/*
	FreeRTOS.org V5.3.0 - Copyright (C) 2003-2009 Richard Barry.

	This file is part of the FreeRTOS.org distribution.

	FreeRTOS.org 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.org without being obliged to provide
	the source code for any proprietary components.  Alternative commercial
	license and support terms are also available upon request.  See the 
	licensing section of http://www.FreeRTOS.org for full details.

	FreeRTOS.org 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
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	You should have received a copy of the GNU General Public License along
	with FreeRTOS.org; if not, write to the Free Software Foundation, Inc., 59
	Temple Place, Suite 330, Boston, MA  02111-1307  USA.


	***************************************************************************
	*                                                                         *
	* Get the FreeRTOS eBook!  See http://www.FreeRTOS.org/Documentation      *
	*                                                                         *
	* This is a concise, step by step, 'hands on' guide that describes both   *
	* general multitasking concepts and FreeRTOS specifics. It presents and   *
	* explains numerous examples that are written using the FreeRTOS API.     *
	* Full source code for all the examples is provided in an accompanying    *
	* .zip file.                                                              *
	*                                                                         *
	***************************************************************************

	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
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	http://www.SafeRTOS.com - A version that is certified for use in safety
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*/

/*
Changes from V1.00:
	
	+ Call to the more efficient portSWITCH_CONTEXT() replaces the call to 
	  taskYIELD() in the ISR.

Changes from V1.01:

	+ The semaphore task is not operational.  This does nothing but check
	  the semaphore from ISR functionality.
	+ ISR modified slightly so only Rx or Tx is serviced per ISR - not both.

Changes from V1.2.0:

	+ Change so Tx uses a DMA channel, and Rx uses an interrupt.

Changes from V1.2.3

	+ The function xPortInitMinimal() has been renamed to 
	  xSerialPortInitMinimal() and the function xPortInit() has been renamed
	  to xSerialPortInit().

Changes from V1.2.5

	+ Reverted back to the non-DMA serial port driver, with a slightly modified
	  ISR.  This is a better test of the scheduler mechanisms.
	+ A critical section is now used in vInterruptOn().
	+ Flag sTxInterruptOn has been added to the port structure.  This allows
	  checking of the interrupt enable status without performing any IO.

Changes from V2.0.0

	+ Use portTickType in place of unsigned pdLONG for delay periods.
	+ Slightly more efficient vSerialSendString() implementation.
	+ cQueueReieveFromISR() used in place of xQueueReceive() in ISR.
*/

#include <stdlib.h>
#include <dos.h>
#include "FreeRTOS.h"
#include "queue.h"
#include "task.h"
#include "portasm.h"
#include "semphr.h"

#define serMAX_PORTS			( ( unsigned portSHORT ) 2 )

#define serPORT_0_INT_REG		( 0xff44 )
#define serPORT_0_BAUD_REG		( 0xff88 )
#define serPORT_0_RX_REG		( 0xff86 )
#define serPORT_0_TX_REG		( 0xff84 )
#define serPORT_0_STATUS_REG	( 0xff82 )
#define serPORT_0_CTRL_REG		( 0xff80 )
#define serPORT_0_IRQ			( 0x14 )

#define serPORT_1_INT_REG		( 0xff42 )
#define serPORT_1_BAUD_REG		( 0xff18 )
#define serPORT_1_RX_REG		( 0xff16 )
#define serPORT_1_TX_REG		( 0xff14 )
#define serPORT_1_STATUS_REG	( 0xff12 )
#define serPORT_1_CTRL_REG		( 0xff10 )
#define serPORT_1_IRQ			( 0x11 )

#define serTX_EMPTY				( ( unsigned portSHORT ) 0x40 )
#define serRX_READY				( ( unsigned portSHORT ) 0x80 )

#define serRESET_PIC( usEOI_TYPE )	portOUTPUT_WORD( ( unsigned portSHORT ) 0xff22, usEOI_TYPE )
#define serTX_HOLD_EMPTY_INT		( ( unsigned portSHORT ) 0x100 )

#define serENABLE_INTERRUPTS		( ( unsigned portSHORT ) 0x80 )
#define serMODE						( ( unsigned portSHORT ) 0x01 )
#define serENABLE_TX_MACHINES		( ( unsigned portSHORT ) 0x40 )
#define serENABLE_RX_MACHINES		( ( unsigned portSHORT ) 0x20 )
#define serINTERRUPT_MASK			( ( unsigned portSHORT ) 0x08 )
#define serCLEAR_ALL_STATUS_BITS	( ( unsigned portSHORT ) 0x00 )
#define serINTERRUPT_PRIORITY		( ( unsigned portSHORT ) 0x01 ) /*< Just below the scheduler priority. */

