FreeRTOS-Kernel/Source/portable/GCC/ColdFire_V2/port.c

/*
    FreeRTOS V6.1.0 - Copyright (C) 2010 Real Time Engineers Ltd.

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    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
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    ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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    License and the FreeRTOS license exception along with FreeRTOS; if not it 
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*/

/* 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)

/* 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 long ulCriticalNesting = 0x9999UL;

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

portSTACK_TYPE *pxPortInitialiseStack( portSTACK_TYPE * pxTopOfStack, pdTASK_CODE pxCode, void *pvParameters )
{
	*pxTopOfStack = ( portSTACK_TYPE ) pvParameters;
	pxTopOfStack--;

	*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. */

    return pxTopOfStack;
}
/*-----------------------------------------------------------*/

portBASE_TYPE xPortStartScheduler( void )
{
extern void vPortStartFirstTask( void );

	ulCriticalNesting = 0UL;

	/* Configure the interrupts used by this port. */
	vApplicationSetupInterrupts();

	/* Start the first task executing. */
	vPortStartFirstTask();

	return pdFALSE;
}
/*-----------------------------------------------------------*/

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( MCF_INTC0_INTFRCL == 0UL )
			{
				break;
			}

			portENABLE_INTERRUPTS();

		} while( 1 );
	}
	ulCriticalNesting++;
}
/*-----------------------------------------------------------*/

void vPortExitCritical( void )
{
	ulCriticalNesting--;
	if( ulCriticalNesting == 0 )
	{
		portENABLE_INTERRUPTS();
	}
}
/*-----------------------------------------------------------*/

void vPortYieldHandler( void )
{
unsigned long ulSavedInterruptMask;

	ulSavedInterruptMask = portSET_INTERRUPT_MASK_FROM_ISR();
		/* Note this will clear all forced interrupts - this is done for speed. */
		MCF_INTC0_INTFRCL = 0;
		vTaskSwitchContext();
	portCLEAR_INTERRUPT_MASK_FROM_ISR( ulSavedInterruptMask );
}