David Fletcher
Update revision to use TI's mqtt and Freertos.
Dependencies: mbed client server
Fork of
cc3100_Test_mqtt_CM3
by 
David Fletcher
Diff: FreeRTOS_V8_2_1/source/include/semphr.h
- Revision:
- 3:a8c249046181
--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/FreeRTOS_V8_2_1/source/include/semphr.h Thu Sep 03 14:02:37 2015 +0000
@@ -0,0 +1,845 @@
+/*
+ FreeRTOS V8.2.1 - Copyright (C) 2015 Real Time Engineers Ltd.
+ All rights reserved
+
+ VISIT http://www.FreeRTOS.org TO ENSURE YOU ARE USING THE LATEST VERSION.
+
+ 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 on the following
+ link: http://www.freertos.org/a00114.html
+
+ ***************************************************************************
+ * *
+ * FreeRTOS provides completely free yet professionally developed, *
+ * robust, strictly quality controlled, supported, and cross *
+ * platform software that is more than just the market leader, it *
+ * is the industry's de facto standard. *
+ * *
+ * Help yourself get started quickly while simultaneously helping *
+ * to support the FreeRTOS project by purchasing a FreeRTOS *
+ * tutorial book, reference manual, or both: *
+ * http://www.FreeRTOS.org/Documentation *
+ * *
+ ***************************************************************************
+
+ http://www.FreeRTOS.org/FAQHelp.html - Having a problem? Start by reading
+ the FAQ page "My application does not run, what could be wrong?". Have you
+ defined configASSERT()?
+
+ http://www.FreeRTOS.org/support - In return for receiving this top quality
+ embedded software for free we request you assist our global community by
+ participating in the support forum.
+
+ http://www.FreeRTOS.org/training - Investing in training allows your team to
+ be as productive as possible as early as possible. Now you can receive
+ FreeRTOS training directly from Richard Barry, CEO of Real Time Engineers
+ Ltd, and the world's leading authority on the world's leading RTOS.
+
+ 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.FreeRTOS.org/labs - Where new FreeRTOS products go to incubate.
+ Come and try FreeRTOS+TCP, our new open source TCP/IP stack for FreeRTOS.
+
+ http://www.OpenRTOS.com - Real Time Engineers ltd. license FreeRTOS to High
+ Integrity Systems ltd. to sell under the OpenRTOS brand. Low cost OpenRTOS
+ licenses offer ticketed support, indemnification and commercial 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 SEMAPHORE_H
+#define SEMAPHORE_H
+
+#ifndef INC_FREERTOS_H
+ #error "include FreeRTOS.h" must appear in source files before "include semphr.h"
+#endif
+
+#include "queue.h"
+
+typedef QueueHandle_t SemaphoreHandle_t;
+
+#define semBINARY_SEMAPHORE_QUEUE_LENGTH ( ( uint8_t ) 1U )
+#define semSEMAPHORE_QUEUE_ITEM_LENGTH ( ( uint8_t ) 0U )
+#define semGIVE_BLOCK_TIME ( ( TickType_t ) 0U )
+
+
+/**
+ * semphr. h
+ * <pre>vSemaphoreCreateBinary( SemaphoreHandle_t xSemaphore )</pre>
+ *
+ * This old vSemaphoreCreateBinary() macro is now deprecated in favour of the
+ * xSemaphoreCreateBinary() function. Note that binary semaphores created using
+ * the vSemaphoreCreateBinary() macro are created in a state such that the
+ * first call to 'take' the semaphore would pass, whereas binary semaphores
+ * created using xSemaphoreCreateBinary() are created in a state such that the
+ * the semaphore must first be 'given' before it can be 'taken'.
+ *
+ * <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 SemaphoreHandle_t.
