/*
	FreeRTOS V5.4.1 - 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.
*/

/* 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 portCHAR ) 0x20 )
#define portCLOCK_DIV_64				( ( unsigned portCHAR ) 0x03 )
#define portCLOCK_DIV					( ( unsigned portLONG ) 64 )
#define portTGRA_INTERRUPT_ENABLE		( ( unsigned portCHAR ) 0x01 )
#define portTIMER_CHANNEL				( ( unsigned portCHAR ) 0x02 )
#define portMSTP13						( ( unsigned portSHORT ) 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 portLONG ulValue;

	/* This requires an even address. */
	ulValue = ( unsigned portLONG ) 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 portLONG ) 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 portLONG ) 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 portLONG 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;
}
/*-----------------------------------------------------------*/