#define serDONT_BLOCK				( ( portTickType ) 0 )

typedef enum
{ 
	serCOM1 = 0, 
	serCOM2, 
	serCOM3, 
	serCOM4, 
	serCOM5, 
	serCOM6, 
	serCOM7, 
	serCOM8 
} eCOMPort;

typedef enum 
{ 
	serNO_PARITY, 
	serODD_PARITY, 
	serEVEN_PARITY, 
	serMARK_PARITY, 
	serSPACE_PARITY 
} eParity;

typedef enum 
{ 
	serSTOP_1, 
	serSTOP_2 
} eStopBits;

typedef enum 
{ 
	serBITS_5, 
	serBITS_6, 
	serBITS_7, 
	serBITS_8 
} eDataBits;

typedef enum 
{ 
	ser50 = 0,
	ser75,		
	ser110,		
	ser134,		
	ser150,    
	ser200,
	ser300,		
	ser600,		
	ser1200,	
	ser1800,	
	ser2400,   
	ser4800,
	ser9600,		
	ser19200,	
	ser38400,	
	ser57600,	
	ser115200
} eBaud;

/* Must be same order as eBaud definitions. */
static const unsigned portSHORT usBaudRateDivisor[] = 
{
	0, /* Not sure if the first 6 are correct.  First cannot be used. */
	29127,
	19859,
	16302,
	14564,
	10923,	
	6879,
	3437,
	1718,
	1145,
	859,
	429,
	214,
	107,
	54,
	35,
	18
};


typedef struct xCOM_PORT
{
	/* Hardware parameters for this port. */
	portSHORT sTxInterruptOn;
	unsigned portSHORT usIntReg;
	unsigned portSHORT usBaudReg;
	unsigned portSHORT usRxReg;
	unsigned portSHORT usTxReg;
	unsigned portSHORT usStatusReg;
	unsigned portSHORT usCtrlReg;

	unsigned portSHORT usIRQVector;

	/* Queues used for communications with com test task. */
	xQueueHandle xRxedChars; 
	xQueueHandle xCharsForTx;

	/* This semaphore does nothing useful except test a feature of the
	scheduler. */
	xSemaphoreHandle xTestSem;

} xComPort;

static xComPort xPorts[ serMAX_PORTS ] = 
{
	{ pdFALSE, serPORT_0_INT_REG, serPORT_0_BAUD_REG, serPORT_0_RX_REG, serPORT_0_TX_REG, serPORT_0_STATUS_REG, serPORT_0_CTRL_REG, serPORT_0_IRQ, NULL, NULL, NULL },
	{ pdFALSE, serPORT_1_INT_REG, serPORT_1_BAUD_REG, serPORT_1_RX_REG, serPORT_1_TX_REG, serPORT_1_STATUS_REG, serPORT_1_CTRL_REG, serPORT_1_IRQ, NULL, NULL, NULL }
};

typedef xComPort * xComPortHandle;

/* These prototypes are repeated here so we don't have to include the serial header.  This allows
the xComPortHandle structure details to be private to this file. */
xComPortHandle xSerialPortInit( eCOMPort ePort, eBaud eWantedBaud, eParity eWantedParity, eDataBits eWantedDataBits, eStopBits eWantedStopBits, unsigned portBASE_TYPE uxBufferLength );
portBASE_TYPE xSerialGetChar( xComPortHandle pxPort, portCHAR *pcRxedChar, portTickType xBlockTime );
portBASE_TYPE xSerialPutChar( xComPortHandle pxPort, portCHAR cOutChar, portTickType xBlockTime );
void vSerialClose( xComPortHandle xPort );
portSHORT sSerialWaitForSemaphore( xComPortHandle xPort );
/*-----------------------------------------------------------*/

static portSHORT xComPortISR( xComPort * const pxPort );

