTime = xMaximumPossibleSuppressedTicks;

+	}

+

+	/* Stop the SysTick momentarily.  The time the SysTick is stopped for

+	is accounted for as best it can be, but using the tickless mode will

+	inevitably result in some tiny drift of the time maintained by the

+	kernel with respect to calendar time. */

+	portNVIC_SYSTICK_CTRL_REG &= ~portNVIC_SYSTICK_ENABLE_BIT;

+

+	/* Calculate the reload value required to wait xExpectedIdleTime

+	tick periods.  -1 is used because this code will execute part way

+	through one of the tick periods. */

+	ulReloadValue = portNVIC_SYSTICK_CURRENT_VALUE_REG + ( ulTimerCountsForOneTick * ( xExpectedIdleTime - 1UL ) );

+	if( ulReloadValue > ulStoppedTimerCompensation )

+	{

+		ulReloadValue -= ulStoppedTimerCompensation;

+	}

+

+	/* Enter a critical section but don't use the taskENTER_CRITICAL()

+	method as that will mask interrupts that should exit sleep mode. */

+	__disable_interrupt();

+	__DSB();

+	__ISB();

+

+	/* If a context switch is pending or a task is waiting for the scheduler

+	to be unsuspended then abandon the low power entry. */

+	if( eTaskConfirmSleepModeStatus() == eAbortSleep )

+	{

+		/* Restart from whatever is left in the count register to complete

+		this tick period. */

+		portNVIC_SYSTICK_LOAD_REG = portNVIC_SYSTICK_CURRENT_VALUE_REG;

+

+		/* Restart SysTick. */

+		portNVIC_SYSTICK_CTRL_REG |= portNVIC_SYSTICK_ENABLE_BIT;

+

+		/* Reset the reload register to the value required for normal tick

+		periods. */

+		portNVIC_SYSTICK_LOAD_REG = ulTimerCountsForOneTick - 1UL;

+

+		/* Re-enable interrupts - see comments above __disable_interrupt()

+		call above. */

+		__enable_interrupt();

+	}

+	else

+	{

+		/* Set the new reload value. */

+		portNVIC_SYSTICK_LOAD_REG = ulReloadValue;

+

+		/* Clear the SysTick count flag and set the count value back to

+		zero. */

+		portNVIC_SYSTICK_CURRENT_VALUE_REG = 0UL;

+

+		/* Restart SysTick. */

+		portNVIC_SYSTICK_CTRL_REG |= portNVIC_SYSTICK_ENABLE_BIT;

+

+		/* Sleep until something happens.  configPRE_SLEEP_PROCESSING() can

+		set its parameter to 0 to indicate that its implementation contains

+		its own wait for interrupt or wait for event instruction, and so wfi

+		should not be executed again.  However, the original expected idle

+		time variable must remain unmodified, so a copy is taken. */

+		xModifiableIdleTime = xExpectedIdleTime;

+		configPRE_SLEEP_PROCESSING( xModifiableIdleTime );

+		if( xModifiableIdleTime > 0 )

+		{

+			__DSB();

+			__WFI();

+			__ISB();

+		}

+		configPOST_SLEEP_PROCESSING( xExpectedIdleTime );

+

+		/* Re-enable interrupts to allow the interrupt that brought the MCU

+		out of sleep mode to execute immediately.  see comments above

+		__disable_interrupt() call above. */

+		__enable_interrupt();

+		__DSB();

+		__ISB();

+

+		/* Disable interrupts again because the clock is about to be stopped

+		and interrupts that execute while the clock is stopped will increase

+		any slippage between the time maintained by the RTOS and calendar

+		time. */

+		__disable_interrupt();

+		__DSB();

+		__ISB();

+

+		/* Disable the SysTick clock without reading the 

+		portNVIC_SYSTICK_CTRL_REG register to ensure the

+		portNVIC_SYSTICK_COUNT_FLAG_BIT is not cleared if it is set.  Again, 

+		the time the SysTick is stopped for is accounted for as best it can 

+		be, but using the tickless mode will inevitably result in some tiny 

+		drift of the time maintained by the kernel with respect to calendar 

+		time*/

+		portNVIC_SYSTICK_CTRL_REG = ( portNVIC_SYSTICK_CLK_BIT | portNVIC_SYSTICK_INT_BIT );

