/*
    FreeRTOS V6.0.0 - Copyright (C) 2009 Real Time Engineers Ltd.

    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.


    ***************************************************************************
    *                                                                         *
    * The FreeRTOS eBook and reference manual are available to purchase for a *
    * small fee. Help yourself get started quickly while also helping the     *
    * FreeRTOS project! 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
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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 short ) 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 short ) 0x40 )
#define serRX_READY				( ( unsigned short ) 0x80 )

#define serRESET_PIC( usEOI_TYPE )	portOUTPUT_WORD( ( unsigned short ) 0xff22, usEOI_TYPE )
#define serTX_HOLD_EMPTY_INT		( ( unsigned short ) 0x100 )

#define serENABLE_INTERRUPTS		( ( unsigned short ) 0x80 )
#define serMODE						( ( unsigned short ) 0x01 )
#define serENABLE_TX_MACHINES		( ( unsigned short ) 0x40 )
#define serENABLE_RX_MACHINES		( ( unsigned short ) 0x20 )
#define serINTERRUPT_MASK			( ( unsigned short ) 0x08 )
#define serCLEAR_ALL_STATUS_BITS	( ( unsigned short ) 0x00 )
#define serINTERRUPT_PRIORITY		( ( unsigned short ) 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 short 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. */
	short sTxInterruptOn;
	unsigned short usIntReg;
	unsigned short usBaudReg;
	unsigned short usRxReg;
	unsigned short usTxReg;
	unsigned short usStatusReg;
	unsigned short usCtrlReg;

	unsigned short 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, char *pcRxedChar, portTickType xBlockTime );
portBASE_TYPE xSerialPutChar( xComPortHandle pxPort, char cOutChar, portTickType xBlockTime );
void vSerialClose( xComPortHandle xPort );
short sSerialWaitForSemaphore( xComPortHandle xPort );
/*-----------------------------------------------------------*/

static short xComPortISR( xComPort * const pxPort );

#define vInterruptOn( pxPort, usInterrupt )										\
{																				\
unsigned short 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 short 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 short 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 short ) ePort;
	
	if( usPort < serMAX_PORTS )
	{
		pxPort = &( xPorts[ usPort ] );

		portENTER_CRITICAL();
		{
			unsigned short usInWord;

			/* Create the queues used by the com test task. */
			pxPort->xRxedChars = xQueueCreate( uxBufferLength, ( unsigned portBASE_TYPE ) sizeof( char ) );
			pxPort->xCharsForTx = xQueueCreate( uxBufferLength, ( unsigned portBASE_TYPE ) sizeof( char ) );

			/* 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( ( short ) 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 char * const pcString, unsigned short usStringLength )
{
unsigned short usByte;
char *pcNextChar;

	pcNextChar = ( char * ) 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, char *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, char 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 short 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 short usStatusRegister;
char 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 = ( char ) 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 short ) 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;
}