/*
    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       *
     *    the FreeRTOS project to continue with its mission of providing     *
     *    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?"                                     *
     *                                                                       *
     *    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, 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.   
 * 
 * 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;
	}
}