/*
	FreeRTOS V5.4.2 - 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.


	***************************************************************************
	*                                                                         *
	* Looking for a quick start?  Then check out the FreeRTOS eBook!          *
	* 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
	critical systems.

	http://www.OpenRTOS.com - Commercial support, development, porting,
	licensing and training services.
*/

/* Kernel includes. */
#include "FreeRTOS.h"
#include "task.h"


#define portINITIAL_FORMAT_VECTOR		( ( portSTACK_TYPE ) 0x4000 )

/* Supervisor mode set. */
#define portINITIAL_STATUS_REGISTER		( ( portSTACK_TYPE ) 0x2000)

/* The clock prescale into the timer peripheral. */
#define portPRESCALE_VALUE				( ( unsigned portCHAR ) 10 )

/* The clock frequency into the RTC. */
#define portRTC_CLOCK_HZ				( ( unsigned portLONG ) 1000 )

asm void interrupt VectorNumber_VL1swi vPortYieldISR( void );
static void prvSetupTimerInterrupt( void );

/* Used to keep track of the number of nested calls to taskENTER_CRITICAL().  This
will be set to 0 prior to the first task being started. */
static unsigned portLONG ulCriticalNesting = 0x9999UL;

/*-----------------------------------------------------------*/

portSTACK_TYPE *pxPortInitialiseStack( portSTACK_TYPE * pxTopOfStack, pdTASK_CODE pxCode, void *pvParameters )
{

unsigned portLONG ulOriginalA5;

	__asm{ MOVE.L A5, ulOriginalA5 };


	*pxTopOfStack = (portSTACK_TYPE) 0xDEADBEEF;
	pxTopOfStack--;

	/* Exception stack frame starts with the return address. */
	*pxTopOfStack = ( portSTACK_TYPE ) pxCode;
	pxTopOfStack--;

	*pxTopOfStack = ( portINITIAL_FORMAT_VECTOR << 16UL ) | ( portINITIAL_STATUS_REGISTER );
	pxTopOfStack--;

	*pxTopOfStack = ( portSTACK_TYPE ) 0x0; /*FP*/
	pxTopOfStack -= 14; /* A5 to D0. */

	/* Parameter in A0. */
	*( pxTopOfStack + 8 ) = ( portSTACK_TYPE ) pvParameters;

	/* A5 must be maintained as it is resurved by the compiler. */
	*( pxTopOfStack + 13 ) = ulOriginalA5;

	return pxTopOfStack;  
}
/*-----------------------------------------------------------*/

portBASE_TYPE xPortStartScheduler( void )
{
extern void vPortStartFirstTask( void );

	ulCriticalNesting = 0UL;

	/* Configure a timer to generate the tick interrupt. */
	prvSetupTimerInterrupt();

	/* Start the first task executing. */
	vPortStartFirstTask();

	return pdFALSE;
}
/*-----------------------------------------------------------*/

static void prvSetupTimerInterrupt( void )
{				
	/* Prescale by 1 - ie no prescale. */
	RTCSC |= 8;
	
	/* Compare match value. */
	RTCMOD = portRTC_CLOCK_HZ / configTICK_RATE_HZ;
	
	/* Enable the RTC to generate interrupts - interrupts are already disabled
	when this code executes. */
	RTCSC_RTIE = 1;
}
/*-----------------------------------------------------------*/

void vPortEndScheduler( void )
{
	/* Not implemented as there is nothing to return to. */
}
/*-----------------------------------------------------------*/

void vPortEnterCritical( void )
{
	if( ulCriticalNesting == 0UL )
	{
		/* Guard against context switches being pended simultaneously with a
		critical section being entered. */
		do
		{
			portDISABLE_INTERRUPTS();
			if( INTC_FRC == 0UL )
			{
				break;
			}

			portENABLE_INTERRUPTS();

		} while( 1 );
	}
	ulCriticalNesting++;
}
/*-----------------------------------------------------------*/

void vPortExitCritical( void )
{
	ulCriticalNesting--;
	if( ulCriticalNesting == 0 )
	{
		portENABLE_INTERRUPTS();
	}
}
/*-----------------------------------------------------------*/

void vPortYieldHandler( void )
{
unsigned portLONG ulSavedInterruptMask;

	ulSavedInterruptMask = portSET_INTERRUPT_MASK_FROM_ISR();
	{
		/* Note this will clear all forced interrupts - this is done for speed. */
		INTC_CFRC = 0x3E;
		vTaskSwitchContext();
	}
	portCLEAR_INTERRUPT_MASK_FROM_ISR( ulSavedInterruptMask );
}
/*-----------------------------------------------------------*/

void interrupt VectorNumber_Vrtc vPortTickISR( void )
{
unsigned portLONG ulSavedInterruptMask;

	/* Clear the interrupt. */
	RTCSC |= RTCSC_RTIF_MASK;

	/* Increment the RTOS tick. */
	ulSavedInterruptMask = portSET_INTERRUPT_MASK_FROM_ISR();
	{
		vTaskIncrementTick();
	}
	portCLEAR_INTERRUPT_MASK_FROM_ISR( ulSavedInterruptMask );

	/* If we are using the pre-emptive scheduler then also request a
	context switch as incrementing the tick could have unblocked a task. */
	#if configUSE_PREEMPTION == 1
	{
		taskYIELD();
	}
	#endif
}