/*
    FreeRTOS V6.0.5 - Copyright (C) 2010 Real Time Engineers Ltd.

    ***************************************************************************
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    *                                                                         *
    * A pdf reference manual is also available.  Both are usually delivered   *
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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
    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 it 
    can be viewed here: http://www.freertos.org/a00114.html and also obtained 
    by writing to Richard Barry, contact details for whom are available on the
    FreeRTOS WEB site.

    1 tab == 4 spaces!

    http://www.FreeRTOS.org - Documentation, latest information, license and
    contact details.

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*/

/* Scheduler includes. */
#include "FreeRTOS.h"
#include "task.h"


/*-----------------------------------------------------------
 * Implementation of functions defined in portable.h for the H8S port.
 *----------------------------------------------------------*/


/*-----------------------------------------------------------*/

/* When the task starts interrupts should be enabled. */
#define portINITIAL_CCR			( ( portSTACK_TYPE ) 0x00 )

/* Hardware specific constants used to generate the RTOS tick from the TPU. */
#define portCLEAR_ON_TGRA_COMPARE_MATCH ( ( unsigned char ) 0x20 )
#define portCLOCK_DIV_64				( ( unsigned char ) 0x03 )
#define portCLOCK_DIV					( ( unsigned long ) 64 )
#define portTGRA_INTERRUPT_ENABLE		( ( unsigned char ) 0x01 )
#define portTIMER_CHANNEL				( ( unsigned char ) 0x02 )
#define portMSTP13						( ( unsigned short ) 0x2000 )

/*
 * Setup TPU channel one for the RTOS tick at the requested frequency.
 */
static void prvSetupTimerInterrupt( void );

/*
 * The ISR used by portYIELD(). This is installed as a trap handler.
 */
void vPortYield( void ) __attribute__ ( ( saveall, interrupt_handler ) );

/*-----------------------------------------------------------*/

/* 
 * See header file for description. 
 */
portSTACK_TYPE *pxPortInitialiseStack( portSTACK_TYPE *pxTopOfStack, pdTASK_CODE pxCode, void *pvParameters )
{
unsigned long ulValue;

	/* This requires an even address. */
	ulValue = ( unsigned long ) pxTopOfStack;
	if( ulValue & 1UL )
	{
		pxTopOfStack = pxTopOfStack - 1;
	}

	/* Place a few bytes of known values on the bottom of the stack. 
	This is just useful for debugging. */
	pxTopOfStack--;
	*pxTopOfStack = 0xaa;
	pxTopOfStack--;
	*pxTopOfStack = 0xbb;
	pxTopOfStack--;
	*pxTopOfStack = 0xcc;
	pxTopOfStack--;
	*pxTopOfStack = 0xdd;

	/* The initial stack mimics an interrupt stack.  First there is the program
	counter (24 bits). */
	ulValue = ( unsigned long ) pxCode;

	pxTopOfStack--;
	*pxTopOfStack = ( portSTACK_TYPE ) ( ulValue & 0xff );
	pxTopOfStack--;
	ulValue >>= 8UL;
	*pxTopOfStack = ( portSTACK_TYPE ) ( ulValue & 0xff );
	pxTopOfStack--;
	ulValue >>= 8UL;
	*pxTopOfStack = ( portSTACK_TYPE ) ( ulValue & 0xff );

	/* Followed by the CCR. */	
	pxTopOfStack--;
	*pxTopOfStack = portINITIAL_CCR;

	/* Next all the general purpose registers - with the parameters being passed
	in ER0.  The parameter order must match that used by the compiler when the
	"saveall" function attribute is used. */

	/* ER6 */
	pxTopOfStack--;
	*pxTopOfStack = 0x66;
	pxTopOfStack--;
	*pxTopOfStack = 0x66;
	pxTopOfStack--;
	*pxTopOfStack = 0x66;
	pxTopOfStack--;
	*pxTopOfStack = 0x66;
	
	/* ER0 */
	ulValue = ( unsigned long ) pvParameters;

	pxTopOfStack--;
	*pxTopOfStack = ( portSTACK_TYPE ) ( ulValue & 0xff );
	pxTopOfStack--;
	ulValue >>= 8UL;
	*pxTopOfStack = ( portSTACK_TYPE ) ( ulValue & 0xff );
	pxTopOfStack--;
	ulValue >>= 8UL;
	*pxTopOfStack = ( portSTACK_TYPE ) ( ulValue & 0xff );
	pxTopOfStack--;
	ulValue >>= 8UL;
	*pxTopOfStack = ( portSTACK_TYPE ) ( ulValue & 0xff );
	
	/* ER1 */
	pxTopOfStack--;
	*pxTopOfStack = 0x11;
	pxTopOfStack--;
	*pxTopOfStack = 0x11;
	pxTopOfStack--;
	*pxTopOfStack = 0x11;
	pxTopOfStack--;
	*pxTopOfStack = 0x11;

