#define portINITIAL_EXEC_RETURN ( 0xfffffffd )\r
\r
/* The systick is a 24-bit counter. */\r
-#define portMAX_24_BIT_NUMBER ( 0xffffffUL )\r
+#define portMAX_24_BIT_NUMBER ( 0xffffffUL )\r
\r
/* A fiddle factor to estimate the number of SysTick counts that would have\r
occurred while the SysTick counter is stopped during tickless idle\r
calculations. */\r
-#define portMISSED_COUNTS_FACTOR ( 45UL )\r
+#define portMISSED_COUNTS_FACTOR ( 45UL )\r
\r
/* For strict compliance with the Cortex-M spec the task start address should\r
have bit-0 clear, as it is loaded into the PC on exit from an ISR. */\r
-#define portSTART_ADDRESS_MASK ( ( StackType_t ) 0xfffffffeUL )\r
-\r
-/* Each task maintains its own interrupt status in the critical nesting\r
-variable. */\r
-static UBaseType_t uxCriticalNesting = 0xaaaaaaaa;\r
+#define portSTART_ADDRESS_MASK ( ( StackType_t ) 0xfffffffeUL )\r
\r
/*\r
* Setup the timer to generate the tick interrupts. The implementation in this\r
\r
/*-----------------------------------------------------------*/\r
\r
+/* Each task maintains its own interrupt status in the critical nesting\r
+variable. */\r
+static UBaseType_t uxCriticalNesting = 0xaaaaaaaa;\r
+\r
/*\r
* The number of SysTick increments that make up one tick period.\r
*/\r
-#if configUSE_TICKLESS_IDLE == 1\r
+#if( configUSE_TICKLESS_IDLE == 1 )\r
static uint32_t ulTimerCountsForOneTick = 0;\r
#endif /* configUSE_TICKLESS_IDLE */\r
\r
* The maximum number of tick periods that can be suppressed is limited by the\r
* 24 bit resolution of the SysTick timer.\r
*/\r
-#if configUSE_TICKLESS_IDLE == 1\r
+#if( configUSE_TICKLESS_IDLE == 1 )\r
static uint32_t xMaximumPossibleSuppressedTicks = 0;\r
#endif /* configUSE_TICKLESS_IDLE */\r
\r
* Compensate for the CPU cycles that pass while the SysTick is stopped (low\r
* power functionality only.\r
*/\r
-#if configUSE_TICKLESS_IDLE == 1\r
+#if( configUSE_TICKLESS_IDLE == 1 )\r
static uint32_t ulStoppedTimerCompensation = 0;\r
#endif /* configUSE_TICKLESS_IDLE */\r
\r
}\r
/*-----------------------------------------------------------*/\r
\r
-#if configUSE_TICKLESS_IDLE == 1\r
+#if( configUSE_TICKLESS_IDLE == 1 )\r
\r
__weak void vPortSuppressTicksAndSleep( TickType_t xExpectedIdleTime )\r
{\r
- uint32_t ulReloadValue, ulCompleteTickPeriods, ulCompletedSysTickDecrements, ulSysTickCTRL;\r
+ uint32_t ulReloadValue, ulCompleteTickPeriods, ulCompletedSysTickDecrements;\r
TickType_t xModifiableIdleTime;\r
\r
/* Make sure the SysTick reload value does not overflow the counter. */\r
}\r
configPOST_SLEEP_PROCESSING( xExpectedIdleTime );\r
\r
- /* Stop SysTick. Again, the time the SysTick is stopped for is\r
- accounted for as best it can be, but using the tickless mode will\r
- inevitably result in some tiny drift of the time maintained by the\r
- kernel with respect to calendar time. */\r
- ulSysTickCTRL = portNVIC_SYSTICK_CTRL_REG;\r
- portNVIC_SYSTICK_CTRL_REG = ( ulSysTickCTRL & ~portNVIC_SYSTICK_ENABLE_BIT );\r
-\r
- /* Re-enable interrupts - see comments above __disable_irq() call\r
- above. */\r
+ /* Re-enable interrupts to allow the interrupt that brought the MCU\r
+ out of sleep mode to execute immediately. see comments above\r
+ __disable_interrupt() call above. */\r
__enable_irq();\r
-\r
- if( ( ulSysTickCTRL & portNVIC_SYSTICK_COUNT_FLAG_BIT ) != 0 )\r
+ __dsb( portSY_FULL_READ_WRITE );\r
+ __isb( portSY_FULL_READ_WRITE );\r
+\r
+ /* Disable interrupts again because the clock is about to be stopped\r
+ and interrupts that execute while the clock is stopped will increase\r
+ any slippage between the time maintained by the RTOS and calendar\r
+ time. */\r
+ __disable_irq();\r
+ __dsb( portSY_FULL_READ_WRITE );\r
+ __isb( portSY_FULL_READ_WRITE );\r
+ \r
+ /* Disable the SysTick clock without reading the \r