+

+		/* Determine if the SysTick clock has already counted to zero and

+		been set back to the current reload value (the reload back being

+		correct for the entire expected idle time) or if the SysTick is yet

+		to count to zero (in which case an interrupt other than the SysTick

+		must have brought the system out of sleep mode). */

+		if( ( portNVIC_SYSTICK_CTRL_REG & portNVIC_SYSTICK_COUNT_FLAG_BIT ) != 0 )

+		{

+			uint32_t ulCalculatedLoadValue;

+

+			/* The tick interrupt is already pending, and the SysTick count

+			reloaded with ulReloadValue.  Reset the

+			portNVIC_SYSTICK_LOAD_REG with whatever remains of this tick

+			period. */

+			ulCalculatedLoadValue = ( ulTimerCountsForOneTick - 1UL ) - ( ulReloadValue - portNVIC_SYSTICK_CURRENT_VALUE_REG );

+

+			/* Don't allow a tiny value, or values that have somehow

+			underflowed because the post sleep hook did something

+			that took too long. */

+			if( ( ulCalculatedLoadValue < ulStoppedTimerCompensation ) || ( ulCalculatedLoadValue > ulTimerCountsForOneTick ) )

+			{

+				ulCalculatedLoadValue = ( ulTimerCountsForOneTick - 1UL );

+			}

+

+			portNVIC_SYSTICK_LOAD_REG = ulCalculatedLoadValue;

+

+			/* As the pending tick will be processed as soon as this

+			function exits, the tick value maintained by the tick is stepped

+			forward by one less than the time spent waiting. */

+			ulCompleteTickPeriods = xExpectedIdleTime - 1UL;

+		}

+		else

+		{

+			/* Something other than the tick interrupt ended the sleep.

+			Work out how long the sleep lasted rounded to complete tick

+			periods (not the ulReload value which accounted for part

+			ticks). */

+			ulCompletedSysTickDecrements = ( xExpectedIdleTime * ulTimerCountsForOneTick ) - portNVIC_SYSTICK_CURRENT_VALUE_REG ;

+

+			/* How many complete tick periods passed while the processor

+			was waiting? */

+			ulCompleteTickPeriods = ulCompletedSysTickDecrements / ulTimerCountsForOneTick;

+

+			/* The reload value is set to whatever fraction of a single tick

+			period remains. */

+			portNVIC_SYSTICK_LOAD_REG = ( ( ulCompleteTickPeriods + 1UL ) * ulTimerCountsForOneTick ) - ulCompletedSysTickDecrements;

+		}

+

+		/* Restart SysTick so it runs from portNVIC_SYSTICK_LOAD_REG

+		again, then set portNVIC_SYSTICK_LOAD_REG back to its standard

+		value. */

+		portNVIC_SYSTICK_CURRENT_VALUE_REG = 0UL;

+		portNVIC_SYSTICK_CTRL_REG |= portNVIC_SYSTICK_ENABLE_BIT;

+		vTaskStepTick( ulCompleteTickPeriods );

+		portNVIC_SYSTICK_LOAD_REG = ulTimerCountsForOneTick - 1UL;

+

+		/* Exit with interrpts enabled. */

+		__enable_interrupt();

+	}

+}

+

+#endif /* configUSE_TICKLESS_IDLE */

diff --git a/FreeRTOS/Source/portable/IAR/ARM_CM0/portmacro.h b/FreeRTOS/Source/portable/IAR/ARM_CM0/portmacro.h
index 11f362c4d..8103f9cc1 100644
--- a/FreeRTOS/Source/portable/IAR/ARM_CM0/portmacro.h
+++ b/FreeRTOS/Source/portable/IAR/ARM_CM0/portmacro.h
@@ -103,6 +103,13 @@ extern void vClearInterruptMaskFromISR( uint32_t ulMask );
 

 /*-----------------------------------------------------------*/

 

+/* Tickless idle/low power functionality. */

+#ifndef portSUPPRESS_TICKS_AND_SLEEP

+	extern void vPortSuppressTicksAndSleep( TickType_t xExpectedIdleTime );

+	#define portSUPPRESS_TICKS_AND_SLEEP( xExpectedIdleTime ) vPortSuppressTicksAndSleep( xExpectedIdleTime )

+#endif

+/*-----------------------------------------------------------*/

+

 /* Task function macros as described on the FreeRTOS.org WEB site. */

 #define portTASK_FUNCTION_PROTO( vFunction, pvParameters ) void vFunction( void *pvParameters )

