/*
	FreeRTOS.org V4.7.1 - Copyright (C) 2003-2008 Richard Barry.

	This file is part of the FreeRTOS.org distribution.

	FreeRTOS.org is free software; you can redistribute it and/or modify
	it under the terms of the GNU General Public License as published by
	the Free Software Foundation; either version 2 of the License, or
	(at your option) any later version.

	FreeRTOS.org 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.org; if not, write to the Free Software
	Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA

	A special exception to the GPL can be applied should you wish to distribute
	a combined work that includes FreeRTOS.org, without being obliged to provide
	the source code for any proprietary components.  See the licensing section
	of http://www.FreeRTOS.org for full details of how and when the exception
	can be applied.

	***************************************************************************

	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.

	***************************************************************************
*/

#include "FreeRTOS.h"
#include "task.h"
#include "mb91467d.h"

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

/* We require the address of the pxCurrentTCB variable, but don't want to know
any details of its type. */
typedef void tskTCB;
extern volatile tskTCB * volatile pxCurrentTCB;

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


 
#pragma asm
#macro  SaveContext
	 ORCCR #0x20								;Switch to user stack
	 ST RP,@-R15								;Store RP
	 STM0 (R7,R6,R5,R4,R3,R2,R1,R0)				;Store R7-R0
	 STM1 (R14,R13,R12,R11,R10,R9,R8)			;Store R14-R8
	 ST MDH, @-R15								;Store MDH
	 ST MDL, @-R15								;Store MDL
	 
	 ANDCCR #0xDF								;Switch back to system stack
	 LD @R15+,R0								;Store PC to R0 
	 ORCCR #0x20								;Switch to user stack
	 ST R0,@-R15								;Store PC to User stack
	 
	 ANDCCR #0xDF								;Switch back to system stack
	 LD @R15+,R0								;Store PS to R0
	 ORCCR #0x20								;Switch to user stack
	 ST R0,@-R15								;Store PS to User stack
	 
	 LDI #_pxCurrentTCB, R0						;Get pxCurrentTCB address
	 LD @R0, R0									;Get the pxCurrentTCB->pxTopOfStack address
	 ST R15,@R0									;Store USP to pxCurrentTCB->pxTopOfStack
	 
	 ANDCCR #0xDF								;Switch back to system stack for the rest of tick ISR
#endm

#macro RestoreContext
	 LDI #_pxCurrentTCB, R0						;Get pxCurrentTCB address
	 LD @R0, R0									;Get the pxCurrentTCB->pxTopOfStack address
	 ORCCR #0x20								;Switch to user stack
	 LD @R0, R15								;Restore USP from pxCurrentTCB->pxTopOfStack

	 LD @R15+,R0								;Store PS to R0
	 ANDCCR #0xDF								;Switch to system stack
	 ST R0,@-R15								;Store PS to system stack

	 ORCCR #0x20								;Switch to user stack
	 LD @R15+,R0								;Store PC to R0
	 ANDCCR #0xDF								;Switch to system stack
	 ST R0,@-R15								;Store PC to system stack

	 ORCCR #0x20								;Switch back to retreive the remaining context

	 LD @R15+, MDL								;Restore MDL
	 LD @R15+, MDH								;Restore MDH
	 LDM1 (R14,R13,R12,R11,R10,R9,R8)			;Restore R14-R8
	 LDM0 (R7,R6,R5,R4,R3,R2,R1,R0)				;Restore R7-R0
	 LD @R15+, RP								;Restore RP
	 
	 ANDCCR #0xDF								;Switch back to system stack for the rest of tick ISR
#endm
#pragma endasm

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

/*
 * Perform hardware setup to enable ticks from timer 1,
 */
static void prvSetupTimerInterrupt( void );
/*-----------------------------------------------------------*/

/* 
 * Initialise the stack of a task to look exactly as if a call to 
 * portSAVE_CONTEXT had been called.
 * 
 * See the header file portable.h.
 */
portSTACK_TYPE *pxPortInitialiseStack( portSTACK_TYPE *pxTopOfStack, pdTASK_CODE pxCode, void *pvParameters )
{
unsigned portSHORT usAddress;

	/* Place a few bytes of known values on the bottom of the stack. 
	This is just useful for debugging. */

	*pxTopOfStack = 0x11111111;
	pxTopOfStack--;
	*pxTopOfStack = 0x22222222;
	pxTopOfStack--;
	*pxTopOfStack = 0x33333333;
	pxTopOfStack--;

	/* This is a redundant push to the stack, it may be required if in some implentation of the compiler
	the parameter to the task is passed on to the stack rather than in R4 register*/
	*pxTopOfStack = (portSTACK_TYPE)(pvParameters);
	pxTopOfStack--;                  
    
	*pxTopOfStack = ( portSTACK_TYPE ) 0x00000000;	/* RP */
	pxTopOfStack--;

