xSemaphoreGiveRecursive macro

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. } } }