 #define portTASK_FUNCTION( vFunction, pvParameters ) void vFunction( void *pvParameters )

diff --git a/FreeRTOS/Source/portable/RVDS/ARM_CM0/port.c b/FreeRTOS/Source/portable/RVDS/ARM_CM0/port.c
index 646dd8e61..8282984b5 100644
--- a/FreeRTOS/Source/portable/RVDS/ARM_CM0/port.c
+++ b/FreeRTOS/Source/portable/RVDS/ARM_CM0/port.c
@@ -34,22 +34,33 @@
 #include "task.h"

 

 /* Constants required to manipulate the NVIC. */

-#define portNVIC_SYSTICK_CTRL			( ( volatile uint32_t * ) 0xe000e010 )

-#define portNVIC_SYSTICK_LOAD			( ( volatile uint32_t * ) 0xe000e014 )

-#define portNVIC_SYSTICK_CURRENT_VALUE	( ( volatile uint32_t * ) 0xe000e018 )

-#define portNVIC_INT_CTRL			( ( volatile uint32_t *) 0xe000ed04 )

-#define portNVIC_SYSPRI2			( ( volatile uint32_t *) 0xe000ed20 )

-#define portNVIC_SYSTICK_CLK		0x00000004

-#define portNVIC_SYSTICK_INT		0x00000002

-#define portNVIC_SYSTICK_ENABLE		0x00000001

-#define portNVIC_PENDSVSET			0x10000000

-#define portMIN_INTERRUPT_PRIORITY	( 255UL )

-#define portNVIC_PENDSV_PRI			( portMIN_INTERRUPT_PRIORITY << 16UL )

-#define portNVIC_SYSTICK_PRI		( portMIN_INTERRUPT_PRIORITY << 24UL )

+#define portNVIC_SYSTICK_CTRL_REG			( * ( ( volatile uint32_t * ) 0xe000e010 ) )

+#define portNVIC_SYSTICK_LOAD_REG			( * ( ( volatile uint32_t * ) 0xe000e014 ) )

+#define portNVIC_SYSTICK_CURRENT_VALUE_REG	( * ( ( volatile uint32_t * ) 0xe000e018 ) )

+#define portNVIC_INT_CTRL_REG				( * ( ( volatile uint32_t * ) 0xe000ed04 ) )

+#define portNVIC_SYSPRI2_REG				( * ( ( volatile uint32_t * ) 0xe000ed20 ) )

+#define portNVIC_SYSTICK_CLK_BIT			( 1UL << 2UL )

+#define portNVIC_SYSTICK_INT_BIT			( 1UL << 1UL )

+#define portNVIC_SYSTICK_ENABLE_BIT			( 1UL << 0UL )

+#define portNVIC_SYSTICK_COUNT_FLAG_BIT		( 1UL << 16UL )

+#define portNVIC_PENDSVSET_BIT				( 1UL << 28UL )

+#define portMIN_INTERRUPT_PRIORITY			( 255UL )

+#define portNVIC_PENDSV_PRI					( portMIN_INTERRUPT_PRIORITY << 16UL )

+#define portNVIC_SYSTICK_PRI				( portMIN_INTERRUPT_PRIORITY << 24UL )

 

 /* Constants required to set up the initial stack. */

 #define portINITIAL_XPSR			( 0x01000000 )

 

+/* The systick is a 24-bit counter. */

+#define portMAX_24_BIT_NUMBER		( 0xffffffUL )

+

+/* A fiddle factor to estimate the number of SysTick counts that would have

+ occurred while the SysTick counter is stopped during tickless idle

+ calculations. */

+#ifndef portMISSED_COUNTS_FACTOR

+	#define portMISSED_COUNTS_FACTOR	( 45UL )

+#endif

+

 /* Constants used with memory barrier intrinsics. */

 #define portSY_FULL_READ_WRITE		( 15 )

 

@@ -57,6 +68,24 @@
 variable. */

 static UBaseType_t uxCriticalNesting = 0xaaaaaaaa;

 

+/* The number of SysTick increments that make up one tick period. */

+#if( configUSE_TICKLESS_IDLE == 1 )

+	static uint32_t ulTimerCountsForOneTick = 0;

+#endif /* configUSE_TICKLESS_IDLE */

+

+/* The maximum number of tick periods that can be suppressed is limited by the

+ 24 bit resolution of the SysTick timer. */

+#if( configUSE_TICKLESS_IDLE == 1 )

+	static uint32_t xMaximumPossibleSuppressedTicks = 0;

+#endif /* configUSE_TICKLESS_IDLE */

+

+ /* Compensate for the CPU cycles that pass while the SysTick is stopped (low

+ power functionality only.

