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diff --git a/contrib/FreeRTOS_Library/include/semphr.h b/contrib/FreeRTOS_Library/include/semphr.h deleted file mode 100644 index 842ee5d..0000000 --- a/contrib/FreeRTOS_Library/include/semphr.h +++ /dev/null @@ -1,711 +0,0 @@ -/*
- FreeRTOS V6.1.0 - Copyright (C) 2010 Real Time Engineers Ltd.
-
- ***************************************************************************
- * *
- * If you are: *
- * *
- * + New to FreeRTOS, *
- * + Wanting to learn FreeRTOS or multitasking in general quickly *
- * + Looking for basic training, *
- * + Wanting to improve your FreeRTOS skills and productivity *
- * *
- * then take a look at the FreeRTOS books - available as PDF or paperback *
- * *
- * "Using the FreeRTOS Real Time Kernel - a Practical Guide" *
- * http://www.FreeRTOS.org/Documentation *
- * *
- * A pdf reference manual is also available. Both are usually delivered *
- * to your inbox within 20 minutes to two hours when purchased between 8am *
- * and 8pm GMT (although please allow up to 24 hours in case of *
- * exceptional circumstances). Thank you for your support! *
- * *
- ***************************************************************************
-
- 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 exception 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. See the GNU General Public License for
- more details. You should have received a copy of the GNU General Public
- License and the FreeRTOS license exception along with FreeRTOS; if not it
- can be viewed here: http://www.freertos.org/a00114.html and also obtained
- by writing to Richard Barry, contact details for whom are available on the
- FreeRTOS WEB site.
-
- 1 tab == 4 spaces!
-
- http://www.FreeRTOS.org - Documentation, latest information, license and
- contact details.
-
- http://www.SafeRTOS.com - A version that is certified for use in safety
- critical systems.
-
- http://www.OpenRTOS.com - Commercial support, development, porting,
- licensing and training services.
-*/
-
-#ifndef INC_FREERTOS_H
- #error "#include FreeRTOS.h" must appear in source files before "#include semphr.h"
-#endif
-
-#ifndef SEMAPHORE_H
-#define SEMAPHORE_H
-
-#include "queue.h"
-
-typedef xQueueHandle xSemaphoreHandle;
-
-#define semBINARY_SEMAPHORE_QUEUE_LENGTH ( ( unsigned char ) 1 )
-#define semSEMAPHORE_QUEUE_ITEM_LENGTH ( ( unsigned char ) 0 )
-#define semGIVE_BLOCK_TIME ( ( portTickType ) 0 )
-
-
-/**
- * semphr. h
- * <pre>vSemaphoreCreateBinary( xSemaphoreHandle xSemaphore )</pre>
- *
- * <i>Macro</i> that implements a semaphore by using the existing queue mechanism.
- * The queue length is 1 as this is a binary semaphore. The data size is 0
- * as we don't want to actually store any data - we just want to know if the
- * queue is empty or full.
- *
- * This type of semaphore can be used for pure synchronisation between tasks or
- * between an interrupt and a task. The semaphore need not be given back once
- * obtained, so one task/interrupt can continuously 'give' the semaphore while
- * another continuously 'takes' the semaphore. For this reason this type of
- * semaphore does not use a priority inheritance mechanism. For an alternative
- * that does use priority inheritance see xSemaphoreCreateMutex().
- *
- * @param xSemaphore Handle to the created semaphore. Should be of type xSemaphoreHandle.
- *
- * Example usage:
- <pre>
- xSemaphoreHandle xSemaphore;
-
- void vATask( void * pvParameters )
- {
- // Semaphore cannot be used before a call to vSemaphoreCreateBinary ().
- // This is a macro so pass the variable in directly.
- vSemaphoreCreateBinary( xSemaphore );
-
- if( xSemaphore != NULL )
- {
- // The semaphore was created successfully.
- // The semaphore can now be used.