	/* ER2 */
	pxTopOfStack--;
	*pxTopOfStack = 0x22;
	pxTopOfStack--;
	*pxTopOfStack = 0x22;
	pxTopOfStack--;
	*pxTopOfStack = 0x22;
	pxTopOfStack--;
	*pxTopOfStack = 0x22;

	/* ER3 */
	pxTopOfStack--;
	*pxTopOfStack = 0x33;
	pxTopOfStack--;
	*pxTopOfStack = 0x33;
	pxTopOfStack--;
	*pxTopOfStack = 0x33;
	pxTopOfStack--;
	*pxTopOfStack = 0x33;

	/* ER4 */
	pxTopOfStack--;
	*pxTopOfStack = 0x44;
	pxTopOfStack--;
	*pxTopOfStack = 0x44;
	pxTopOfStack--;
	*pxTopOfStack = 0x44;
	pxTopOfStack--;
	*pxTopOfStack = 0x44;

	/* ER5 */
	pxTopOfStack--;
	*pxTopOfStack = 0x55;
	pxTopOfStack--;
	*pxTopOfStack = 0x55;
	pxTopOfStack--;
	*pxTopOfStack = 0x55;
	pxTopOfStack--;
	*pxTopOfStack = 0x55;

	return pxTopOfStack;
}
/*-----------------------------------------------------------*/

portBASE_TYPE xPortStartScheduler( void )
{
extern void * pxCurrentTCB;

	/* Setup the hardware to generate the tick. */
	prvSetupTimerInterrupt();

	/* Restore the context of the first task that is going to run.  This
	mirrors the function epilogue code generated by the compiler when the
	"saveall" function attribute is used. */
	asm volatile ( 
					"MOV.L		@_pxCurrentTCB, ER6			\n\t"
					"MOV.L		@ER6, ER7					\n\t"
					"LDM.L     	@SP+, (ER4-ER5)				\n\t"
					"LDM.L     	@SP+, (ER0-ER3)				\n\t"
					"MOV.L     	@ER7+, ER6					\n\t"
					"RTE									\n\t"
				);

	( void ) pxCurrentTCB;

	/* Should not get here. */
	return pdTRUE;
}
/*-----------------------------------------------------------*/

void vPortEndScheduler( void )
{
	/* It is unlikely that the h8 port will get stopped. */
}
/*-----------------------------------------------------------*/

/*
 * Manual context switch.  This is a trap handler.  The "saveall" function
 * attribute is used so the context is saved by the compiler prologue.  All
 * we have to do is save the stack pointer.
 */
void vPortYield( void )
{
	portSAVE_STACK_POINTER();
		vTaskSwitchContext();
	portRESTORE_STACK_POINTER();
}
/*-----------------------------------------------------------*/

/* 
 * The interrupt handler installed for the RTOS tick depends on whether the 
 * preemptive or cooperative scheduler is being used. 
 */
#if( configUSE_PREEMPTION == 1 )

	/* 
	 * The preemptive scheduler is used so the ISR calls vTaskSwitchContext().
	 * The function prologue saves the context so all we have to do is save
	 * the stack pointer.
	 */
	void vTickISR( void ) __attribute__ ( ( saveall, interrupt_handler ) );
	void vTickISR( void )
	{
		portSAVE_STACK_POINTER();
		
		vTaskIncrementTick();
		vTaskSwitchContext();

		/* Clear the interrupt. */
		TSR1 &= ~0x01;

		portRESTORE_STACK_POINTER();
	}

#else

	/*
	 * The cooperative scheduler is being used so all we have to do is 
	 * periodically increment the tick.  This can just be a normal ISR and
	 * the "saveall" attribute is not required.
	 */
	void vTickISR( void ) __attribute__ ( ( interrupt_handler ) );
	void vTickISR( void )
	{
		vTaskIncrementTick();

		/* Clear the interrupt. */
		TSR1 &= ~0x01;
	}

#endif
/*-----------------------------------------------------------*/

/*
 * Setup timer 1 compare match to generate a tick interrupt.
 */
static void prvSetupTimerInterrupt( void )
{
const unsigned long ulCompareMatch = ( configCPU_CLOCK_HZ / configTICK_RATE_HZ ) / portCLOCK_DIV;

	/* Turn the module on. */
	MSTPCR &= ~portMSTP13;

	/* Configure timer 1. */
	TCR1 = portCLEAR_ON_TGRA_COMPARE_MATCH | portCLOCK_DIV_64;

	/* Configure the compare match value for a tick of configTICK_RATE_HZ. */
	TGR1A = ulCompareMatch;

	/* Start the timer and enable the interrupt - we can do this here as 
	interrupts are globally disabled when this function is called. */
	TIER1 |= portTGRA_INTERRUPT_ENABLE;
	TSTR |= portTIMER_CHANNEL;
}
/*-----------------------------------------------------------*/