+*/

+#if( configUSE_TICKLESS_IDLE == 1 )

+	static uint32_t ulStoppedTimerCompensation = 0;

+#endif /* configUSE_TICKLESS_IDLE */

+

 /*

  * Setup the timer to generate the tick interrupts.

  */

@@ -158,8 +187,8 @@ __asm void prvPortStartFirstTask( void )
 BaseType_t xPortStartScheduler( void )

 {

 	/* Make PendSV, CallSV and SysTick the same priority as the kernel. */

-	*(portNVIC_SYSPRI2) |= portNVIC_PENDSV_PRI;

-	*(portNVIC_SYSPRI2) |= portNVIC_SYSTICK_PRI;

+	portNVIC_SYSPRI2_REG |= portNVIC_PENDSV_PRI;

+	portNVIC_SYSPRI2_REG |= portNVIC_SYSTICK_PRI;

 

 	/* Start the timer that generates the tick ISR.  Interrupts are disabled

 	here already. */

@@ -187,7 +216,7 @@ void vPortEndScheduler( void )
 void vPortYield( void )

 {

 	/* Set a PendSV to request a context switch. */

-	*( portNVIC_INT_CTRL ) = portNVIC_PENDSVSET;

+	portNVIC_INT_CTRL_REG = portNVIC_PENDSVSET_BIT;

 

 	/* Barriers are normally not required but do ensure the code is completely

 	within the specified behaviour for the architecture. */

@@ -287,7 +316,7 @@ uint32_t ulPreviousMask;
 		if( xTaskIncrementTick() != pdFALSE )

 		{

 			/* Pend a context switch. */

-			*(portNVIC_INT_CTRL) = portNVIC_PENDSVSET;

+			portNVIC_INT_CTRL_REG = portNVIC_PENDSVSET_BIT;

 		}

 	}

 	portCLEAR_INTERRUPT_MASK_FROM_ISR( ulPreviousMask );

@@ -300,13 +329,187 @@ uint32_t ulPreviousMask;
  */

 void prvSetupTimerInterrupt( void )

 {

+	/* Calculate the constants required to configure the tick interrupt. */

+	#if( configUSE_TICKLESS_IDLE == 1 )

+		ulTimerCountsForOneTick = ( configCPU_CLOCK_HZ / configTICK_RATE_HZ );

+		xMaximumPossibleSuppressedTicks = portMAX_24_BIT_NUMBER / ulTimerCountsForOneTick;

+		ulStoppedTimerCompensation = portMISSED_COUNTS_FACTOR;

+	#endif /* configUSE_TICKLESS_IDLE */

+

 	/* Stop and reset the SysTick. */

-	*(portNVIC_SYSTICK_CTRL) = 0UL;

-	*(portNVIC_SYSTICK_CURRENT_VALUE) = 0UL;

+	portNVIC_SYSTICK_CTRL_REG = 0UL;

+	portNVIC_SYSTICK_CURRENT_VALUE_REG = 0UL;

 

 	/* Configure SysTick to interrupt at the requested rate. */

-	*(portNVIC_SYSTICK_LOAD) = ( configCPU_CLOCK_HZ / configTICK_RATE_HZ ) - 1UL;

-	*(portNVIC_SYSTICK_CTRL) = portNVIC_SYSTICK_CLK | portNVIC_SYSTICK_INT | portNVIC_SYSTICK_ENABLE;

+	portNVIC_SYSTICK_LOAD_REG = ( configCPU_CLOCK_HZ / configTICK_RATE_HZ ) - 1UL;

+	portNVIC_SYSTICK_CTRL_REG = portNVIC_SYSTICK_CLK_BIT | portNVIC_SYSTICK_INT_BIT | portNVIC_SYSTICK_ENABLE_BIT;

 }

 /*-----------------------------------------------------------*/

 

+#if( configUSE_TICKLESS_IDLE == 1 )

+

+__weak void vPortSuppressTicksAndSleep( TickType_t xExpectedIdleTime )

+{

+uint32_t ulReloadValue, ulCompleteTickPeriods, ulCompletedSysTickDecrements;

+TickType_t xModifiableIdleTime;

+

+	/* Make sure the SysTick reload value does not overflow the counter. */

+	if( xExpectedIdleTime > xMaximumPossibleSuppressedTicks )

+	{

+		xExpectedIdleTime = xMaximumPossibleSuppressedTicks;

