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Minor updates to comment block for xTaskCheckForTimeOut().
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Richard Barry
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commit
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@ -2201,6 +2201,103 @@ uint32_t ulTaskNotifyTake( BaseType_t xClearCountOnExit, TickType_t xTicksToWait
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*/
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BaseType_t xTaskNotifyStateClear( TaskHandle_t xTask );
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/**
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* task.h
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* <pre>void vTaskSetTimeOutState( TimeOut_t * const pxTimeOut )</pre>
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*
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* Capture the current time for future use with xTaskCheckForTimeOut().
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*
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* @param pxTimeOut Pointer to a timeout object into which the current time
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* is to be captured. The captured time includes the tick count and the number
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* of times the tick count has overflowed since the system first booted.
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* \defgroup vTaskSetTimeOutState vTaskSetTimeOutState
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* \ingroup TaskCtrl
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*/
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void vTaskSetTimeOutState( TimeOut_t * const pxTimeOut ) PRIVILEGED_FUNCTION;
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/**
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* task.h
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* <pre>BaseType_t xTaskCheckForTimeOut( TimeOut_t * const pxTimeOut, TickType_t * const pxTicksToWait );</pre>
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*
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* Determines if pxTicksToWait ticks has passed since a time was captured
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* using a call to vTaskSetTimeOutState(). The captured time includes the tick
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* count and the number of times the tick count has overflowed.
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*
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* @param pxTimeOut The time status as captured previously using
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* vTaskSetTimeOutState. If the timeout has not yet occurred, it is updated
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* to reflect the current time status.
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* @param pxTicksToWait The number of ticks to check for timeout i.e. if
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* pxTicksToWait ticks have passed since pxTimeOut was last updated (either by
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* vTaskSetTimeOutState() or xTaskCheckForTimeOut()), the timeout has occurred.
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* If the timeout has not occurred, pxTIcksToWait is updated to reflect the
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* number of remaining ticks.
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*
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* @return If timeout has occurred, pdTRUE is returned. Otherwise pdFALSE is
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* returned and pxTicksToWait is updated to reflect the number of remaining
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* ticks.
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*
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* @see https://www.freertos.org/xTaskCheckForTimeOut.html
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*
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* Example Usage:
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* <pre>
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// Driver library function used to receive uxWantedBytes from an Rx buffer
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// that is filled by a UART interrupt. If there are not enough bytes in the
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// Rx buffer then the task enters the Blocked state until it is notified that
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// more data has been placed into the buffer. If there is still not enough
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// data then the task re-enters the Blocked state, and xTaskCheckForTimeOut()
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// is used to re-calculate the Block time to ensure the total amount of time
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// spent in the Blocked state does not exceed MAX_TIME_TO_WAIT. This
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// continues until either the buffer contains at least uxWantedBytes bytes,
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// or the total amount of time spent in the Blocked state reaches
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// MAX_TIME_TO_WAIT – at which point the task reads however many bytes are
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// available up to a maximum of uxWantedBytes.
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size_t xUART_Receive( uint8_t *pucBuffer, size_t uxWantedBytes )
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{
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size_t uxReceived = 0;
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TickType_t xTicksToWait = MAX_TIME_TO_WAIT;
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TimeOut_t xTimeOut;
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// Initialize xTimeOut. This records the time at which this function
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// was entered.
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vTaskSetTimeOutState( &xTimeOut );
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// Loop until the buffer contains the wanted number of bytes, or a
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// timeout occurs.
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while( UART_bytes_in_rx_buffer( pxUARTInstance ) < uxWantedBytes )
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{
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// The buffer didn't contain enough data so this task is going to
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// enter the Blocked state. Adjusting xTicksToWait to account for
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// any time that has been spent in the Blocked state within this
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// function so far to ensure the total amount of time spent in the
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// Blocked state does not exceed MAX_TIME_TO_WAIT.
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if( xTaskCheckForTimeOut( &xTimeOut, &xTicksToWait ) != pdFALSE )
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{
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//Timed out before the wanted number of bytes were available,
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// exit the loop.
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break;
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}
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// Wait for a maximum of xTicksToWait ticks to be notified that the
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// receive interrupt has placed more data into the buffer.
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ulTaskNotifyTake( pdTRUE, xTicksToWait );
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}
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// Attempt to read uxWantedBytes from the receive buffer into pucBuffer.
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// The actual number of bytes read (which might be less than
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// uxWantedBytes) is returned.