+ portNVIC_SYSTICK_CTRL_REG register to ensure the\r
+ portNVIC_SYSTICK_COUNT_FLAG_BIT is not cleared if it is set. Again, \r
+ the time the SysTick is stopped for is accounted for as best it can \r
+ be, but using the tickless mode will inevitably result in some tiny \r
+ drift of the time maintained by the kernel with respect to calendar \r
+ time*/\r
+ portNVIC_SYSTICK_CTRL_REG = ( portNVIC_SYSTICK_CLK_BIT | portNVIC_SYSTICK_INT_BIT );\r
+\r
+ /* Determine if the SysTick clock has already counted to zero and\r
+ been set back to the current reload value (the reload back being\r
+ correct for the entire expected idle time) or if the SysTick is yet\r
+ to count to zero (in which case an interrupt other than the SysTick\r
+ must have brought the system out of sleep mode). */\r
+ if( ( portNVIC_SYSTICK_CTRL_REG & portNVIC_SYSTICK_COUNT_FLAG_BIT ) != 0 )\r
{\r
uint32_t ulCalculatedLoadValue;\r
\r
- /* The tick interrupt has already executed, and the SysTick\r
- count reloaded with ulReloadValue. Reset the\r
+ /* The tick interrupt is already pending, and the SysTick count\r
+ reloaded with ulReloadValue. Reset the\r
portNVIC_SYSTICK_LOAD_REG with whatever remains of this tick\r
period. */\r
ulCalculatedLoadValue = ( ulTimerCountsForOneTick - 1UL ) - ( ulReloadValue - portNVIC_SYSTICK_CURRENT_VALUE_REG );\r
\r
portNVIC_SYSTICK_LOAD_REG = ulCalculatedLoadValue;\r
\r
- /* The tick interrupt handler will already have pended the tick\r
- processing in the kernel. As the pending tick will be\r
- processed as soon as this function exits, the tick value\r
- maintained by the tick is stepped forward by one less than the\r
- time spent waiting. */\r
+ /* As the pending tick will be processed as soon as this\r
+ function exits, the tick value maintained by the tick is stepped\r
+ forward by one less than the time spent waiting. */\r
ulCompleteTickPeriods = xExpectedIdleTime - 1UL;\r
}\r
else\r
\r
/* Restart SysTick so it runs from portNVIC_SYSTICK_LOAD_REG\r
again, then set portNVIC_SYSTICK_LOAD_REG back to its standard\r
- value. The critical section is used to ensure the tick interrupt\r
- can only execute once in the case that the reload register is near\r
- zero. */\r
+ value. */\r
portNVIC_SYSTICK_CURRENT_VALUE_REG = 0UL;\r
- portENTER_CRITICAL();\r
- {\r
- portNVIC_SYSTICK_CTRL_REG |= portNVIC_SYSTICK_ENABLE_BIT;\r
- vTaskStepTick( ulCompleteTickPeriods );\r
- portNVIC_SYSTICK_LOAD_REG = ulTimerCountsForOneTick - 1UL;\r
- }\r
- portEXIT_CRITICAL();\r
+ portNVIC_SYSTICK_CTRL_REG |= portNVIC_SYSTICK_ENABLE_BIT;\r
+ vTaskStepTick( ulCompleteTickPeriods );\r
+ portNVIC_SYSTICK_LOAD_REG = ulTimerCountsForOneTick - 1UL;\r
+\r
+ /* Exit with interrpts enabled. */\r
+ __enable_irq();\r
}\r
}\r
\r
* Setup the SysTick timer to generate the tick interrupts at the required\r
* frequency.\r
*/\r
-#if configOVERRIDE_DEFAULT_TICK_CONFIGURATION == 0\r
+#if( configOVERRIDE_DEFAULT_TICK_CONFIGURATION == 0 )\r
\r
void vPortSetupTimerInterrupt( void )\r
{\r
/* Calculate the constants required to configure the tick interrupt. */\r
- #if configUSE_TICKLESS_IDLE == 1\r
+ #if( configUSE_TICKLESS_IDLE == 1 )\r
{\r
ulTimerCountsForOneTick = ( configSYSTICK_CLOCK_HZ / configTICK_RATE_HZ );\r
xMaximumPossibleSuppressedTicks = portMAX_24_BIT_NUMBER / ulTimerCountsForOneTick;\r
devices by calling NVIC_SetPriorityGrouping( 0 ); before starting the\r
scheduler. Note however that some vendor specific peripheral libraries\r
assume a non-zero priority group setting, in which cases using a value\r
- of zero will result in unpredicable behaviour. */\r
+ of zero will result in unpredictable behaviour. */\r
configASSERT( ( portAIRCR_REG & portPRIORITY_GROUP_MASK ) <= ulMaxPRIGROUPValue );\r
}\r
\r
projects / freertos / blobdiff