- }
- }
- </pre>
- * \defgroup vSemaphoreCreateBinary vSemaphoreCreateBinary
- * \ingroup Semaphores
- */
-#define vSemaphoreCreateBinary( xSemaphore ) { \
- xSemaphore = xQueueCreate( ( unsigned portBASE_TYPE ) 1, semSEMAPHORE_QUEUE_ITEM_LENGTH ); \
- if( xSemaphore != NULL ) \
- { \
- xSemaphoreGive( xSemaphore ); \
- } \
- }
-
-/**
- * semphr. h
- * <pre>xSemaphoreTake(
- * xSemaphoreHandle xSemaphore,
- * portTickType xBlockTime
- * )</pre>
- *
- * <i>Macro</i> to obtain a semaphore. The semaphore must have previously been
- * created with a call to vSemaphoreCreateBinary(), xSemaphoreCreateMutex() or
- * xSemaphoreCreateCounting().
- *
- * @param xSemaphore A handle to the semaphore being taken - obtained when
- * the semaphore was created.
- *
- * @param xBlockTime The time in ticks to wait for the semaphore to become
- * available. The macro portTICK_RATE_MS can be used to convert this to a
- * real time. A block time of zero can be used to poll the semaphore. A block
- * time of portMAX_DELAY can be used to block indefinitely (provided
- * INCLUDE_vTaskSuspend is set to 1 in FreeRTOSConfig.h).
- *
- * @return pdTRUE if the semaphore was obtained. pdFALSE
- * if xBlockTime expired without the semaphore becoming available.
- *
- * Example usage:
- <pre>
- xSemaphoreHandle xSemaphore = NULL;
-
- // A task that creates a semaphore.
- void vATask( void * pvParameters )
- {
- // Create the semaphore to guard a shared resource.
- vSemaphoreCreateBinary( xSemaphore );
- }
-
- // A task that uses the semaphore.
- void vAnotherTask( void * pvParameters )
- {
- // ... Do other things.
-
- if( xSemaphore != NULL )
- {
- // See if we can obtain the semaphore. If the semaphore is not available
- // wait 10 ticks to see if it becomes free.
- if( xSemaphoreTake( xSemaphore, ( portTickType ) 10 ) == pdTRUE )
- {
- // We were able to obtain the semaphore and can now access the
- // shared resource.
-
- // ...
-
- // We have finished accessing the shared resource. Release the
- // semaphore.
- xSemaphoreGive( xSemaphore );
- }
- else
- {
- // We could not obtain the semaphore and can therefore not access
- // the shared resource safely.
- }
- }
- }
- </pre>
- * \defgroup xSemaphoreTake xSemaphoreTake
- * \ingroup Semaphores
- */
-#define xSemaphoreTake( xSemaphore, xBlockTime ) xQueueGenericReceive( ( xQueueHandle ) xSemaphore, NULL, xBlockTime, pdFALSE )
-
-/**
- * semphr. h
- * xSemaphoreTakeRecursive(
- * xSemaphoreHandle xMutex,
- * portTickType xBlockTime
- * )
- *
- * <i>Macro</i> to recursively obtain, or 'take', a mutex type semaphore.
- * The mutex must have previously been created using a call to
- * xSemaphoreCreateRecursiveMutex();
- *
- * configUSE_RECURSIVE_MUTEXES must be set to 1 in FreeRTOSConfig.h for this
- * macro to be available.
- *
- * This macro must not be used on mutexes created using xSemaphoreCreateMutex().
- *
- * A mutex used recursively can be 'taken' repeatedly by the owner. The mutex
- * doesn't become available again until the owner has called
- * xSemaphoreGiveRecursive() for each successful 'take' request. For example,
- * if a task successfully 'takes' the same mutex 5 times then the mutex will
- * not be available to any other task until it has also 'given' the mutex back
- * exactly five times.