+ *
+ * Example usage:
+ <pre>
+ SemaphoreHandle_t xSemaphore = NULL;
+
+ 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 ) = xQueueGenericCreate( ( UBaseType_t ) 1, semSEMAPHORE_QUEUE_ITEM_LENGTH, queueQUEUE_TYPE_BINARY_SEMAPHORE ); \
+ if( ( xSemaphore ) != NULL ) \
+ { \
+ ( void ) xSemaphoreGive( ( xSemaphore ) ); \
+ } \
+ }
+
+/**
+ * semphr. h
+ * <pre>SemaphoreHandle_t xSemaphoreCreateBinary( void )</pre>
+ *
+ * The old vSemaphoreCreateBinary() macro is now deprecated in favour of this
+ * xSemaphoreCreateBinary() function. Note that binary semaphores created using
+ * the vSemaphoreCreateBinary() macro are created in a state such that the
+ * first call to 'take' the semaphore would pass, whereas binary semaphores
+ * created using xSemaphoreCreateBinary() are created in a state such that the
+ * the semaphore must first be 'given' before it can be 'taken'.
+ *
+ * Function that creates 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 nothing is actually stored - all that is important is whether the queue is
+ * empty or full (the binary semaphore is available or not).
+ *
+ * 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().
+ *
+ * @return Handle to the created semaphore.
+ *
+ * Example usage:
+ <pre>
+ SemaphoreHandle_t xSemaphore = NULL;
+
+ void vATask( void * pvParameters )
+ {
+ // Semaphore cannot be used before a call to vSemaphoreCreateBinary ().
+ // This is a macro so pass the variable in directly.
+ xSemaphore = xSemaphoreCreateBinary();
+
+ if( xSemaphore != NULL )
+ {
+ // The semaphore was created successfully.
+ // The semaphore can now be used.
+ }
+ }
+ </pre>
+ * \defgroup vSemaphoreCreateBinary vSemaphoreCreateBinary
+ * \ingroup Semaphores
+ */
+#define xSemaphoreCreateBinary() xQueueGenericCreate( ( UBaseType_t ) 1, semSEMAPHORE_QUEUE_ITEM_LENGTH, queueQUEUE_TYPE_BINARY_SEMAPHORE )
+
+/**
+ * semphr. h
+ * <pre>xSemaphoreTake(
+ * SemaphoreHandle_t xSemaphore,
+ * TickType_t 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_PERIOD_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>
+ SemaphoreHandle_t 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, ( TickType_t ) 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( ( QueueHandle_t ) ( xSemaphore ), NULL, ( xBlockTime ), pdFALSE )
+
+/**
+ * semphr. h
+ * xSemaphoreTakeRecursive(
+ * SemaphoreHandle_t xMutex,
+ * TickType_t 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_PERIOD_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>
+ SemaphoreHandle_t 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, ( TickType_t ) 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, ( TickType_t ) 10 );
+ xSemaphoreTakeRecursive( xMutex, ( TickType_t ) 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( ( QueueHandle_t ) ( xSemaphore ), NULL, ( xBlockTime ), pdFALSE )
+
+/**
+ * semphr. h
+ * <pre>xSemaphoreGive( SemaphoreHandle_t 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>
+ SemaphoreHandle_t 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, ( TickType_t ) 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( ( QueueHandle_t ) ( xSemaphore ), NULL, semGIVE_BLOCK_TIME, queueSEND_TO_BACK )
+
+/**
+ * semphr. h
+ * <pre>xSemaphoreGiveRecursive( SemaphoreHandle_t 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>
+ SemaphoreHandle_t 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, ( TickType_t ) 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, ( TickType_t ) 10 );
+ xSemaphoreTakeRecursive( xMutex, ( TickType_t ) 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( ( QueueHandle_t ) ( xSemaphore ), NULL, semGIVE_BLOCK_TIME, queueSEND_TO_BACK )
+
+/**
+ * semphr. h
+ * <pre>
+ xSemaphoreGiveFromISR(
+ SemaphoreHandle_t xSemaphore,
+ BaseType_t *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
+ SemaphoreHandle_t 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 uint8_t ucLocalTickCount = 0;
+ static BaseType_t 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 ) xQueueGiveFromISR( ( QueueHandle_t ) ( xSemaphore ), ( pxHigherPriorityTaskWoken ) )
+
+/**
+ * semphr. h
+ * <pre>
+ xSemaphoreTakeFromISR(
+ SemaphoreHandle_t xSemaphore,
+ BaseType_t *pxHigherPriorityTaskWoken
+ )</pre>
+ *
+ * <i>Macro</i> to take a semaphore from an ISR. 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, however taking a semaphore from an ISR
+ * is not a common operation. It is likely to only be useful when taking a
+ * counting semaphore when an interrupt is obtaining an object from a resource
+ * pool (when the semaphore count indicates the number of resources available).