+	}

+

+	/* Stop the SysTick momentarily. The time the SysTick is stopped for

+	is accounted for as best it can be, but using the tickless mode will

+	inevitably result in some tiny drift of the time maintained by the

+	kernel with respect to calendar time. */

+	portNVIC_SYSTICK_CTRL_REG &= ~portNVIC_SYSTICK_ENABLE_BIT;

+

+	/* Calculate the reload value required to wait xExpectedIdleTime

+	tick periods.  -1 is used because this code will execute part way

+	through one of the tick periods. */

+	ulReloadValue = portNVIC_SYSTICK_CURRENT_VALUE_REG + ( ulTimerCountsForOneTick * ( xExpectedIdleTime - 1UL ) );

+	if( ulReloadValue > ulStoppedTimerCompensation )

+	{

+		ulReloadValue -= ulStoppedTimerCompensation;

+	}

+

+	/* Enter a critical section but don't use the taskENTER_CRITICAL()

+	method as that will mask interrupts that should exit sleep mode. */

+	__disable_irq();

+	__dsb( portSY_FULL_READ_WRITE );

+	__isb( portSY_FULL_READ_WRITE );

+

+	/* If a context switch is pending or a task is waiting for the scheduler

+	to be unsuspended then abandon the low power entry. */

+	if( eTaskConfirmSleepModeStatus() == eAbortSleep )

+	{

+		/* Restart from whatever is left in the count register to complete

+		this tick period. */

+		portNVIC_SYSTICK_LOAD_REG = portNVIC_SYSTICK_CURRENT_VALUE_REG;

+

+		/* Restart SysTick. */

+		portNVIC_SYSTICK_CTRL_REG |= portNVIC_SYSTICK_ENABLE_BIT;

+

+		/* Reset the reload register to the value required for normal tick

+		periods. */

+		portNVIC_SYSTICK_LOAD_REG = ulTimerCountsForOneTick - 1UL;

+

+		/* Re-enable interrupts - see comments above __disable_irq() call

+		above. */

+		__enable_irq();

+	}

+	else

+	{

+		/* Set the new reload value. */

+		portNVIC_SYSTICK_LOAD_REG = ulReloadValue;

+

+		/* Clear the SysTick count flag and set the count value back to

+		zero. */

+		portNVIC_SYSTICK_CURRENT_VALUE_REG = 0UL;

+

+		/* Restart SysTick. */

+		portNVIC_SYSTICK_CTRL_REG |= portNVIC_SYSTICK_ENABLE_BIT;

+

+		/* Sleep until something happens. configPRE_SLEEP_PROCESSING() can

+		set its parameter to 0 to indicate that its implementation contains

+		its own wait for interrupt or wait for event instruction, and so wfi

+		should not be executed again. However, the original expected idle

+		time variable must remain unmodified, so a copy is taken. */

+		xModifiableIdleTime = xExpectedIdleTime;

+		configPRE_SLEEP_PROCESSING( xModifiableIdleTime );

+		if( xModifiableIdleTime > 0 )

+		{

+			__dsb( portSY_FULL_READ_WRITE );

+			__wfi();

+			__isb( portSY_FULL_READ_WRITE );

+		}

+		configPOST_SLEEP_PROCESSING( xExpectedIdleTime );

+

+		/* Re-enable interrupts to allow the interrupt that brought the MCU

+		out of sleep mode to execute immediately. see comments above

+		__disable_interrupt() call above. */

+		__enable_irq();

+		__dsb( portSY_FULL_READ_WRITE );

+		__isb( portSY_FULL_READ_WRITE );

+

+		/* Disable interrupts again because the clock is about to be stopped

+		and interrupts that execute while the clock is stopped will increase

+		any slippage between the time maintained by the RTOS and calendar

+		time. */

+		__disable_irq();

+		__dsb( portSY_FULL_READ_WRITE );

+		__isb( portSY_FULL_READ_WRITE );

+

+		/* Disable the SysTick clock without reading the

+		portNVIC_SYSTICK_CTRL_REG register to ensure the

+		portNVIC_SYSTICK_COUNT_FLAG_BIT is not cleared if it is set.  Again,

+		the time the SysTick is stopped for is accounted for as best it can

+		be, but using the tickless mode will inevitably result in some tiny

+		drift of the time maintained by the kernel with respect to calendar

+		time*/

+		portNVIC_SYSTICK_CTRL_REG = ( portNVIC_SYSTICK_CLK_BIT | portNVIC_SYSTICK_INT_BIT );