#define vInterruptOn( pxPort, usInterrupt )										\
{																				\
unsigned portSHORT usIn;														\
																				\
	portENTER_CRITICAL();														\
	{																			\
		if( pxPort->sTxInterruptOn == pdFALSE )									\
		{																		\
			usIn = portINPUT_WORD( pxPort->usCtrlReg );							\
			portOUTPUT_WORD( pxPort->usCtrlReg, usIn | usInterrupt );			\
																				\
			pxPort->sTxInterruptOn = pdTRUE;									\
		}																		\
	}																			\
	portEXIT_CRITICAL();															\
}																				
/*-----------------------------------------------------------*/

#define vInterruptOff( pxPort, usInterrupt )									\
{																				\
	unsigned portSHORT usIn = portINPUT_WORD( pxPort->usCtrlReg );				\
	if( usIn & usInterrupt )													\
	{																			\
		portOUTPUT_WORD( pxPort->usCtrlReg, usIn & ~usInterrupt);				\
		pxPort->sTxInterruptOn = pdFALSE;										\
	}																			\
}
/*-----------------------------------------------------------*/


/* Define an interrupt handler for each port */
#define COM_IRQ_WRAPPER(N)										\
	static void __interrupt COM_IRQ##N##_WRAPPER( void )		\
	{															\
        if( xComPortISR( &( xPorts[##N##] ) ) )                 \
        {                                                       \
			portSWITCH_CONTEXT();                             \
		}                                                       \
	}

  

COM_IRQ_WRAPPER( 0 )
COM_IRQ_WRAPPER( 1 )

static pxISR xISRs[ serMAX_PORTS ] = 
{
	COM_IRQ0_WRAPPER, 
	COM_IRQ1_WRAPPER
};

/*-----------------------------------------------------------*/

xComPortHandle xSerialPortInit( eCOMPort ePort, eBaud eWantedBaud, eParity eWantedParity, eDataBits eWantedDataBits, eStopBits eWantedStopBits, unsigned portBASE_TYPE uxBufferLength )
{
unsigned portSHORT usPort;
xComPortHandle pxPort = NULL;

/* BAUDDIV = ( Microprocessor Clock / Baud Rate ) / 16 */

	/* Only n, 8, 1 is supported so these parameters are not required for this
	port. */
	( void ) eWantedParity;
	( void ) eWantedDataBits;
    ( void ) eWantedStopBits;

	/* Currently only n,8,1 is supported. */

	usPort = ( unsigned portSHORT ) ePort;
	
	if( usPort < serMAX_PORTS )
	{
		pxPort = &( xPorts[ usPort ] );

		portENTER_CRITICAL();
		{
			unsigned portSHORT usInWord;

			/* Create the queues used by the com test task. */
			pxPort->xRxedChars = xQueueCreate( uxBufferLength, ( unsigned portBASE_TYPE ) sizeof( portCHAR ) );
			pxPort->xCharsForTx = xQueueCreate( uxBufferLength, ( unsigned portBASE_TYPE ) sizeof( portCHAR ) );

			/* Create the test semaphore.  This does nothing useful except test a feature of the scheduler. */
			vSemaphoreCreateBinary( pxPort->xTestSem );

			/* There is no ISR here already to restore later. */
			_dos_setvect( ( portSHORT ) pxPort->usIRQVector, xISRs[ usPort ] );

			usInWord = portINPUT_WORD( pxPort->usIntReg );
			usInWord &= ~serINTERRUPT_MASK;
			usInWord |= serINTERRUPT_PRIORITY;
			portOUTPUT_WORD( pxPort->usIntReg, usInWord );

			portOUTPUT_WORD( pxPort->usBaudReg, usBaudRateDivisor[ eWantedBaud ] );
			portOUTPUT_WORD( pxPort->usCtrlReg, serENABLE_INTERRUPTS | serMODE | serENABLE_TX_MACHINES | serENABLE_RX_MACHINES );

			portOUTPUT_WORD( pxPort->usStatusReg, serCLEAR_ALL_STATUS_BITS );
		}
		portEXIT_CRITICAL();
	}

	return pxPort;
} /*lint !e715 Some parameters are not used as only a subset of the serial port functionality is currently implemented. */
/*-----------------------------------------------------------*/

void vSerialPutString( xComPortHandle pxPort, const portCHAR * const pcString, unsigned portSHORT usStringLength )
{
unsigned portSHORT usByte;
portCHAR *pcNextChar;

	pcNextChar = ( portCHAR * ) pcString;

	for( usByte = 0; usByte < usStringLength; usByte++ )
	{
		xQueueSend( pxPort->xCharsForTx, pcNextChar, serDONT_BLOCK );
		pcNextChar++;
	}

