/* FreeRTOS V8.0.0 - Copyright (C) 2014 Real Time Engineers Ltd. All rights reserved VISIT http://www.FreeRTOS.org TO ENSURE YOU ARE USING THE LATEST VERSION. *************************************************************************** * * * FreeRTOS provides completely free yet professionally developed, * * robust, strictly quality controlled, supported, and cross * * platform software that has become a de facto standard. * * * * Help yourself get started quickly and support the FreeRTOS * * project by purchasing a FreeRTOS tutorial book, reference * * manual, or both from: http://www.FreeRTOS.org/Documentation * * * * Thank you! * * * *************************************************************************** This file is part of the FreeRTOS distribution. FreeRTOS is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License (version 2) as published by the Free Software Foundation >>!AND MODIFIED BY!<< the FreeRTOS exception. >>! NOTE: The modification to the GPL is included to allow you to distribute >>! a combined work that includes FreeRTOS without being obliged to provide >>! the source code for proprietary components outside of the FreeRTOS >>! kernel. FreeRTOS 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. Full license text is available from the following link: http://www.freertos.org/a00114.html 1 tab == 4 spaces! *************************************************************************** * * * Having a problem? Start by reading the FAQ "My application does * * not run, what could be wrong?" * * * * http://www.FreeRTOS.org/FAQHelp.html * * * *************************************************************************** http://www.FreeRTOS.org - Documentation, books, training, latest versions, license and Real Time Engineers Ltd. contact details. http://www.FreeRTOS.org/plus - A selection of FreeRTOS ecosystem products, including FreeRTOS+Trace - an indispensable productivity tool, a DOS compatible FAT file system, and our tiny thread aware UDP/IP stack. http://www.OpenRTOS.com - Real Time Engineers ltd license FreeRTOS to High Integrity Systems to sell under the OpenRTOS brand. Low cost OpenRTOS licenses offer ticketed support, indemnification and middleware. http://www.SafeRTOS.com - High Integrity Systems also provide a safety engineered and independently SIL3 certified version for use in safety and mission critical applications that require provable dependability. 1 tab == 4 spaces! */ #ifndef EVENT_GROUPS_H #define EVENT_GROUPS_H #ifndef INC_FREERTOS_H #error "include FreeRTOS.h" must appear in source files before "include event_groups.h" #endif #include "timers.h" #ifdef __cplusplus extern "C" { #endif /** * An event group is a collection of bits to which an application can assign a * meaning. For example, an application may create an event group to convey * the status of various CAN bus related events in which bit 0 might mean "A CAN * message has been received and is ready for processing", bit 1 might mean "The * application has queued a message that is ready for sending onto the CAN * network", and bit 2 might mean "It is time to send a SYNC message onto the * CAN network" etc. A task can then test the bit values to see which events * are active, and optionally enter the Blocked state to wait for a specified * bit or a group of specified bits to be active. To continue the CAN bus * example, a CAN controlling task can enter the Blocked state (and therefore * not consume any processing time) until either bit 0, bit 1 or bit 2 are * active, at which time the bit that was actually active would inform the task * which action it had to take (process a received message, send a message, or * send a SYNC). * * The event groups implementation contains intelligence to avoid race * conditions that would otherwise occur were an application to use a simple * variable for the same purpose. This is particularly important with respect * to when a bit within an event group is to be cleared, and when bits have to * be set and then tested atomically - as is the case where event groups are * used to create a synchronisation point between multiple tasks (a * 'rendezvous'). * * \defgroup EventGroup */ /** * event_groups.h * * Type by which event groups are referenced. For example, a call to * xEventGroupCreate() returns an EventGroupHandle_t variable that can then * be used as a parameter to other event group functions. * * \defgroup EventGroupHandle_t EventGroupHandle_t * \ingroup EventGroup */ typedef void * EventGroupHandle_t; /* * The type that holds event bits always matches TickType_t - therefore the * number of bits it holds is set by configUSE_16_BIT_TICKS (16 bits if set to 1, * 32 bits if set to 0. * * \defgroup EventBits_t EventBits_t * \ingroup EventGroup */ typedef TickType_t EventBits_t; /** * event_groups.h *
EventGroupHandle_t xEventGroupCreate( void );* * Create a new event group. This function cannot be called from an interrupt. * * Although event groups are not related to ticks, for internal implementation * reasons the number of bits available for use in an event group is dependent * on the configUSE_16_BIT_TICKS setting in FreeRTOSConfig.h. If * configUSE_16_BIT_TICKS is 1 then each event group contains 8 usable bits (bit * 0 to bit 7). If configUSE_16_BIT_TICKS is set to 0 then each event group has * 24 usable bits (bit 0 to bit 23). The EventBits_t type is used to store * event bits within an event group. * * @return If the event group was created then a handle to the event group is * returned. If there was insufficient FreeRTOS heap available to create the * event group then NULL is returned. See http://www.freertos.org/a00111.html * * Example usage:
// Declare a variable to hold the created event group. EventGroupHandle_t xCreatedEventGroup; // Attempt to create the event group. xCreatedEventGroup = xEventGroupCreate(); // Was the event group created successfully? if( xCreatedEventGroup == NULL ) { // The event group was not created because there was insufficient // FreeRTOS heap available. } else { // The event group was created. }* \defgroup xEventGroupCreate xEventGroupCreate * \ingroup EventGroup */ EventGroupHandle_t xEventGroupCreate( void ) PRIVILEGED_FUNCTION; /** * event_groups.h *
EventBits_t xEventGroupWaitBits( EventGroupHandle_t xEventGroup, const EventBits_t uxBitsToWaitFor, const BaseType_t xClearOnExit, const BaseType_t xWaitForAllBits, const TickType_t xTicksToWait );* * [Potentially] block to wait for one or more bits to be set within a * previously created event group. * * This function cannot be called from an interrupt. * * @param xEventGroup The event group in which the bits are being tested. The * event group must have previously been created using a call to * xEventGroupCreate(). * * @param uxBitsToWaitFor A bitwise value that indicates the bit or bits to test * inside the event group. For example, to wait for bit 0 and/or bit 2 set * uxBitsToWaitFor to 0x05. To wait for bits 0 and/or bit 1 and/or bit 2 set * uxBitsToWaitFor to 0x07. Etc. * * @param xClearOnExit If xClearOnExit is set to pdTRUE then any bits within * uxBitsToWaitFor that are set within the event group will be cleared before * xEventGroupWaitBits() returns if the wait condition was met (if the function * returns for a reason other than a timeout). If xClearOnExit is set to * pdFALSE then the bits set in the event group are not altered when the call to * xEventGroupWaitBits() returns. * * @param xWaitForAllBits If xWaitForAllBits is set to pdTRUE then * xEventGroupWaitBits() will return when either all the bits in uxBitsToWaitFor * are set or the specified block time expires. If xWaitForAllBits is set to * pdFALSE then xEventGroupWaitBits() will return when any one of the bits set * in uxBitsToWaitFor is set or the specified block time expires. The block * time is specified by the xTicksToWait parameter. * * @param xTicksToWait The maximum amount of time (specified in 'ticks') to wait * for one/all (depending on the xWaitForAllBits value) of the bits specified by * uxBitsToWaitFor to become set. * * @return The value of the event group at the time either the bits being waited * for became set, or the block time expired. Test the return value to know * which bits were set. If xEventGroupWaitBits() returned because its timeout * expired then not all the bits being waited for will be set. If * xEventGroupWaitBits() returned because the bits it was waiting for were set * then the returned value is the event group value before any bits were * automatically cleared in the case that xClearOnExit parameter was set to * pdTRUE. * * Example usage:
#define BIT_0 ( 1 << 0 ) #define BIT_4 ( 1 << 4 ) void aFunction( EventGroupHandle_t xEventGroup ) { EventBits_t uxBits; const TickType_t xTicksToWait = 100 / portTICK_PERIOD_MS; // Wait a maximum of 100ms for either bit 0 or bit 4 to be set within // the event group. Clear the bits before exiting. uxBits = xEventGroupWaitBits( xEventGroup, // The event group being tested. BIT_0 | BIT_4, // The bits within the event group to wait for. pdTRUE, // BIT_0 and BIT_4 should be cleared before returning. pdFALSE, // Don't wait for both bits, either bit will do. xTicksToWait ); // Wait a maximum of 100ms for either bit to be set. if( ( uxBits & ( BIT_0 | BIT_4 ) ) == ( BIT_0 | BIT_4 ) ) { // xEventGroupWaitBits() returned because both bits were set. } else if( ( uxBits & BIT_0 ) != 0 ) { // xEventGroupWaitBits() returned because just BIT_0 was set. } else if( ( uxBits & BIT_4 ) != 0 ) { // xEventGroupWaitBits() returned because just BIT_4 was set. } else { // xEventGroupWaitBits() returned because xTicksToWait ticks passed // without either BIT_0 or BIT_4 becoming set. } }* \defgroup xEventGroupWaitBits xEventGroupWaitBits * \ingroup EventGroup */ EventBits_t xEventGroupWaitBits( EventGroupHandle_t xEventGroup, const EventBits_t uxBitsToWaitFor, const BaseType_t xClearOnExit, const BaseType_t xWaitForAllBits, TickType_t xTicksToWait ) PRIVILEGED_FUNCTION; /** * event_groups.h *
EventBits_t xEventGroupClearBits( EventGroupHandle_t xEventGroup, const EventBits_t uxBitsToClear );* * Clear bits within an event group. This function cannot be called from an * interrupt. * * @param xEventGroup The event group in which the bits are to be cleared. * * @param uxBitsToClear A bitwise value that indicates the bit or bits to clear * in the event group. For example, to clear bit 3 only, set uxBitsToClear to * 0x08. To clear bit 3 and bit 0 set uxBitsToClear to 0x09. * * @return The value of the event group before the specified bits were cleared. * * Example usage:
#define BIT_0 ( 1 << 0 ) #define BIT_4 ( 1 << 4 ) void aFunction( EventGroupHandle_t xEventGroup ) { EventBits_t uxBits; // Clear bit 0 and bit 4 in xEventGroup. uxBits = xEventGroupClearBits( xEventGroup, // The event group being updated. BIT_0 | BIT_4 );// The bits being cleared. if( ( uxBits & ( BIT_0 | BIT_4 ) ) == ( BIT_0 | BIT_4 ) ) { // Both bit 0 and bit 4 were set before xEventGroupClearBits() was // called. Both will now be clear (not set). } else if( ( uxBits & BIT_0 ) != 0 ) { // Bit 0 was set before xEventGroupClearBits() was called. It will // now be clear. } else if( ( uxBits & BIT_4 ) != 0 ) { // Bit 4 was set before xEventGroupClearBits() was called. It will // now be clear. } else { // Neither bit 0 nor bit 4 were set in the first place. } }* \defgroup xEventGroupClearBits xEventGroupClearBits * \ingroup EventGroup */ EventBits_t xEventGroupClearBits( EventGroupHandle_t xEventGroup, const EventBits_t uxBitsToClear ) PRIVILEGED_FUNCTION; /** * event_groups.h *
EventBits_t xEventGroupClearBitsFromISR( EventGroupHandle_t xEventGroup, const EventBits_t uxBitsToClear );* * A version of xEventGroupClearBits() that can be called from an interrupt * service routine. See the xEventGroupClearBits() documentation. * * \defgroup xEventGroupClearBitsFromISR xEventGroupClearBitsFromISR * \ingroup EventGroup */ EventBits_t xEventGroupClearBitsFromISR( EventGroupHandle_t xEventGroup, const EventBits_t uxBitsToClear ) PRIVILEGED_FUNCTION; /** * event_groups.h *