- *
- * @param xMutex A handle to the mutex being obtained. This is the
- * handle returned by xSemaphoreCreateRecursiveMutex();
- *
- * @param xBlockTime The time in ticks to wait for the semaphore to become
- * available. The macro portTICK_RATE_MS can be used to convert this to a
- * real time. A block time of zero can be used to poll the semaphore. If
- * the task already owns the semaphore then xSemaphoreTakeRecursive() will
- * return immediately no matter what the value of xBlockTime.
- *
- * @return pdTRUE if the semaphore was obtained. pdFALSE if xBlockTime
- * expired without the semaphore becoming available.
- *
- * Example usage:
- <pre>
- xSemaphoreHandle xMutex = NULL;
-
- // A task that creates a mutex.
- void vATask( void * pvParameters )
- {
- // Create the mutex to guard a shared resource.
- xMutex = xSemaphoreCreateRecursiveMutex();
- }
-
- // A task that uses the mutex.
- void vAnotherTask( void * pvParameters )
- {
- // ... Do other things.
-
- if( xMutex != NULL )
- {
- // See if we can obtain the mutex. If the mutex is not available
- // wait 10 ticks to see if it becomes free.
- if( xSemaphoreTakeRecursive( xSemaphore, ( portTickType ) 10 ) == pdTRUE )
- {
- // We were able to obtain the mutex and can now access the
- // shared resource.
-
- // ...
- // For some reason due to the nature of the code further calls to
- // xSemaphoreTakeRecursive() are made on the same mutex. In real
- // code these would not be just sequential calls as this would make
- // no sense. Instead the calls are likely to be buried inside
- // a more complex call structure.
- xSemaphoreTakeRecursive( xMutex, ( portTickType ) 10 );
- xSemaphoreTakeRecursive( xMutex, ( portTickType ) 10 );
-
- // The mutex has now been 'taken' three times, so will not be
- // available to another task until it has also been given back
- // three times. Again it is unlikely that real code would have
- // these calls sequentially, but instead buried in a more complex
- // call structure. This is just for illustrative purposes.
- xSemaphoreGiveRecursive( xMutex );
- xSemaphoreGiveRecursive( xMutex );
- xSemaphoreGiveRecursive( xMutex );
-
- // Now the mutex can be taken by other tasks.
- }
- else
- {
- // We could not obtain the mutex and can therefore not access
- // the shared resource safely.
- }
- }
- }
- </pre>
- * \defgroup xSemaphoreTakeRecursive xSemaphoreTakeRecursive
- * \ingroup Semaphores
- */
-#define xSemaphoreTakeRecursive( xMutex, xBlockTime ) xQueueTakeMutexRecursive( xMutex, xBlockTime )
-
-
-/*
- * xSemaphoreAltTake() is an alternative version of xSemaphoreTake().
- *
- * The source code that implements the alternative (Alt) API is much
- * simpler because it executes everything from within a critical section.
- * This is the approach taken by many other RTOSes, but FreeRTOS.org has the
- * preferred fully featured API too. The fully featured API has more
- * complex code that takes longer to execute, but makes much less use of
- * critical sections. Therefore the alternative API sacrifices interrupt
- * responsiveness to gain execution speed, whereas the fully featured API
- * sacrifices execution speed to ensure better interrupt responsiveness.
- */
-#define xSemaphoreAltTake( xSemaphore, xBlockTime ) xQueueAltGenericReceive( ( xQueueHandle ) xSemaphore, NULL, xBlockTime, pdFALSE )
-
-/**
- * semphr. h
- * <pre>xSemaphoreGive( xSemaphoreHandle xSemaphore )</pre>
- *
- * <i>Macro</i> to release a semaphore. The semaphore must have previously been
- * created with a call to vSemaphoreCreateBinary(), xSemaphoreCreateMutex() or
- * xSemaphoreCreateCounting(). and obtained using sSemaphoreTake().
- *
- * This macro must not be used from an ISR. See xSemaphoreGiveFromISR () for
- * an alternative which can be used from an ISR.
