/*
    FreeRTOS V7.5.3 - Copyright (C) 2013 Real Time Engineers Ltd. 
    All rights reserved

    VISIT http://www.FreeRTOS.org TO ENSURE YOU ARE USING THE LATEST VERSION.

    ***************************************************************************
     *                                                                       *
     *    FreeRTOS provides completely free yet professionally developed,    *
     *    robust, strictly quality controlled, supported, and cross          *
     *    platform software that has become a de facto standard.             *
     *                                                                       *
     *    Help yourself get started quickly and support the FreeRTOS         *
     *    project by purchasing a FreeRTOS tutorial book, reference          *
     *    manual, or both from: http://www.FreeRTOS.org/Documentation        *
     *                                                                       *
     *    Thank you!                                                         *
     *                                                                       *
    ***************************************************************************

    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 modification 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.  Full license text is available from the following
    link: http://www.freertos.org/a00114.html

    1 tab == 4 spaces!

    ***************************************************************************
     *                                                                       *
     *    Having a problem?  Start by reading the FAQ "My application does   *
     *    not run, what could be wrong?"                                     *
     *                                                                       *
     *    http://www.FreeRTOS.org/FAQHelp.html                               *
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    ***************************************************************************

    http://www.FreeRTOS.org - Documentation, books, training, latest versions,
    license and Real Time Engineers Ltd. contact details.

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    1 tab == 4 spaces!
*/

/* 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();
		
		if( xTaskIncrementTick() != pdFALSE )
		{
			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 )
	{
		xTaskIncrementTick();

		/* 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;
}
/*-----------------------------------------------------------*/