EventBits_t xEventGroupSetBits( EventGroupHandle_t xEventGroup, const EventBits_t uxBitsToSet );* * Set bits within an event group. * This function cannot be called from an interrupt. xEventGroupSetBitsFromISR() * is a version that can be called from an interrupt. * * Setting bits in an event group will automatically unblock tasks that are * blocked waiting for the bits. * * @param xEventGroup The event group in which the bits are to be set. * * @param uxBitsToSet A bitwise value that indicates the bit or bits to set. * For example, to set bit 3 only, set uxBitsToSet to 0x08. To set bit 3 * and bit 0 set uxBitsToSet to 0x09. * * @return The value of the event group at the time the call to * xEventGroupSetBits() returns. There are two reasons why the returned value * might have the bits specified by the uxBitsToSet parameter cleared. First, * if setting a bit results in a task that was waiting for the bit leaving the * blocked state then it is possible the bit will be cleared automatically * (see the xClearBitOnExit parameter of xEventGroupWaitBits()). Second, any * unblocked (or otherwise Ready state) task that has a priority above that of * the task that called xEventGroupSetBits() will execute and may change the * event group value before the call to xEventGroupSetBits() returns. * * Example usage:
#define BIT_0 ( 1 << 0 ) #define BIT_4 ( 1 << 4 ) void aFunction( EventGroupHandle_t xEventGroup ) { EventBits_t uxBits; // Set bit 0 and bit 4 in xEventGroup. uxBits = xEventGroupSetBits( xEventGroup, // The event group being updated. BIT_0 | BIT_4 );// The bits being set. if( ( uxBits & ( BIT_0 | BIT_4 ) ) == ( BIT_0 | BIT_4 ) ) { // Both bit 0 and bit 4 remained set when the function returned. } else if( ( uxBits & BIT_0 ) != 0 ) { // Bit 0 remained set when the function returned, but bit 4 was // cleared. It might be that bit 4 was cleared automatically as a // task that was waiting for bit 4 was removed from the Blocked // state. } else if( ( uxBits & BIT_4 ) != 0 ) { // Bit 4 remained set when the function returned, but bit 0 was // cleared. It might be that bit 0 was cleared automatically as a // task that was waiting for bit 0 was removed from the Blocked // state. } else { // Neither bit 0 nor bit 4 remained set. It might be that a task // was waiting for both of the bits to be set, and the bits were // cleared as the task left the Blocked state. } }* \defgroup xEventGroupSetBits xEventGroupSetBits * \ingroup EventGroup */ EventBits_t xEventGroupSetBits( EventGroupHandle_t xEventGroup, const EventBits_t uxBitsToSet ) PRIVILEGED_FUNCTION; /** * event_groups.h *
BaseType_t xEventGroupSetBitsFromISR( EventGroupHandle_t xEventGroup, const EventBits_t uxBitsToSet, BaseType_t *pxHigherPriorityTaskWoken );* * A version of xEventGroupSetBits() that can be called from an interrupt. * * Setting bits in an event group is not a deterministic operation because there * are an unknown number of tasks that may be waiting for the bit or bits being * set. FreeRTOS does not allow nondeterministic operations to be performed in * interrupts or from critical sections. Therefore xEventGroupSetBitFromISR() * sends a message to the timer task to have the set operation performed in the * context of the timer task - where a scheduler lock is used in place of a * critical section. * * @param xEventGroup The event group in which the bits are to be set. * * @param uxBitsToSet A bitwise value that indicates the bit or bits to set. * For example, to set bit 3 only, set uxBitsToSet to 0x08. To set bit 3 * and bit 0 set uxBitsToSet to 0x09. * * @param pxHigherPriorityTaskWoken As mentioned above, calling this function * will result in a message being sent to the timer daemon task. If the * priority of the timer daemon task is higher than the priority of the * currently running task (the task the interrupt interrupted) then * *pxHigherPriorityTaskWoken will be set to pdTRUE by * xEventGroupSetBitsFromISR(), indicating that a context switch should be * requested before the interrupt exits. For that reason * *pxHigherPriorityTaskWoken must be initialised to pdFALSE. See the * example code below. * * @return If the request to execute the function was posted successfully then * pdPASS is returned, otherwise pdFALSE is returned. pdFALSE will be returned * if the timer service queue was full. * * Example usage:
#define BIT_0 ( 1 << 0 ) #define BIT_4 ( 1 << 4 ) // An event group which it is assumed has already been created by a call to // xEventGroupCreate(). EventGroupHandle_t xEventGroup; void anInterruptHandler( void ) { BaseType_t xHigherPriorityTaskWoken, xResult; // xHigherPriorityTaskWoken must be initialised to pdFALSE. xHigherPriorityTaskWoken = pdFALSE; // Set bit 0 and bit 4 in xEventGroup. xResult = xEventGroupSetBitsFromISR( xEventGroup, // The event group being updated. BIT_0 | BIT_4 // The bits being set. &xHigherPriorityTaskWoken ); // Was the message posted successfully? if( xResult == pdPASS ) { // If xHigherPriorityTaskWoken is now set to pdTRUE then a context // switch should be requested. The macro used is port specific and // will be either portYIELD_FROM_ISR() or portEND_SWITCHING_ISR() - // refer to the documentation page for the port being used. portYIELD_FROM_ISR( xHigherPriorityTaskWoken ); } }* \defgroup xEventGroupSetBitsFromISR xEventGroupSetBitsFromISR * \ingroup EventGroup */ #if( configUSE_TRACE_FACILITY == 1 ) BaseType_t xEventGroupSetBitsFromISR( EventGroupHandle_t xEventGroup, const EventBits_t uxBitsToSet, BaseType_t *pxHigherPriorityTaskWoken ); #else #define xEventGroupSetBitsFromISR( xEventGroup, uxBitsToSet, pxHigherPriorityTaskWoken ) xTimerPendFunctionCallFromISR( vEventGroupSetBitsCallback, ( void * ) xEventGroup, ( uint32_t ) uxBitsToSet, pxHigherPriorityTaskWoken ) #endif /** * event_groups.h *
EventBits_t xEventGroupSync( EventGroupHandle_t xEventGroup, const EventBits_t uxBitsToSet, const EventBits_t uxBitsToWaitFor, TickType_t xTicksToWait );* * Atomically set bits within an event group, then wait for a combination of * bits to be set within the same event group. This functionality is typically * used to synchronise multiple tasks, where each task has to wait for the other * tasks to reach a synchronisation point before proceeding. * * This function cannot be used from an interrupt. * * The function will return before its block time expires if the bits specified * by the uxBitsToWait parameter are set, or become set within that time. In * this case all the bits specified by uxBitsToWait will be automatically * cleared before the function returns. * * @param xEventGroup The event group in which the bits are being tested. The * event group must have previously been created using a call to * xEventGroupCreate(). * * @param uxBitsToSet The bits to set in the event group before determining * if, and possibly waiting for, all the bits specified by the uxBitsToWait * parameter are set. * * @param uxBitsToWaitFor A bitwise value that indicates the bit or bits to test * inside the event group. For example, to wait for bit 0 and bit 2 set * uxBitsToWaitFor to 0x05. To wait for bits 0 and bit 1 and bit 2 set * uxBitsToWaitFor to 0x07. Etc. * * @param xTicksToWait The maximum amount of time (specified in 'ticks') to wait * for all of the bits specified by uxBitsToWaitFor to become set. * * @return The value of the event group at the time either the bits being waited * for became set, or the block time expired. Test the return value to know * which bits were set. If xEventGroupSync() returned because its timeout * expired then not all the bits being waited for will be set. If * xEventGroupSync() returned because all the bits it was waiting for were * set then the returned value is the event group value before any bits were * automatically cleared. * * Example usage:
// Bits used by the three tasks. #define TASK_0_BIT ( 1 << 0 ) #define TASK_1_BIT ( 1 << 1 ) #define TASK_2_BIT ( 1 << 2 ) #define ALL_SYNC_BITS ( TASK_0_BIT | TASK_1_BIT | TASK_2_BIT ) // Use an event group to synchronise three tasks. It is assumed this event // group has already been created elsewhere. EventGroupHandle_t xEventBits; void vTask0( void *pvParameters ) { EventBits_t uxReturn; TickType_t xTicksToWait = 100 / portTICK_PERIOD_MS; for( ;; ) { // Perform task functionality here. // Set bit 0 in the event flag to note this task has reached the // sync point. The other two tasks will set the other two bits defined // by ALL_SYNC_BITS. All three tasks have reached the synchronisation // point when all the ALL_SYNC_BITS are set. Wait a maximum of 100ms // for this to happen. uxReturn = xEventGroupSync( xEventBits, TASK_0_BIT, ALL_SYNC_BITS, xTicksToWait ); if( ( uxReturn & ALL_SYNC_BITS ) == ALL_SYNC_BITS ) { // All three tasks reached the synchronisation point before the call // to xEventGroupSync() timed out. } } } void vTask1( void *pvParameters ) { for( ;; ) { // Perform task functionality here. // Set bit 1 in the event flag to note this task has reached the // synchronisation point. The other two tasks will set the other two // bits defined by ALL_SYNC_BITS. All three tasks have reached the // synchronisation point when all the ALL_SYNC_BITS are set. Wait // indefinitely for this to happen. xEventGroupSync( xEventBits, TASK_1_BIT, ALL_SYNC_BITS, portMAX_DELAY ); // xEventGroupSync() was called with an indefinite block time, so // this task will only reach here if the syncrhonisation was made by all // three tasks, so there is no need to test the return value. } } void vTask2( void *pvParameters ) { for( ;; ) { // Perform task functionality here. // Set bit 2 in the event flag to note this task has reached the // synchronisation point. The other two tasks will set the other two // bits defined by ALL_SYNC_BITS. All three tasks have reached the // synchronisation point when all the ALL_SYNC_BITS are set. Wait // indefinitely for this to happen. xEventGroupSync( xEventBits, TASK_2_BIT, ALL_SYNC_BITS, portMAX_DELAY ); // xEventGroupSync() was called with an indefinite block time, so // this task will only reach here if the syncrhonisation was made by all // three tasks, so there is no need to test the return value. } }* \defgroup xEventGroupSync xEventGroupSync * \ingroup EventGroup */ EventBits_t xEventGroupSync( EventGroupHandle_t xEventGroup, const EventBits_t uxBitsToSet, const EventBits_t uxBitsToWaitFor, TickType_t xTicksToWait ) PRIVILEGED_FUNCTION; /** * event_groups.h *
EventBits_t xEventGroupGetBits( EventGroupHandle_t xEventGroup );* * Returns the current value of the bits in an event group. This function * cannot be used from an interrupt. * * @param xEventGroup The event group being queried. * * @return The event group bits at the time xEventGroupGetBits() was called. * * \defgroup xEventGroupGetBits xEventGroupGetBits * \ingroup EventGroup */ #define xEventGroupGetBits( xEventGroup ) xEventGroupClearBits( xEventGroup, 0 ) /** * event_groups.h *
EventBits_t xEventGroupGetBitsFromISR( EventGroupHandle_t xEventGroup );* * A version of xEventGroupGetBits() that can be called from an ISR. * * @param xEventGroup The event group being queried. * * @return The event group bits at the time xEventGroupGetBitsFromISR() was called. * * \defgroup xEventGroupGetBitsFromISR xEventGroupGetBitsFromISR * \ingroup EventGroup */ #define xEventGroupGetBitsFromISR( xEventGroup ) xEventGroupClearBitsFromISR( xEventGroup, 0 ) /** * event_groups.h *
void xEventGroupDelete( EventGroupHandle_t xEventGroup );* * Delete an event group that was previously created by a call to * xEventGroupCreate(). Tasks that are blocked on the event group will be * unblocked and obtain 0 as the event group's value. * * @param xEventGroup The event group being deleted. */ void vEventGroupDelete( EventGroupHandle_t xEventGroup ); /* For internal use only. */ void vEventGroupSetBitsCallback( void *pvEventGroup, const uint32_t ulBitsToSet ); #if (configUSE_TRACE_FACILITY == 1) UBaseType_t uxEventGroupGetNumber( void* xEventGroup ); #endif #ifdef __cplusplus } #endif #endif /* EVENT_GROUPS_H */