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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.

    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

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*/

/* BASIC INTERRUPT DRIVEN SERIAL PORT DRIVER FOR DEMO PURPOSES */

#include <stdlib.h>

#include "FreeRTOS.h"

#include "queue.h"

#include "task.h"

#include "serial.h"

/* Constants required to setup the serial control register. */

#define ser8_BIT_MODE                   ( ( unsigned char ) 0x40 )

#define serRX_ENABLE                    ( ( unsigned char ) 0x10 )

/* Constants to setup the timer used to generate the baud rate. */

#define serCLOCK_DIV_48                 ( ( unsigned char ) 0x03 )

#define serUSE_PRESCALED_CLOCK  ( ( unsigned char ) 0x10 )

#define ser8BIT_WITH_RELOAD             ( ( unsigned char ) 0x20 )

#define serSMOD                                 ( ( unsigned char ) 0x10 )

static xQueueHandle xRxedChars;

static xQueueHandle xCharsForTx;

data static unsigned portBASE_TYPE uxTxEmpty;

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

xComPortHandle xSerialPortInitMinimal( unsigned long ulWantedBaud, unsigned portBASE_TYPE uxQueueLength )

{

unsigned long ulReloadValue;

const portFLOAT fBaudConst = ( portFLOAT ) configCPU_CLOCK_HZ * ( portFLOAT ) 2.0;

unsigned char ucOriginalSFRPage;

        portENTER_CRITICAL();

        {

                ucOriginalSFRPage = SFRPAGE;

                SFRPAGE = 0;

                uxTxEmpty = pdTRUE;

                /* Create the queues used by the com test task. */

                xRxedChars = xQueueCreate( uxQueueLength, ( unsigned portBASE_TYPE ) sizeof( char ) );

                xCharsForTx = xQueueCreate( uxQueueLength, ( unsigned portBASE_TYPE ) sizeof( char ) );

                /* Calculate the baud rate to use timer 1. */

                ulReloadValue = ( unsigned long ) ( ( ( portFLOAT ) 256 - ( fBaudConst / ( portFLOAT ) ( 32 * ulWantedBaud ) ) ) + ( portFLOAT ) 0.5 );

                /* Set timer one for desired mode of operation. */

                TMOD &= 0x08;

                TMOD |= ser8BIT_WITH_RELOAD;

                SSTA0 |= serSMOD;

                /* Set the reload and start values for the time. */

                TL1 = ( unsigned char ) ulReloadValue;

                TH1 = ( unsigned char ) ulReloadValue;

                /* Setup the control register for standard n, 8, 1 - variable baud rate. */

                SCON = ser8_BIT_MODE | serRX_ENABLE;

                /* Enable the serial port interrupts */

                ES = 1;

                /* Start the timer. */

                TR1 = 1;

                SFRPAGE = ucOriginalSFRPage;

        }

        portEXIT_CRITICAL();

        /* Unlike some 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;

}

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

void vSerialISR( void ) interrupt 4

{

char cChar;

portBASE_TYPE xHigherPriorityTaskWoken = pdFALSE;

        /* 8051 port interrupt routines MUST be placed within a critical section

        if taskYIELD() is used within the ISR! */

        portENTER_CRITICAL();

        {

                if( RI )

                {

                        /* Get the character and post it on the queue of Rxed characters.

                        If the post causes a task to wake force a context switch if the woken task

                        has a higher priority than the task we have interrupted. */

                        cChar = SBUF;

                        RI = 0;

                        xQueueSendFromISR( xRxedChars, &cChar, &xHigherPriorityTaskWoken );

                }

                if( TI )

                {

                        if( xQueueReceiveFromISR( xCharsForTx, &cChar, &xHigherPriorityTaskWoken ) == ( portBASE_TYPE ) pdTRUE )

                        {

                                /* Send the next character queued for Tx. */

                                SBUF = cChar;

                        }

                        else

                        {

                                /* Queue empty, nothing to send. */

                                uxTxEmpty = pdTRUE;

                        }

                        TI = 0;

                }

                if( xHigherPriorityTaskWoken )

                {

                        portYIELD();

                }

        }

        portEXIT_CRITICAL();

}

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

portBASE_TYPE xSerialGetChar( xComPortHandle pxPort, signed char *pcRxedChar, portTickType xBlockTime )

{

        /* There is only one port supported. */

        ( 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 ( portBASE_TYPE ) pdTRUE;

        }

        else

        {

                return ( portBASE_TYPE ) pdFALSE;

        }

}

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

portBASE_TYPE xSerialPutChar( xComPortHandle pxPort, signed char cOutChar, portTickType xBlockTime )

{

portBASE_TYPE xReturn;

        /* There is only one port supported. */

        ( void ) pxPort;

        portENTER_CRITICAL();

        {

                if( uxTxEmpty == pdTRUE )

                {

                        SBUF = cOutChar;

                        uxTxEmpty = pdFALSE;

                        xReturn = ( portBASE_TYPE ) pdTRUE;

                }

                else

                {

                        xReturn = xQueueSend( xCharsForTx, &cOutChar, xBlockTime );

                        if( xReturn == ( portBASE_TYPE ) pdFALSE )

                        {

                                xReturn = ( portBASE_TYPE ) pdTRUE;

                        }

                }

        }

        portEXIT_CRITICAL();

        return xReturn;

}

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

void vSerialClose( xComPortHandle xPort )

{

        /* Not implemented in this port. */

        ( void ) xPort;

}

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