/*
    FreeRTOS V7.5.3 - Copyright (C) 2013 Real Time Engineers Ltd. 
    All rights reserved

    VISIT http://www.FreeRTOS.org TO ENSURE YOU ARE USING THE LATEST VERSION.

    ***************************************************************************
     *                                                                       *
     *    FreeRTOS provides completely free yet professionally developed,    *
     *    robust, strictly quality controlled, supported, and cross          *
     *    platform software that has become a de facto standard.             *
     *                                                                       *
     *    Help yourself get started quickly and support the FreeRTOS         *
     *    project by purchasing a FreeRTOS tutorial book, reference          *
     *    manual, or both from: http://www.FreeRTOS.org/Documentation        *
     *                                                                       *
     *    Thank you!                                                         *
     *                                                                       *
    ***************************************************************************

    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.  Full license text is available from the following
    link: http://www.freertos.org/a00114.html

    1 tab == 4 spaces!

    ***************************************************************************
     *                                                                       *
     *    Having a problem?  Start by reading the FAQ "My application does   *
     *    not run, what could be wrong?"                                     *
     *                                                                       *
     *    http://www.FreeRTOS.org/FAQHelp.html                               *
     *                                                                       *
    ***************************************************************************

    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, a DOS
    compatible FAT file system, and our tiny thread aware UDP/IP stack.

    http://www.OpenRTOS.com - Real Time Engineers ltd license FreeRTOS to High
    Integrity Systems to sell under the OpenRTOS brand.  Low cost OpenRTOS
    licenses offer ticketed support, indemnification and middleware.

    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.

    1 tab == 4 spaces!
*/


/* 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;
}
/*-----------------------------------------------------------*/