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/*

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

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

    *                                                                         *

    * If you are:                                                             *

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    *    + New to FreeRTOS,                                                   *

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    *                                                                         *

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    *        "Using the FreeRTOS Real Time Kernel - a Practical Guide"        *

    *                  http://www.FreeRTOS.org/Documentation                  *

    *                                                                         *

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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.

    1 tab == 4 spaces!

    http://www.FreeRTOS.org - Documentation, latest information, license and

    contact details.

    http://www.SafeRTOS.com - A version that is certified for use in safety

    critical systems.

    http://www.OpenRTOS.com - Commercial support, development, porting,

    licensing and training services.

*/

/* BASIC INTERRUPT DRIVEN SERIAL PORT DRIVER.

 *

 * This file only supports UART 0

 */

/* Standard includes. */

#include <stdlib.h>

/* Scheduler includes. */

#include "FreeRTOS.h"

#include "queue.h"

#include "task.h"

/* Demo application includes. */

#include "serial.h"

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

static xQueueHandle                     xRxedChars;

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

static xQueueHandle                     xCharsForTx;

static volatile portSHORT       sTHREEmpty;

static volatile portSHORT       queueFail = pdFALSE;

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

xComPortHandle xSerialPortInitMinimal( unsigned portLONG ulWantedBaud, unsigned portBASE_TYPE uxQueueLength )

{

        /* Initialise the hardware. */

        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) );

                if( xRxedChars == 0 )

                {

                        queueFail = pdTRUE;

                }

                if( xCharsForTx == 0 )

                {

                        queueFail = pdTRUE;

                }

                /* Initialize UART asynchronous mode */

                BGR0 = configCLKP1_CLOCK_HZ / ulWantedBaud;

                SCR0 = 0x17;    /* 8N1 */

                SMR0 = 0x0d;    /* enable SOT3, Reset, normal mode */

                SSR0 = 0x02;    /* LSB first, enable receive interrupts */

                PIER08_IE2 = 1; /* enable input */

                DDR08_D2 = 0;    /* switch P08_2 to input */

                DDR08_D3 = 1;   /* switch P08_3 to output */

        }

        portEXIT_CRITICAL();

        /* Unlike other ports, this serial code does not allow for more than one

        com port.  We therefore don't return a pointer to a port structure and can

        instead just return NULL. */

        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;

        /* Transmit a character. */

        portENTER_CRITICAL();

        {

                if( sTHREEmpty == pdTRUE )

                {

                        /* If sTHREEmpty is true then the UART Tx ISR has indicated that

                        there are no characters queued to be transmitted - so we can

                        write the character directly to the shift Tx register. */

                        sTHREEmpty = pdFALSE;

                        TDR0 = cOutChar;

                        xReturn = pdPASS;

                }

                else

                {

                        /* sTHREEmpty is false, so there are still characters waiting to be

                        transmitted.  We have to queue this character so it gets

                        transmitted     in turn. */

                        /* Return false if after the block time there is no room on the Tx

                        queue.  It is ok to block inside a critical section as each task

                        maintains it's own critical section status. */

                        if( xQueueSend(xCharsForTx, &cOutChar, xBlockTime) == pdTRUE )

                        {

                                xReturn = pdPASS;

                        }

                        else

                        {

                                xReturn = pdFAIL;

                        }

                }

                if( pdPASS == xReturn )

                {

                        /* Turn on the Tx interrupt so the ISR will remove the character from the

                        queue and send it.   This does not need to be in a critical section as

                        if the interrupt has already removed the character the next interrupt

                        will simply turn off the Tx interrupt again. */

                        SSR0_TIE = 1;

                }

        }

        portEXIT_CRITICAL();

        return pdPASS;

}

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

/*

 * UART RX interrupt service routine.

 */

__interrupt void UART0_RxISR( void )

{

volatile signed portCHAR        cChar;

portBASE_TYPE xHigherPriorityTaskWoken = pdFALSE;

        /* Get the character from the UART and post it on the queue of Rxed

        characters. */

        cChar = RDR0;

        xQueueSendFromISR( xRxedChars, ( const void *const ) &cChar, &xHigherPriorityTaskWoken );

        if( xHigherPriorityTaskWoken )

        {

                /*If the post causes a task to wake force a context switch

                as the woken task may have a higher priority than the task we have

                interrupted. */

                portYIELD_FROM_ISR();

        }

}

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

/*

 * UART Tx interrupt service routine.

 */

__interrupt void UART0_TxISR( void )

{

signed portCHAR                 cChar;

signed portBASE_TYPE    xTaskWoken = pdFALSE;

        /* 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. */

                TDR0 = cChar;

        }

        else

        {

                /* There were no other characters to transmit. */

                sTHREEmpty = pdTRUE;

                /* Disable transmit interrupts */

                SSR0_TIE = 0;

        }

}