- *
- * This macro must also not be used on semaphores created using
- * xSemaphoreCreateRecursiveMutex().
- *
- * @param xSemaphore A handle to the semaphore being released. This is the
- * handle returned when the semaphore was created.
- *
- * @return pdTRUE if the semaphore was released. pdFALSE if an error occurred.
- * Semaphores are implemented using queues. An error can occur if there is
- * no space on the queue to post a message - indicating that the
- * semaphore was not first obtained correctly.
- *
- * Example usage:
- <pre>
- xSemaphoreHandle xSemaphore = NULL;
-
- void vATask( void * pvParameters )
- {
- // Create the semaphore to guard a shared resource.
- vSemaphoreCreateBinary( xSemaphore );
-
- if( xSemaphore != NULL )
- {
- if( xSemaphoreGive( xSemaphore ) != pdTRUE )
- {
- // We would expect this call to fail because we cannot give
- // a semaphore without first "taking" it!
- }
-
- // Obtain the semaphore - don't block if the semaphore is not
- // immediately available.
- if( xSemaphoreTake( xSemaphore, ( portTickType ) 0 ) )
- {
- // We now have the semaphore and can access the shared resource.
-
- // ...
-
- // We have finished accessing the shared resource so can free the
- // semaphore.
- if( xSemaphoreGive( xSemaphore ) != pdTRUE )
- {
- // We would not expect this call to fail because we must have
- // obtained the semaphore to get here.
- }
- }
- }
- }
- </pre>
- * \defgroup xSemaphoreGive xSemaphoreGive
- * \ingroup Semaphores
- */
-#define xSemaphoreGive( xSemaphore ) xQueueGenericSend( ( xQueueHandle ) xSemaphore, NULL, semGIVE_BLOCK_TIME, queueSEND_TO_BACK )
-
-/**
- * semphr. h
- * <pre>xSemaphoreGiveRecursive( xSemaphoreHandle xMutex )</pre>
- *
- * <i>Macro</i> to recursively release, or 'give', a mutex type semaphore.
- * The mutex must have previously been created using a call to
- * xSemaphoreCreateRecursiveMutex();
- *
- * configUSE_RECURSIVE_MUTEXES must be set to 1 in FreeRTOSConfig.h for this
- * macro to be available.
- *
- * This macro must not be used on mutexes created using xSemaphoreCreateMutex().
- *
- * A mutex used recursively can be 'taken' repeatedly by the owner. The mutex
- * doesn't become available again until the owner has called
- * xSemaphoreGiveRecursive() for each successful 'take' request. For example,
- * if a task successfully 'takes' the same mutex 5 times then the mutex will
- * not be available to any other task until it has also 'given' the mutex back
- * exactly five times.
- *
- * @param xMutex A handle to the mutex being released, or 'given'. This is the
- * handle returned by xSemaphoreCreateMutex();
- *
- * @return pdTRUE if the semaphore was given.
- *
- * Example usage:
- <pre>
- xSemaphoreHandle xMutex = NULL;
-
- // A task that creates a mutex.
- void vATask( void * pvParameters )
- {
- // Create the mutex to guard a shared resource.
- xMutex = xSemaphoreCreateRecursiveMutex();
- }
-
- // A task that uses the mutex.
- void vAnotherTask( void * pvParameters )
- {
- // ... Do other things.
-
- if( xMutex != NULL )
- {
- // See if we can obtain the mutex. If the mutex is not available
- // wait 10 ticks to see if it becomes free.
- if( xSemaphoreTakeRecursive( xMutex, ( portTickType ) 10 ) == pdTRUE )
- {
- // We were able to obtain the mutex and can now access the
- // shared resource.
-
- // ...
- // For some reason due to the nature of the code further calls to
- // xSemaphoreTakeRecursive() are made on the same mutex. In real
- // code these would not be just sequential calls as this would make
- // no sense. Instead the calls are likely to be buried inside
- // a more complex call structure.
