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/*

    FreeRTOS V6.1.1 - Copyright (C) 2011 Real Time Engineers Ltd.

    ***************************************************************************

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    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 exception 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.  See the GNU General Public License for

    more details. You should have received a copy of the GNU General Public

    License and the FreeRTOS license exception along with FreeRTOS; if not it

    can be viewed here: http://www.freertos.org/a00114.html and also obtained

    by writing to Richard Barry, contact details for whom are available on the

    FreeRTOS WEB site.

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*/

/* 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                             ( ( portTickType ) 0 )

/* The queue used to hold received characters. */

static xQueueHandle xRxedChars;

/* The queue used to hold characters waiting transmission. */

static xQueueHandle xCharsForTx;

/*-----------------------------------------------------------*/

xComPortHandle xSerialPortInitMinimal( unsigned portLONG ulWantedBaud, unsigned portBASE_TYPE uxQueueLength )

{

unsigned portLONG 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 portCHAR ) );

                xCharsForTx = xQueueCreate( uxQueueLength, ( unsigned portBASE_TYPE ) sizeof( signed portCHAR ) );

                /* Reset UART. */

                UCA1CTL1 |= UCSWRST;

                /* Use SMCLK. */

                UCA1CTL1 = UCSSEL0 | UCSSEL1;

                /* Setup baud rate low byte. */

                UCA1BR0 = ( unsigned portCHAR ) ( ulBaudRateCount & ( unsigned portLONG ) 0xff );

                /* Setup baud rate high byte. */

                ulBaudRateCount >>= 8UL;

                UCA1BR1 = ( unsigned portCHAR ) ( ulBaudRateCount & ( unsigned portLONG ) 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 portCHAR *pcRxedChar, portTickType 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 portCHAR cOutChar, portTickType 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;

}

/*-----------------------------------------------------------*/

#pragma vector=USCI_A1_VECTOR

static __interrupt void prvUSCI_A1_ISR( void )

{

signed portCHAR cChar;

portBASE_TYPE xTaskWoken = pdFALSE;

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, &xTaskWoken ) == 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 );

}