/*
	FreeRTOS V5.4.0 - Copyright (C) 2003-2009 Richard Barry.

	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.  
	Alternative commercial license and support terms are also available upon 
	request.  See the licensing section of http://www.FreeRTOS.org for full 
	license details.

	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 along
	with FreeRTOS; if not, write to the Free Software Foundation, Inc., 59
	Temple Place, Suite 330, Boston, MA  02111-1307  USA.


	***************************************************************************
	*                                                                         *
	* Looking for a quick start?  Then check out the FreeRTOS eBook!          *
	* See http://www.FreeRTOS.org/Documentation for details                   *
	*                                                                         *
	***************************************************************************

	1 tab == 4 spaces!

	Please ensure to read the configuration and relevant port sections of the
	online documentation.

	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 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 portCHAR ) 0x40 )
#define serRX_ENABLE			( ( unsigned portCHAR ) 0x10 )

/* Constants to setup the timer used to generate the baud rate. */
#define serCLOCK_DIV_48			( ( unsigned portCHAR ) 0x03 )
#define serUSE_PRESCALED_CLOCK	( ( unsigned portCHAR ) 0x10 )
#define ser8BIT_WITH_RELOAD		( ( unsigned portCHAR ) 0x20 )
#define serSMOD					( ( unsigned portCHAR ) 0x10 )

static xQueueHandle xRxedChars; 
static xQueueHandle xCharsForTx; 

data static unsigned portBASE_TYPE uxTxEmpty;

/*-----------------------------------------------------------*/

xComPortHandle xSerialPortInitMinimal( unsigned portLONG ulWantedBaud, unsigned portBASE_TYPE uxQueueLength )
{
unsigned portLONG ulReloadValue;
const portFLOAT fBaudConst = ( portFLOAT ) configCPU_CLOCK_HZ * ( portFLOAT ) 2.0;
unsigned portCHAR 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( portCHAR ) );
		xCharsForTx = xQueueCreate( uxQueueLength, ( unsigned portBASE_TYPE ) sizeof( portCHAR ) );
	
		/* Calculate the baud rate to use timer 1. */
		ulReloadValue = ( unsigned portLONG ) ( ( ( 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 portCHAR ) ulReloadValue;
		TH1 = ( unsigned portCHAR ) 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
{
portCHAR 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 portCHAR *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 portCHAR 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;
}
/*-----------------------------------------------------------*/