- xSemaphoreTakeRecursive( xMutex, ( portTickType ) 10 );
- xSemaphoreTakeRecursive( xMutex, ( portTickType ) 10 );
-
- // The mutex has now been 'taken' three times, so will not be
- // available to another task until it has also been given back
- // three times. Again it is unlikely that real code would have
- // these calls sequentially, it would be more likely that the calls
- // to xSemaphoreGiveRecursive() would be called as a call stack
- // unwound. This is just for demonstrative purposes.
- xSemaphoreGiveRecursive( xMutex );
- xSemaphoreGiveRecursive( xMutex );
- xSemaphoreGiveRecursive( xMutex );
-
- // Now the mutex can be taken by other tasks.
- }
- else
- {
- // We could not obtain the mutex and can therefore not access
- // the shared resource safely.
- }
- }
- }
- </pre>
- * \defgroup xSemaphoreGiveRecursive xSemaphoreGiveRecursive
- * \ingroup Semaphores
- */
-#define xSemaphoreGiveRecursive( xMutex ) xQueueGiveMutexRecursive( xMutex )
-
-/*
- * xSemaphoreAltGive() is an alternative version of xSemaphoreGive().
- *
- * The source code that implements the alternative (Alt) API is much
- * simpler because it executes everything from within a critical section.
- * This is the approach taken by many other RTOSes, but FreeRTOS.org has the
- * preferred fully featured API too. The fully featured API has more
- * complex code that takes longer to execute, but makes much less use of
- * critical sections. Therefore the alternative API sacrifices interrupt
- * responsiveness to gain execution speed, whereas the fully featured API
- * sacrifices execution speed to ensure better interrupt responsiveness.
- */
-#define xSemaphoreAltGive( xSemaphore ) xQueueAltGenericSend( ( xQueueHandle ) xSemaphore, NULL, semGIVE_BLOCK_TIME, queueSEND_TO_BACK )
-
-/**
- * semphr. h
- * <pre>
- xSemaphoreGiveFromISR(
- xSemaphoreHandle xSemaphore,
- signed portBASE_TYPE *pxHigherPriorityTaskWoken
- )</pre>
- *
- * <i>Macro</i> to release a semaphore. The semaphore must have previously been
- * created with a call to vSemaphoreCreateBinary() or xSemaphoreCreateCounting().
- *
- * Mutex type semaphores (those created using a call to xSemaphoreCreateMutex())
- * must not be used with this macro.
- *
- * This macro can be used from an ISR.
- *
- * @param xSemaphore A handle to the semaphore being released. This is the
- * handle returned when the semaphore was created.
- *
- * @param pxHigherPriorityTaskWoken xSemaphoreGiveFromISR() will set
- * *pxHigherPriorityTaskWoken to pdTRUE if giving the semaphore caused a task
- * to unblock, and the unblocked task has a priority higher than the currently
- * running task. If xSemaphoreGiveFromISR() sets this value to pdTRUE then
- * a context switch should be requested before the interrupt is exited.
- *
- * @return pdTRUE if the semaphore was successfully given, otherwise errQUEUE_FULL.
- *
- * Example usage:
- <pre>
- \#define LONG_TIME 0xffff
- \#define TICKS_TO_WAIT 10
- xSemaphoreHandle xSemaphore = NULL;
-
- // Repetitive task.
- void vATask( void * pvParameters )
- {
- for( ;; )
- {
- // We want this task to run every 10 ticks of a timer. The semaphore
- // was created before this task was started.
-
- // Block waiting for the semaphore to become available.
- if( xSemaphoreTake( xSemaphore, LONG_TIME ) == pdTRUE )
- {
- // It is time to execute.
-
- // ...
-
- // We have finished our task. Return to the top of the loop where
- // we will block on the semaphore until it is time to execute
- // again. Note when using the semaphore for synchronisation with an
- // ISR in this manner there is no need to 'give' the semaphore back.
