/*
    FreeRTOS V7.4.1 - Copyright (C) 2013 Real Time Engineers Ltd.

    FEATURES AND PORTS ARE ADDED TO FREERTOS ALL THE TIME.  PLEASE VISIT
    http://www.FreeRTOS.org TO ENSURE YOU ARE USING THE LATEST VERSION.

    ***************************************************************************
     *                                                                       *
     *    FreeRTOS tutorial books are available in pdf and paperback.        *
     *    Complete, revised, and edited pdf reference manuals are also       *
     *    available.                                                         *
     *                                                                       *
     *    Purchasing FreeRTOS documentation will not only help you, by       *
     *    ensuring you get running as quickly as possible and with an        *
     *    in-depth knowledge of how to use FreeRTOS, it will also help       *
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     *    professional grade, cross platform, de facto standard solutions    *
     *    for microcontrollers - completely free of charge!                  *
     *                                                                       *
     *    >>> See http://www.FreeRTOS.org/Documentation for details. <<<     *
     *                                                                       *
     *    Thank you for using FreeRTOS, and thank you for your support!      *
     *                                                                       *
    ***************************************************************************


    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.  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 Real Time Engineers Ltd., contact details for whom are available
    on the FreeRTOS WEB site.

    1 tab == 4 spaces!

    ***************************************************************************
     *                                                                       *
     *    Having a problem?  Start by reading the FAQ "My application does   *
     *    not run, what could be wrong?"                                     *
     *                                                                       *
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     *                                                                       *
    ***************************************************************************


    http://www.FreeRTOS.org - Documentation, books, training, latest versions, 
    license and Real Time Engineers Ltd. contact details.

    http://www.FreeRTOS.org/plus - A selection of FreeRTOS ecosystem products,
    including FreeRTOS+Trace - an indispensable productivity tool, and our new
    fully thread aware and reentrant UDP/IP stack.

    http://www.OpenRTOS.com - Real Time Engineers ltd license FreeRTOS to High 
    Integrity Systems, who sell the code with commercial support, 
    indemnification and middleware, under the OpenRTOS brand.
    
    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.
*/


/* 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;
}
/*-----------------------------------------------------------*/