/*
    FreeRTOS V7.4.0 - 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 itcan 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.
*/

/*
Changes from V1.2.3

	+ The function xPortInitMinimal() has been renamed to 
	  xSerialPortInitMinimal() and the function xPortInit() has been renamed
	  to xSerialPortInit().

Changes from V2.0.0

	+ Delay periods are now specified using variables and constants of
	  portTickType rather than unsigned long.
	+ xQueueReceiveFromISR() used in place of xQueueReceive() within the ISR.

Changes from V2.6.0

	+ Replaced the inb() and outb() functions with direct memory
	  access.  This allows the port to be built with the 20050414 build of
	  WinAVR.
*/

/* BASIC INTERRUPT DRIVEN SERIAL PORT DRIVER. */


#include <stdlib.h>
#include <avr/interrupt.h>
#include "FreeRTOS.h"
#include "queue.h"
#include "task.h"
#include "serial.h"

#define serBAUD_DIV_CONSTANT			( ( unsigned long ) 16 )

/* Constants for writing to UCSRB. */
#define serRX_INT_ENABLE				( ( unsigned char ) 0x80 )
#define serRX_ENABLE					( ( unsigned char ) 0x10 )
#define serTX_ENABLE					( ( unsigned char ) 0x08 )
#define serTX_INT_ENABLE				( ( unsigned char ) 0x20 )

/* Constants for writing to UCSRC. */
#define serUCSRC_SELECT					( ( unsigned char ) 0x80 )
#define serEIGHT_DATA_BITS				( ( unsigned char ) 0x06 )

static xQueueHandle xRxedChars; 
static xQueueHandle xCharsForTx; 

#define vInterruptOn()										\
{															\
	unsigned char ucByte;								\
															\
	ucByte = UCSRB;											\
	ucByte |= serTX_INT_ENABLE;								\
	UCSRB = ucByte;											\
}																				
/*-----------------------------------------------------------*/

#define vInterruptOff()										\
{															\
	unsigned char ucInByte;								\
															\
	ucInByte = UCSRB;										\
	ucInByte &= ~serTX_INT_ENABLE;							\
	UCSRB = ucInByte;										\
}
/*-----------------------------------------------------------*/

xComPortHandle xSerialPortInitMinimal( unsigned long ulWantedBaud, unsigned portBASE_TYPE uxQueueLength )
{
unsigned long ulBaudRateCounter;
unsigned char ucByte;

	portENTER_CRITICAL();
	{
		/* Create the queues used by the com test task. */
		xRxedChars = xQueueCreate( uxQueueLength, ( unsigned portBASE_TYPE ) sizeof( signed char ) );
		xCharsForTx = xQueueCreate( uxQueueLength, ( unsigned portBASE_TYPE ) sizeof( signed char ) );

		/* Calculate the baud rate register value from the equation in the
		data sheet. */
		ulBaudRateCounter = ( configCPU_CLOCK_HZ / ( serBAUD_DIV_CONSTANT * ulWantedBaud ) ) - ( unsigned long ) 1;

		/* Set the baud rate. */	
		ucByte = ( unsigned char ) ( ulBaudRateCounter & ( unsigned long ) 0xff );	
		UBRRL = ucByte;

		ulBaudRateCounter >>= ( unsigned long ) 8;
		ucByte = ( unsigned char ) ( ulBaudRateCounter & ( unsigned long ) 0xff );	
		UBRRH = ucByte;

		/* Enable the Rx interrupt.  The Tx interrupt will get enabled
		later. Also enable the Rx and Tx. */
		UCSRB = ( serRX_INT_ENABLE | serRX_ENABLE | serTX_ENABLE );

		/* Set the data bits to 8. */
		UCSRC = ( serUCSRC_SELECT | serEIGHT_DATA_BITS );
	}
	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 char *pcRxedChar, portTickType xBlockTime )
{
	/* Only one port is 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 pdTRUE;
	}
	else
	{
		return pdFALSE;
	}
}
/*-----------------------------------------------------------*/

signed portBASE_TYPE xSerialPutChar( xComPortHandle pxPort, signed char cOutChar, portTickType xBlockTime )
{
	/* Only one port is supported. */
	( void ) pxPort;

	/* Return false if after the block time there is no room on the Tx queue. */
	if( xQueueSend( xCharsForTx, &cOutChar, xBlockTime ) != pdPASS )
	{
		return pdFAIL;
	}

	vInterruptOn();

	return pdPASS;
}
/*-----------------------------------------------------------*/

void vSerialClose( xComPortHandle xPort )
{
unsigned char ucByte;

	/* The parameter is not used. */
	( void ) xPort;

	/* Turn off the interrupts.  We may also want to delete the queues and/or
	re-install the original ISR. */

	portENTER_CRITICAL();
	{
		vInterruptOff();
		ucByte = UCSRB;
		ucByte &= ~serRX_INT_ENABLE;
		UCSRB = ucByte;
	}
	portEXIT_CRITICAL();
}
/*-----------------------------------------------------------*/

SIGNAL( SIG_UART_RECV )
{
signed char cChar;
signed portBASE_TYPE xHigherPriorityTaskWoken = pdFALSE;

	/* Get the character and post it on the queue of Rxed characters.
	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. */
	cChar = UDR;

	xQueueSendFromISR( xRxedChars, &cChar, &xHigherPriorityTaskWoken );

	if( xHigherPriorityTaskWoken != pdFALSE )
	{
		taskYIELD();
	}
}
/*-----------------------------------------------------------*/

SIGNAL( SIG_UART_DATA )
{
signed char cChar, cTaskWoken;

	if( xQueueReceiveFromISR( xCharsForTx, &cChar, &cTaskWoken ) == pdTRUE )
	{
		/* Send the next character queued for Tx. */
		UDR = cChar;
	}
	else
	{
		/* Queue empty, nothing to send. */
		vInterruptOff();
	}
}