xStreamBufferIsEmpty() function

{c} void vAFunction( StreamBufferHandle_t xStreamBuffer ) { size_t xBytesSent; uint8_t ucArrayToSend[] = { 0, 1, 2, 3 }; char *pcStringToSend = "String to send"; const TickType_t x100ms = pdMS_TO_TICKS( 100 ); // Send an array to the stream buffer, blocking for a maximum of 100ms to // wait for enough space to be available in the stream buffer. xBytesSent = xStreamBufferSend( xStreamBuffer, ( void * ) ucArrayToSend, sizeof( ucArrayToSend ), x100ms ); if( xBytesSent != sizeof( ucArrayToSend ) ) { // The call to xStreamBufferSend() times out before there was enough // space in the buffer for the data to be written, but it did // successfully write xBytesSent bytes. } // Send the string to the stream buffer. Return immediately if there is not // enough space in the buffer. xBytesSent = xStreamBufferSend( xStreamBuffer, ( void * ) pcStringToSend, strlen( pcStringToSend ), 0 ); if( xBytesSent != strlen( pcStringToSend ) ) { // The entire string could not be added to the stream buffer because // there was not enough free space in the buffer, but xBytesSent bytes // were sent. Could try again to send the remaining bytes. } }

{c} // A stream buffer that has already been created. StreamBufferHandle_t xStreamBuffer; void vAnInterruptServiceRoutine( void ) { size_t xBytesSent; char *pcStringToSend = "String to send"; BaseType_t xHigherPriorityTaskWoken = pdFALSE; // Initialised to pdFALSE. // Attempt to send the string to the stream buffer. xBytesSent = xStreamBufferSendFromISR( xStreamBuffer, ( void * ) pcStringToSend, strlen( pcStringToSend ), &xHigherPriorityTaskWoken ); if( xBytesSent != strlen( pcStringToSend ) ) { // There was not enough free space in the stream buffer for the entire // string to be written, ut xBytesSent bytes were written. } // If xHigherPriorityTaskWoken was set to pdTRUE inside // xStreamBufferSendFromISR() then a task that has a priority above the // priority of the currently executing task was unblocked and a context // switch should be performed to ensure the ISR returns to the unblocked // task. In most FreeRTOS ports this is done by simply passing // xHigherPriorityTaskWoken into portYIELD_FROM_ISR(), which will test the // variables value, and perform the context switch if necessary. Check the // documentation for the port in use for port specific instructions. portYIELD_FROM_ISR( xHigherPriorityTaskWoken ); }

{c} void vAFunction( StreamBuffer_t xStreamBuffer ) { uint8_t ucRxData[ 20 ]; size_t xReceivedBytes; const TickType_t xBlockTime = pdMS_TO_TICKS( 20 ); // Receive up to another sizeof( ucRxData ) bytes from the stream buffer. // Wait in the Blocked state (so not using any CPU processing time) for a // maximum of 100ms for the full sizeof( ucRxData ) number of bytes to be // available. xReceivedBytes = xStreamBufferReceive( xStreamBuffer, ( void * ) ucRxData, sizeof( ucRxData ), xBlockTime ); if( xReceivedBytes > 0 ) { // A ucRxData contains another xReceivedBytes bytes of data, which can // be processed here.... } }

{c} // A stream buffer that has already been created. StreamBuffer_t xStreamBuffer; void vAnInterruptServiceRoutine( void ) { uint8_t ucRxData[ 20 ]; size_t xReceivedBytes; BaseType_t xHigherPriorityTaskWoken = pdFALSE; // Initialised to pdFALSE. // Receive the next stream from the stream buffer. xReceivedBytes = xStreamBufferReceiveFromISR( xStreamBuffer, ( void * ) ucRxData, sizeof( ucRxData ), &xHigherPriorityTaskWoken ); if( xReceivedBytes > 0 ) { // ucRxData contains xReceivedBytes read from the stream buffer. // Process the stream here.... } // If xHigherPriorityTaskWoken was set to pdTRUE inside // xStreamBufferReceiveFromISR() then a task that has a priority above the // priority of the currently executing task was unblocked and a context // switch should be performed to ensure the ISR returns to the unblocked // task. In most FreeRTOS ports this is done by simply passing // xHigherPriorityTaskWoken into portYIELD_FROM_ISR(), which will test the // variables value, and perform the context switch if necessary. Check the // documentation for the port in use for port specific instructions. portYIELD_FROM_ISR( xHigherPriorityTaskWoken ); }