	vInterruptOn( pxPort, serTX_HOLD_EMPTY_INT );
}
/*-----------------------------------------------------------*/

portBASE_TYPE xSerialGetChar( xComPortHandle pxPort, portCHAR *pcRxedChar, portTickType xBlockTime )
{
	/* Get the next character from the buffer, note that this routine is only 
	called having checked that the is (at least) one to get */
	if( xQueueReceive( pxPort->xRxedChars, pcRxedChar, xBlockTime ) )
	{
		return pdTRUE;
	}
	else
	{
		return pdFALSE;
	}
}
/*-----------------------------------------------------------*/

portBASE_TYPE xSerialPutChar( xComPortHandle pxPort, portCHAR cOutChar, portTickType xBlockTime )
{
	if( xQueueSend( pxPort->xCharsForTx, &cOutChar, xBlockTime ) != pdPASS )
	{
		return pdFAIL;
	}

	vInterruptOn( pxPort, serTX_HOLD_EMPTY_INT );

	return pdPASS;
}
/*-----------------------------------------------------------*/

portBASE_TYPE xSerialWaitForSemaphore( xComPortHandle xPort )
{
const portTickType xBlockTime = ( portTickType ) 0xffff;

	/* This function does nothing interesting, but test the 
	semaphore from ISR mechanism. */
	return xSemaphoreTake( xPort->xTestSem, xBlockTime );
}
/*-----------------------------------------------------------*/

void vSerialClose( xComPortHandle xPort )
{
unsigned portSHORT usOutput;

	/* Turn off the interrupts.  We may also want to delete the queues and/or
	re-install the original ISR. */

	portENTER_CRITICAL();
	{
		usOutput = portINPUT_WORD( xPort->usCtrlReg );

		usOutput &= ~serENABLE_INTERRUPTS;
		usOutput &= ~serENABLE_TX_MACHINES;
		usOutput &= ~serENABLE_RX_MACHINES;
		portOUTPUT_WORD( xPort->usCtrlReg, usOutput );

		usOutput = portINPUT_WORD( xPort->usIntReg );
		usOutput |= serINTERRUPT_MASK;
		portOUTPUT_WORD( xPort->usIntReg, usOutput );
	}
	portEXIT_CRITICAL();
}
/*-----------------------------------------------------------*/

static portBASE_TYPE xComPortISR( xComPort * const pxPort )
{
unsigned portSHORT usStatusRegister;
portCHAR cChar;
portBASE_TYPE xHigherPriorityTaskWoken = pdFALSE, xContinue = pdTRUE;

	/* NOTE:  THIS IS NOT AN EFFICIENT ISR AS IT IS DESIGNED SOLELY TO TEST
	THE SCHEDULER FUNCTIONALITY.  REAL APPLICATIONS SHOULD NOT USE THIS
	FUNCTION. */


	while( xContinue == pdTRUE )
	{
		xContinue = pdFALSE;
		usStatusRegister = portINPUT_WORD( pxPort->usStatusReg );

		if( usStatusRegister & serRX_READY )
		{
			cChar = ( portCHAR ) portINPUT_WORD( pxPort->usRxReg );
			xQueueSendFromISR( pxPort->xRxedChars, &cChar, &xHigherPriorityTaskWoken );

			/* Also release the semaphore - this does nothing interesting and is just a test. */
			xSemaphoreGiveFromISR( pxPort->xTestSem, &xHigherPriorityTaskWoken );

			/* We have performed an action this cycle - there may be other to perform. */
			xContinue = pdTRUE;
		}

		if( pxPort->sTxInterruptOn && ( usStatusRegister & serTX_EMPTY ) )
		{
			if( xQueueReceiveFromISR( pxPort->xCharsForTx, &cChar, &xHigherPriorityTaskWoken ) == pdTRUE )
			{
				portOUTPUT_WORD( pxPort->usTxReg, ( unsigned portSHORT ) cChar );

				/* We have performed an action this cycle - there may be others to perform. */
				xContinue = pdTRUE;
			}
			else
			{
				/* Queue empty, nothing to send */
				vInterruptOff( pxPort, serTX_HOLD_EMPTY_INT );
			}
		}
	}

	serRESET_PIC( pxPort->usIRQVector );

	/* If posting to the queue woke a task that was blocked on the queue we may
	want to switch to the woken task - depending on its priority relative to
	the task interrupted by this ISR. */
	return xHigherPriorityTaskWoken;
}






