text: /*
      FreeRTOS V9.0.0rc2 - 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,    *
       *    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!
  */
  
  
  /* BASIC INTERRUPT DRIVEN SERIAL PORT DRIVER.
   *
   * This is not a proper UART driver.  It only supports one port, uses loopback
   * mode, and is used to test interrupts that use the FreeRTOS API as part of
   * a wider test suite.  Nor is it intended to show an efficient implementation
   * of a UART interrupt service routine as queues are used to pass individual
   * characters one at a time!
   */
  
  /* Standard includes. */
  #include <stdlib.h>
  
  /* Scheduler includes. */
  #include "FreeRTOS.h"
  #include "queue.h"
  #include "task.h"
  
  /* Demo application includes. */
  #include "serial.h"
  
  /* Misc. constants. */
  #define serNO_BLOCK				( ( TickType_t ) 0 )
  
  /* The queue used to hold received characters. */
  static QueueHandle_t xRxedChars;
  
  /* The queue used to hold characters waiting transmission. */
  static QueueHandle_t xCharsForTx;
  
  /*-----------------------------------------------------------*/
  
  xComPortHandle xSerialPortInitMinimal( unsigned long ulWantedBaud, unsigned portBASE_TYPE uxQueueLength )
  {
  unsigned long ulBaudRateCount;
  
  	/* Initialise the hardware. */
  
  	/* Generate the baud rate constants for the wanted baud rate. */
  	ulBaudRateCount = configCPU_CLOCK_HZ / ulWantedBaud;
  
  	portENTER_CRITICAL();
  	{
  		/* Create the queues used by the com test task. */
  		xRxedChars = xQueueCreate( uxQueueLength, ( unsigned portBASE_TYPE ) sizeof( signed char ) );
  		xCharsForTx = xQueueCreate( uxQueueLength, ( unsigned portBASE_TYPE ) sizeof( signed char ) );
  
  		/* Reset UART. */
  		UCA1CTL1 |= UCSWRST;
  
  		/* Use SMCLK. */
  		UCA1CTL1 = UCSSEL0 | UCSSEL1;
  		
  		/* Setup baud rate low byte. */
  		UCA1BR0 = ( unsigned char ) ( ulBaudRateCount & ( unsigned long ) 0xff );
  
  		/* Setup baud rate high byte. */
  		ulBaudRateCount >>= 8UL;
  		UCA1BR1 = ( unsigned char ) ( ulBaudRateCount & ( unsigned long ) 0xff );
  
  		/* UCLISTEN sets loopback mode! */
  		UCA1STAT = UCLISTEN;
  
  		/* Enable interrupts. */
  		UCA1IE |= UCRXIE;
  		
  		/* Take out of reset. */
  		UCA1CTL1 &= ~UCSWRST;
  	}
  	portEXIT_CRITICAL();
  	
  	/* Note the comments at the top of this file about this not being a generic
  	UART driver. */
  	return NULL;
  }
  /*-----------------------------------------------------------*/
  
  signed portBASE_TYPE xSerialGetChar( xComPortHandle pxPort, signed char *pcRxedChar, TickType_t xBlockTime )
  {
  	/* 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 )
  {
  signed portBASE_TYPE xReturn;
  
  	/* Send the next character to the queue of characters waiting transmission,
  	then enable the UART Tx interrupt, just in case UART transmission has already
  	completed and switched itself off. */
  	xReturn = xQueueSend( xCharsForTx, &cOutChar, xBlockTime );
  	UCA1IE |= UCTXIE;
  
  	return xReturn;
  }
  /*-----------------------------------------------------------*/
  
  /* The implementation of this interrupt is provided to demonstrate the use
  of queues from inside an interrupt service routine.  It is *not* intended to
  be an efficient interrupt implementation.  A real application should make use
  of the DMA.  Or, as a minimum, transmission and reception could use a simple
  RAM ring buffer, and synchronise with a task using a semaphore when a complete
  message has been received or transmitted. */
  #pragma vector=USCI_A1_VECTOR
  static __interrupt void prvUSCI_A1_ISR( void )
  {
  signed char cChar;
  portBASE_TYPE xHigherPriorityTaskWoken = pdFALSE;
  
  	while( ( UCA1IFG & UCRXIFG ) != 0 )
  	{
  		/* Get the character from the UART and post it on the queue of Rxed
  		characters. */
  		cChar = UCA1RXBUF;
  		xQueueSendFromISR( xRxedChars, &cChar, &xHigherPriorityTaskWoken );
  	}
  	
  	/* If there is a Tx interrupt pending and the tx interrupts are enabled. */
  	if( ( UCA1IFG & UCTXIFG ) != 0 )
  	{
  		/* The previous character has been transmitted.  See if there are any
  		further characters waiting transmission. */
  		if( xQueueReceiveFromISR( xCharsForTx, &cChar, &xHigherPriorityTaskWoken ) == pdTRUE )
  		{
  			/* There was another character queued - transmit it now. */
  			UCA1TXBUF = cChar;
  		}
  		else
  		{
  			/* There were no other characters to transmit - disable the Tx
  			interrupt. */
  			UCA1IE &= ~UCTXIE;
  		}
  	}
  
  	__bic_SR_register_on_exit( SCG1 + SCG0 + OSCOFF + CPUOFF );
  	
  	/* If writing to a queue caused a task to unblock, and the unblocked task
  	has a priority equal to or above the task that this interrupt interrupted,
  	then lHigherPriorityTaskWoken will have been set to pdTRUE internally within
  	xQueuesendFromISR(), and portEND_SWITCHING_ISR() will ensure that this
  	interrupt returns directly to the higher priority unblocked task.
  	
  	THIS MUST BE THE LAST THING DONE IN THE ISR. */	
  	portYIELD_FROM_ISR( xHigherPriorityTaskWoken );
  }
  
  
  