- }
- }
- }
-
- // Timer ISR
- void vTimerISR( void * pvParameters )
- {
- static unsigned char ucLocalTickCount = 0;
- static signed portBASE_TYPE xHigherPriorityTaskWoken;
-
- // A timer tick has occurred.
-
- // ... Do other time functions.
-
- // Is it time for vATask () to run?
- xHigherPriorityTaskWoken = pdFALSE;
- ucLocalTickCount++;
- if( ucLocalTickCount >= TICKS_TO_WAIT )
- {
- // Unblock the task by releasing the semaphore.
- xSemaphoreGiveFromISR( xSemaphore, &xHigherPriorityTaskWoken );
-
- // Reset the count so we release the semaphore again in 10 ticks time.
- ucLocalTickCount = 0;
- }
-
- if( xHigherPriorityTaskWoken != pdFALSE )
- {
- // We can force a context switch here. Context switching from an
- // ISR uses port specific syntax. Check the demo task for your port
- // to find the syntax required.
- }
- }
- </pre>
- * \defgroup xSemaphoreGiveFromISR xSemaphoreGiveFromISR
- * \ingroup Semaphores
- */
-#define xSemaphoreGiveFromISR( xSemaphore, pxHigherPriorityTaskWoken ) xQueueGenericSendFromISR( ( xQueueHandle ) xSemaphore, NULL, pxHigherPriorityTaskWoken, queueSEND_TO_BACK )
-
-/**
- * semphr. h
- * <pre>xSemaphoreHandle xSemaphoreCreateMutex( void )</pre>
- *
- * <i>Macro</i> that implements a mutex semaphore by using the existing queue
- * mechanism.
- *
- * Mutexes created using this macro can be accessed using the xSemaphoreTake()
- * and xSemaphoreGive() macros. The xSemaphoreTakeRecursive() and
- * xSemaphoreGiveRecursive() macros should not be used.
- *
- * This type of semaphore uses a priority inheritance mechanism so a task
- * 'taking' a semaphore MUST ALWAYS 'give' the semaphore back once the
- * semaphore it is no longer required.
- *
- * Mutex type semaphores cannot be used from within interrupt service routines.
- *
- * See vSemaphoreCreateBinary() for an alternative implementation that can be
- * used for pure synchronisation (where one task or interrupt always 'gives' the
- * semaphore and another always 'takes' the semaphore) and from within interrupt
- * service routines.
- *
- * @return xSemaphore Handle to the created mutex semaphore. Should be of type
- * xSemaphoreHandle.
- *
- * Example usage:
- <pre>
- xSemaphoreHandle xSemaphore;
-
- void vATask( void * pvParameters )
- {
- // Semaphore cannot be used before a call to xSemaphoreCreateMutex().
- // This is a macro so pass the variable in directly.
- xSemaphore = xSemaphoreCreateMutex();
-
- if( xSemaphore != NULL )
- {
- // The semaphore was created successfully.
- // The semaphore can now be used.
- }
- }
- </pre>
- * \defgroup vSemaphoreCreateMutex vSemaphoreCreateMutex
- * \ingroup Semaphores
- */
-#define xSemaphoreCreateMutex() xQueueCreateMutex()
-
-
-/**
- * semphr. h
- * <pre>xSemaphoreHandle xSemaphoreCreateRecursiveMutex( void )</pre>
- *
- * <i>Macro</i> that implements a recursive mutex by using the existing queue
- * mechanism.
- *
- * Mutexes created using this macro can be accessed using the
- * xSemaphoreTakeRecursive() and xSemaphoreGiveRecursive() macros. The
- * xSemaphoreTake() and xSemaphoreGive() macros should not be used.
- *
- * A mutex used recursively can be 'taken' repeatedly by the owner. The mutex
- * doesn't become available again until the owner has called
- * xSemaphoreGiveRecursive() for each successful 'take' request. For example,
- * if a task successfully 'takes' the same mutex 5 times then the mutex will
- * not be available to any other task until it has also 'given' the mutex back
- * exactly five times.