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uxReceived = UART_read_from_receive_buffer( pxUARTInstance,
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pucBuffer,
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uxWantedBytes );
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return uxReceived;
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}
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</pre>
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* \defgroup xTaskCheckForTimeOut xTaskCheckForTimeOut
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* \ingroup TaskCtrl
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*/
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BaseType_t xTaskCheckForTimeOut( TimeOut_t * const pxTimeOut, TickType_t * const pxTicksToWait ) PRIVILEGED_FUNCTION;
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/*-----------------------------------------------------------
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* SCHEDULER INTERNALS AVAILABLE FOR PORTING PURPOSES
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*----------------------------------------------------------*/
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@ -2317,90 +2414,6 @@ TickType_t uxTaskResetEventItemValue( void ) PRIVILEGED_FUNCTION;
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*/
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TaskHandle_t xTaskGetCurrentTaskHandle( void ) PRIVILEGED_FUNCTION;
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/*
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* Capture the current time status for future reference.
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*
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* @param[out] pxTimeOut Pointer to a timeout object into which the current
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* time status is to be captured.
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*/
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void vTaskSetTimeOutState( TimeOut_t * const pxTimeOut ) PRIVILEGED_FUNCTION;
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/*
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* Compare the time status now with the one previously captured using
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* vTaskSetTimeOutState to check if the timeout has occurred.
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*
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* @param[in/out] pxTimeOut The time status as captured previously using
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* vTaskSetTimeOutState. If the timeout has not yet occurred, it is updated
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* to reflect the current time status.
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* @param[in/out] pxTicksToWait The number of ticks to check for timeout i.e. if
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* pxTicksToWait ticks have passed since pxTimeOut was last updated (either by
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* vTaskSetTimeOutState or xTaskCheckForTimeOut), the timeout has occurred. If
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* the timeout has not occurred, it is updated to reflect the number of
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* reamaining ticks.
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*
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* @return If timeout has occurred, pdTRUE is returned. Otherwise pdFALSE is
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* returned and pxTicksToWait is updated to reflect the number of remaining
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* ticks.
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*
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* @see https://www.freertos.org/xTaskCheckForTimeOut.html
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*
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* Example Usage:
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*
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* // Driver library function used to receive uxWantedBytes from an Rx buffer
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* // that is filled by a UART interrupt. If there are not enough bytes in the
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* // Rx buffer then the task enters the Blocked state until it is notified that
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* // more data has been placed into the buffer. If there is still not enough
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* // data then the task re-enters the Blocked state, and xTaskCheckForTimeOut()
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* // is used to re-calculate the Block time to ensure the total amount of time
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* // spent in the Blocked state does not exceed MAX_TIME_TO_WAIT. This
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* // continues until either the buffer contains at least uxWantedBytes bytes,
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* // or the total amount of time spent in the Blocked state reaches
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* // MAX_TIME_TO_WAIT – at which point the task reads however many bytes are
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* // available up to a maximum of uxWantedBytes.
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*
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* size_t xUART_Receive( uint8_t *pucBuffer, size_t uxWantedBytes )
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* {
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* size_t uxReceived = 0;
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* TickType_t xTicksToWait = MAX_TIME_TO_WAIT;
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* TimeOut_t xTimeOut;
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*
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* // Initialize xTimeOut. This records the time at which this function
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* // was entered.
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* vTaskSetTimeOutState( &xTimeOut );
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*
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* // Loop until the buffer contains the wanted number of bytes, or a
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* // timeout occurs.
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* while( UART_bytes_in_rx_buffer( pxUARTInstance ) < uxWantedBytes )
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* {
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* // The buffer didn't contain enough data so this task is going to
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* // enter the Blocked state. Adjusting xTicksToWait to account for
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* // any time that has been spent in the Blocked state within this
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* // function so far to ensure the total amount of time spent in the
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* // Blocked state does not exceed MAX_TIME_TO_WAIT.
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* if( xTaskCheckForTimeOut( &xTimeOut, &xTicksToWait ) != pdFALSE )
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* {
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* //Timed out before the wanted number of bytes were available,
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* // exit the loop.
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* break;
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* }
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*
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* // Wait for a maximum of xTicksToWait ticks to be notified that the
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* // receive interrupt has placed more data into the buffer.
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* ulTaskNotifyTake( pdTRUE, xTicksToWait );
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* }
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*
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* // Attempt to read uxWantedBytes from the receive buffer into pucBuffer.
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* // The actual number of bytes read (which might be less than
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* // uxWantedBytes) is returned.
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* uxReceived = UART_read_from_receive_buffer( pxUARTInstance,
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* pucBuffer,
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* uxWantedBytes );
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*
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* return uxReceived;
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* }
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*/
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BaseType_t xTaskCheckForTimeOut( TimeOut_t * const pxTimeOut, TickType_t * const pxTicksToWait ) PRIVILEGED_FUNCTION;
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/*
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* Shortcut used by the queue implementation to prevent unnecessary call to
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* taskYIELD();
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