+ *
+ * @param xSemaphore A handle to the semaphore being taken. This is the
+ * handle returned when the semaphore was created.
+ *
+ * @param pxHigherPriorityTaskWoken xSemaphoreTakeFromISR() will set
+ * *pxHigherPriorityTaskWoken to pdTRUE if taking the semaphore caused a task
+ * to unblock, and the unblocked task has a priority higher than the currently
+ * running task. If xSemaphoreTakeFromISR() sets this value to pdTRUE then
+ * a context switch should be requested before the interrupt is exited.
+ *
+ * @return pdTRUE if the semaphore was successfully taken, otherwise
+ * pdFALSE
+ */
+#define xSemaphoreTakeFromISR( xSemaphore, pxHigherPriorityTaskWoken ) xQueueReceiveFromISR( ( QueueHandle_t ) ( xSemaphore ), NULL, ( pxHigherPriorityTaskWoken ) )
+
+/**
+ * semphr. h
+ * <pre>SemaphoreHandle_t 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
+ * SemaphoreHandle_t.
+ *
+ * Example usage:
+ <pre>
+ SemaphoreHandle_t 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( queueQUEUE_TYPE_MUTEX )
+
+
+/**
+ * semphr. h
+ * <pre>SemaphoreHandle_t 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
+ * SemaphoreHandle_t.
+ *
+ * Example usage:
+ <pre>
+ SemaphoreHandle_t 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( queueQUEUE_TYPE_RECURSIVE_MUTEX )
+
+/**
+ * semphr. h
+ * <pre>SemaphoreHandle_t xSemaphoreCreateCounting( UBaseType_t uxMaxCount, UBaseType_t 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>
+ SemaphoreHandle_t xSemaphore;
+
+ void vATask( void * pvParameters )
+ {
+ SemaphoreHandle_t 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 ) )
+
+/**
+ * semphr. h
+ * <pre>void vSemaphoreDelete( SemaphoreHandle_t xSemaphore );</pre>
+ *
+ * Delete a semaphore. This function must be used with care. For example,
+ * do not delete a mutex type semaphore if the mutex is held by a task.
+ *
+ * @param xSemaphore A handle to the semaphore to be deleted.
+ *
+ * \defgroup vSemaphoreDelete vSemaphoreDelete
+ * \ingroup Semaphores
+ */
+#define vSemaphoreDelete( xSemaphore ) vQueueDelete( ( QueueHandle_t ) ( xSemaphore ) )
+
+/**
+ * semphr.h
+ * <pre>TaskHandle_t xSemaphoreGetMutexHolder( SemaphoreHandle_t xMutex );</pre>
+ *
+ * If xMutex is indeed a mutex type semaphore, return the current mutex holder.
+ * If xMutex is not a mutex type semaphore, or the mutex is available (not held
+ * by a task), return NULL.
+ *
+ * Note: This is a good way of determining if the calling task is the mutex
+ * holder, but not a good way of determining the identity of the mutex holder as
+ * the holder may change between the function exiting and the returned value
+ * being tested.
+ */
+#define xSemaphoreGetMutexHolder( xSemaphore ) xQueueGetMutexHolder( ( xSemaphore ) )
+
+#endif /* SEMAPHORE_H */
+
+
+