- *
- * This type of semaphore uses a priority inheritance mechanism so a task
- * 'taking' a semaphore MUST ALWAYS 'give' the semaphore back once the
- * semaphore it is no longer required.
- *
- * Mutex type semaphores cannot be used from within interrupt service routines.
- *
- * See vSemaphoreCreateBinary() for an alternative implementation that can be
- * used for pure synchronisation (where one task or interrupt always 'gives' the
- * semaphore and another always 'takes' the semaphore) and from within interrupt
- * service routines.
- *
- * @return xSemaphore Handle to the created mutex semaphore. Should be of type
- * xSemaphoreHandle.
- *
- * Example usage:
- <pre>
- xSemaphoreHandle xSemaphore;
-
- void vATask( void * pvParameters )
- {
- // Semaphore cannot be used before a call to xSemaphoreCreateMutex().
- // This is a macro so pass the variable in directly.
- xSemaphore = xSemaphoreCreateRecursiveMutex();
-
- if( xSemaphore != NULL )
- {
- // The semaphore was created successfully.
- // The semaphore can now be used.
- }
- }
- </pre>
- * \defgroup vSemaphoreCreateMutex vSemaphoreCreateMutex
- * \ingroup Semaphores
- */
-#define xSemaphoreCreateRecursiveMutex() xQueueCreateMutex()
-
-/**
- * semphr. h
- * <pre>xSemaphoreHandle xSemaphoreCreateCounting( unsigned portBASE_TYPE uxMaxCount, unsigned portBASE_TYPE uxInitialCount )</pre>
- *
- * <i>Macro</i> that creates a counting semaphore by using the existing
- * queue mechanism.
- *
- * Counting semaphores are typically used for two things:
- *
- * 1) Counting events.
- *
- * In this usage scenario an event handler will 'give' a semaphore each time
- * an event occurs (incrementing the semaphore count value), and a handler
- * task will 'take' a semaphore each time it processes an event
- * (decrementing the semaphore count value). The count value is therefore
- * the difference between the number of events that have occurred and the
- * number that have been processed. In this case it is desirable for the
- * initial count value to be zero.
- *
- * 2) Resource management.
- *
- * In this usage scenario the count value indicates the number of resources
- * available. To obtain control of a resource a task must first obtain a
- * semaphore - decrementing the semaphore count value. When the count value
- * reaches zero there are no free resources. When a task finishes with the
- * resource it 'gives' the semaphore back - incrementing the semaphore count
- * value. In this case it is desirable for the initial count value to be
- * equal to the maximum count value, indicating that all resources are free.
- *
- * @param uxMaxCount The maximum count value that can be reached. When the
- * semaphore reaches this value it can no longer be 'given'.
- *
- * @param uxInitialCount The count value assigned to the semaphore when it is
- * created.
- *
- * @return Handle to the created semaphore. Null if the semaphore could not be
- * created.
- *
- * Example usage:
- <pre>
- xSemaphoreHandle xSemaphore;
-
- void vATask( void * pvParameters )
- {
- xSemaphoreHandle xSemaphore = NULL;
-
- // Semaphore cannot be used before a call to xSemaphoreCreateCounting().
- // The max value to which the semaphore can count should be 10, and the
- // initial value assigned to the count should be 0.
- xSemaphore = xSemaphoreCreateCounting( 10, 0 );
-
- if( xSemaphore != NULL )
- {
- // The semaphore was created successfully.
- // The semaphore can now be used.
- }
- }
- </pre>
- * \defgroup xSemaphoreCreateCounting xSemaphoreCreateCounting
- * \ingroup Semaphores
- */
-#define xSemaphoreCreateCounting( uxMaxCount, uxInitialCount ) xQueueCreateCountingSemaphore( uxMaxCount, uxInitialCount )
-
-
-#endif /* SEMAPHORE_H */
-
-
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