+

+		/* Determine if the SysTick clock has already counted to zero and

+		been set back to the current reload value (the reload back being

+		correct for the entire expected idle time) or if the SysTick is yet

+		to count to zero (in which case an interrupt other than the SysTick

+		must have brought the system out of sleep mode). */

+		if( ( portNVIC_SYSTICK_CTRL_REG & portNVIC_SYSTICK_COUNT_FLAG_BIT ) != 0 )

+		{

+			uint32_t ulCalculatedLoadValue;

+

+			/* The tick interrupt is already pending, and the SysTick count

+			reloaded with ulReloadValue.  Reset the

+			portNVIC_SYSTICK_LOAD with whatever remains of this tick

+			period. */

+			ulCalculatedLoadValue = ( ulTimerCountsForOneTick - 1UL ) - ( ulReloadValue - portNVIC_SYSTICK_CURRENT_VALUE_REG );

+

+			/* Don't allow a tiny value, or values that have somehow

+			underflowed because the post sleep hook did something

+			that took too long. */

+			if( ( ulCalculatedLoadValue < ulStoppedTimerCompensation ) || ( ulCalculatedLoadValue > ulTimerCountsForOneTick ) )

+			{

+				ulCalculatedLoadValue = ( ulTimerCountsForOneTick - 1UL );

+			}

+

+			portNVIC_SYSTICK_LOAD_REG = ulCalculatedLoadValue;

+

+			/* As the pending tick will be processed as soon as this

+			function exits, the tick value maintained by the tick is stepped

+			forward by one less than the time spent waiting. */

+			ulCompleteTickPeriods = xExpectedIdleTime - 1UL;

+		}

+		else

+		{

+			/* Something other than the tick interrupt ended the sleep.

+			Work out how long the sleep lasted rounded to complete tick

+			periods (not the ulReload value which accounted for part

+			ticks). */

+			ulCompletedSysTickDecrements = ( xExpectedIdleTime * ulTimerCountsForOneTick ) - portNVIC_SYSTICK_CURRENT_VALUE_REG;

+

+			/* How many complete tick periods passed while the processor

+			was waiting? */

+			ulCompleteTickPeriods = ulCompletedSysTickDecrements / ulTimerCountsForOneTick;

+

+			/* The reload value is set to whatever fraction of a single tick

+			period remains. */

+			portNVIC_SYSTICK_LOAD_REG = ( ( ulCompleteTickPeriods + 1UL ) * ulTimerCountsForOneTick ) - ulCompletedSysTickDecrements;

+		}

+

+		/* Restart SysTick so it runs from portNVIC_SYSTICK_LOAD

+		again, then set portNVIC_SYSTICK_LOAD back to its standard

+		value. */

+		portNVIC_SYSTICK_CURRENT_VALUE_REG = 0UL;

+		portNVIC_SYSTICK_CTRL_REG |= portNVIC_SYSTICK_ENABLE_BIT;

+		vTaskStepTick( ulCompleteTickPeriods );

+		portNVIC_SYSTICK_LOAD_REG = ulTimerCountsForOneTick - 1UL;

+

+		/* Exit with interrpts enabled. */

+		__enable_irq();

+	}

+}

+

+#endif /* #if configUSE_TICKLESS_IDLE */

+

+/*-----------------------------------------------------------*/

diff --git a/FreeRTOS/Source/portable/RVDS/ARM_CM0/portmacro.h b/FreeRTOS/Source/portable/RVDS/ARM_CM0/portmacro.h
index 44e7567d8..5f3b9f44e 100644
--- a/FreeRTOS/Source/portable/RVDS/ARM_CM0/portmacro.h
+++ b/FreeRTOS/Source/portable/RVDS/ARM_CM0/portmacro.h
@@ -100,6 +100,13 @@ extern void vClearInterruptMaskFromISR( uint32_t ulMask );
 

 /*-----------------------------------------------------------*/

 

+/* Tickless idle/low power functionality. */

+#ifndef portSUPPRESS_TICKS_AND_SLEEP

+	extern void vPortSuppressTicksAndSleep( TickType_t xExpectedIdleTime );

+	#define portSUPPRESS_TICKS_AND_SLEEP( xExpectedIdleTime ) vPortSuppressTicksAndSleep( xExpectedIdleTime )

+#endif

+/*-----------------------------------------------------------*/

+

 /* Task function macros as described on the FreeRTOS.org WEB site. */

 #define portTASK_FUNCTION_PROTO( vFunction, pvParameters ) void vFunction( void *pvParameters )

 #define portTASK_FUNCTION( vFunction, pvParameters ) void vFunction( void *pvParameters )