text: /*
      FreeRTOS V9.0.0 - Copyright (C) 2016 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,    *
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       *    platform software that is more than just the market leader, it     *
       *    is the industry's de facto standard.                               *
       *                                                                       *
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      ***************************************************************************
  
      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
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      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
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      licenses offer ticketed support, indemnification and commercial middleware.
  
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      1 tab == 4 spaces!
  */
  
  
  /* 
  	BASIC INTERRUPT DRIVEN SERIAL PORT DRIVER FOR UART
  */
  
  /* Scheduler includes. */
  #include "FreeRTOS.h"
  #include "queue.h"
  #include "task.h"
  
  /* Demo application includes. */
  #include "serial.h"
  
  /* Library includes. */
  #include "xparameters.h"
  #include "xuartlite.h"
  #include "xuartlite_l.h"
  
  /*-----------------------------------------------------------*/
  
  /* Queues used to hold received characters, and characters waiting to be
  transmitted. */
  static QueueHandle_t xRxedChars; 
  static QueueHandle_t xCharsForTx; 
  
  /* Structure that maintains information on the UART being used. */
  static XUartLite xUART;
  
  /*
   * Sample UART interrupt handler.  Note this is used to demonstrate the kernel
   * features and test the port - it is not intended to represent an efficient
   * implementation.
   */
  static void vSerialISR( XUartLite *pxUART );
  
  /*-----------------------------------------------------------*/
  
  xComPortHandle xSerialPortInitMinimal( unsigned long ulWantedBaud, unsigned portBASE_TYPE uxQueueLength )
  {
  	/* NOTE: The baud rate used by this driver is determined by the hardware
  	parameterization of the UART Lite peripheral, and the baud value passed to
  	this function has no effect. */
  	( void ) ulWantedBaud;
  
  	/* Create the queues used to hold Rx and Tx characters. */
  	xRxedChars = xQueueCreate( uxQueueLength, ( unsigned portBASE_TYPE ) sizeof( signed char ) );
  	xCharsForTx = xQueueCreate( uxQueueLength + 1, ( unsigned portBASE_TYPE ) sizeof( signed char ) );
  
  	/* Only initialise the UART if the queues were created correctly. */
  	if( ( xRxedChars != NULL ) && ( xCharsForTx != NULL ) )
  	{
  
  		XUartLite_Initialize( &xUART, XPAR_RS232_UART_1_DEVICE_ID );
  		XUartLite_ResetFifos( &xUART );
  		XUartLite_DisableInterrupt( &xUART );
  
  		if( xPortInstallInterruptHandler( XPAR_XPS_INTC_0_RS232_UART_1_INTERRUPT_INTR, ( XInterruptHandler )vSerialISR, (void *)&xUART ) == pdPASS )
  		{
  			/* xPortInstallInterruptHandler() could fail if 
  			vPortSetupInterruptController() has not been called prior to this 
  			function. */
  			XUartLite_EnableInterrupt( &xUART );
  		}
  	}
  	
  	/* There is only one port so the handle is not used. */
  	return ( xComPortHandle ) 0;
  }
  /*-----------------------------------------------------------*/
  
  signed portBASE_TYPE xSerialGetChar( xComPortHandle pxPort, signed char *pcRxedChar, TickType_t xBlockTime )
  {
  	/* The port handle is not required as this driver only supports one UART. */
  	( void ) pxPort;
  
  	/* Get the next character from the buffer.  Return false if no characters
  	are available, or arrive before xBlockTime expires. */
  	if( xQueueReceive( xRxedChars, pcRxedChar, xBlockTime ) )
  	{
  		return pdTRUE;
  	}
  	else
  	{
  		return pdFALSE;
  	}
  }
  /*-----------------------------------------------------------*/
  
  signed portBASE_TYPE xSerialPutChar( xComPortHandle pxPort, signed char cOutChar, TickType_t xBlockTime )
  {
  portBASE_TYPE xReturn = pdTRUE;
  
  	/* Just to remove compiler warning. */
  	( void ) pxPort;
  
  	portENTER_CRITICAL();
  	{
  		/* If the UART FIFO is full we can block posting the new data on the
  		Tx queue. */
  		if( XUartLite_mIsTransmitFull( XPAR_RS232_UART_1_BASEADDR ) )
  		{
  			if( xQueueSend( xCharsForTx, &cOutChar, xBlockTime ) != pdPASS )
  			{
  				xReturn = pdFAIL;
  			}
  		}
  		/* Otherwise, if there is data already in the queue we should add the
  		new data to the back of the queue to ensure the sequencing is 
  		maintained. */
  		else if( uxQueueMessagesWaiting( xCharsForTx ) )
  		{
  			if( xQueueSend( xCharsForTx, &cOutChar, xBlockTime ) != pdPASS )
  			{
  				xReturn = pdFAIL;
  			}			
  		}
  		/* If the UART FIFO is not full and there is no data already in the
  		queue we can write directly to the FIFO without disrupting the 
  		sequence. */
  		else
  		{
  			XIo_Out32( XPAR_RS232_UART_1_BASEADDR + XUL_TX_FIFO_OFFSET, cOutChar );
  		}
  	}
  	portEXIT_CRITICAL();
  
  	return xReturn;
  }
  /*-----------------------------------------------------------*/
  
  void vSerialClose( xComPortHandle xPort )
  {
  	/* Not supported as not required by the demo application. */
  	( void ) xPort;
  }
  /*-----------------------------------------------------------*/
  
  static void vSerialISR( XUartLite *pxUART )
  {
  unsigned long ulISRStatus;
  portBASE_TYPE xHigherPriorityTaskWoken = pdFALSE, lDidSomething;
  char cChar;
  
  	/* Just to remove compiler warning. */
  	( void ) pxUART;
  
  	do
  	{
  		lDidSomething = pdFALSE;
  
  		ulISRStatus = XIo_In32( XPAR_RS232_UART_1_BASEADDR + XUL_STATUS_REG_OFFSET );
  
  		if( ( ulISRStatus & XUL_SR_RX_FIFO_VALID_DATA ) != 0 )
  		{
  			/* A character is available - place it in the queue of received
  			characters.  This might wake a task that was blocked waiting for 
  			data. */
  			cChar = ( char ) XIo_In32( XPAR_RS232_UART_1_BASEADDR + XUL_RX_FIFO_OFFSET );
  			xQueueSendFromISR( xRxedChars, &cChar, &xHigherPriorityTaskWoken );
  			lDidSomething = pdTRUE;
  		}
  		
  		if( ( ulISRStatus & XUL_SR_TX_FIFO_EMPTY ) != 0 )
  		{
  			/* There is space in the FIFO - if there are any characters queue for
  			transmission they can be sent to the UART now.  This might unblock a
  			task that was waiting for space to become available on the Tx queue. */
  			if( xQueueReceiveFromISR( xCharsForTx, &cChar, &xHigherPriorityTaskWoken ) == pdTRUE )
  			{
  				XIo_Out32( XPAR_RS232_UART_1_BASEADDR + XUL_TX_FIFO_OFFSET, cChar );
  				lDidSomething = pdTRUE;
  			}			
  		}
  	} while( lDidSomething == pdTRUE );
  
  	/* If we woke any tasks we may require a context switch. */
  	if( xHigherPriorityTaskWoken )
  	{
  		portYIELD_FROM_ISR();
  	}
  }
  
  
  
  