	*pxTopOfStack = ( portSTACK_TYPE ) 0x00007777;	/* R7 */
	pxTopOfStack--;
	*pxTopOfStack = ( portSTACK_TYPE ) 0x00006666;	/* R6 */
	pxTopOfStack--;
	*pxTopOfStack = ( portSTACK_TYPE ) 0x00005555;	/* R5 */
	pxTopOfStack--;
	
	/* In the current implemention of the compiler the first parameter to the task(or function) is passed
	via R4 parameter to the task, hennce the pvParameters pointer is copied in R4 regsiter. See compiler 
	manual section 4.6.2 for more information.*/
	*pxTopOfStack = ( portSTACK_TYPE ) (pvParameters);	/* R4 */
	pxTopOfStack--;
	*pxTopOfStack = ( portSTACK_TYPE ) 0x00003333;	/* R3 */
	pxTopOfStack--;
	*pxTopOfStack = ( portSTACK_TYPE ) 0x00002222;	/* R2 */
	pxTopOfStack--;
	*pxTopOfStack = ( portSTACK_TYPE ) 0x00001111;	/* R1 */
	pxTopOfStack--;
	*pxTopOfStack = ( portSTACK_TYPE ) 0x00000001;	/* R0 */
	pxTopOfStack--;
	
	*pxTopOfStack = ( portSTACK_TYPE ) 0x0000EEEE;	/* R14 */
	pxTopOfStack--;
	*pxTopOfStack = ( portSTACK_TYPE ) 0x0000DDDD;	/* R13 */
	pxTopOfStack--;
	*pxTopOfStack = ( portSTACK_TYPE ) 0x0000CCCC;	/* R12 */
	pxTopOfStack--;
	*pxTopOfStack = ( portSTACK_TYPE ) 0x0000BBBB;	/* R11 */
	pxTopOfStack--;
	*pxTopOfStack = ( portSTACK_TYPE ) 0x0000AAAA;	/* R10 */
	pxTopOfStack--;
	*pxTopOfStack = ( portSTACK_TYPE ) 0x00009999;	/* R9 */
	pxTopOfStack--;
	*pxTopOfStack = ( portSTACK_TYPE ) 0x00008888;	/* R8 */
	pxTopOfStack--;
	
	*pxTopOfStack = ( portSTACK_TYPE ) 0x11110000;	/* MDH */
	pxTopOfStack--;
	*pxTopOfStack = ( portSTACK_TYPE ) 0x22220000;	/* MDL */
	pxTopOfStack--;

	usAddress = ( unsigned portSHORT ) pxCode;
	*pxTopOfStack = ( portSTACK_TYPE ) usAddress ;	/* PC */
	pxTopOfStack--;
	 
    /* PS - User Mode, USP, ILM=31, Interrupts enabled */
	*pxTopOfStack = ( portSTACK_TYPE ) 0x001F0030;	/* PS */

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

portBASE_TYPE xPortStartScheduler( void )
{
	/* Setup the hardware to generate the tick. */
	prvSetupTimerInterrupt();

	/* Restore the context of the first task that is going to run. */
#pragma asm
	RestoreContext
#pragma endasm

	/* Simulate a function call end as generated by the compiler.  We will now
	jump to the start of the task the context of which we have just restored. */
	
	__asm(" reti ");


	/* Should not get here. */
	return pdTRUE;
}
/*-----------------------------------------------------------*/

void vPortEndScheduler( void )
{
	/* It is unlikely that the AVR port will get stopped.  If required simply
	disable the tick interrupt here. */
}
/*-----------------------------------------------------------*/

/*
 * Setup RLT0 to generate a tick interrupt.
 */
static void prvSetupTimerInterrupt( void )
{

	TMCSR0_CNTE=0;		/* Count Disable */
    TMCSR0_CSL=0x2;		/* CLKP/32 */
    TMCSR0_MOD=0;		/* Software trigger */
    TMCSR0_RELD=1;		/* Reload */
    
    TMCSR0_UF=0;		/* Clear underflow flag */
	//TMRLR0=0x1F3;		/* Tick = 1 ms*/ 
	TMRLR0=0x1387;		/* Tick = 10 ms*/ 
	TMCSR0_INTE=1;		/* Interrupt Enable */
	TMCSR0_CNTE=1;		/* Count Enable */
	TMCSR0_TRG=1;		/* Trigger */
	
    PORTEN = 0x3;		/* Port Enable */
}
/*-----------------------------------------------------------*/

#if configUSE_PREEMPTION == 1

	/* 
	 * Tick ISR for preemptive scheduler. The tick count is incremented 
	 * after the context is saved. Then the context is switched if required,
	 * at last the context of the task which is to be resume is restored.
	 */

	#pragma asm

	.global _ReloadTimer0_IRQHandler
	_ReloadTimer0_IRQHandler:

	ANDCCR #0xEF							;Disable Interrupts

	SaveContext								;Save context

	ORCCR #0x10								;Re-enable Interrupts

	LDI #0xFFFB,R1
	LDI #_tmcsr0, R0
	AND R1,@R0								;Clear RLT0 interrupt flag

	CALL32	 _vTaskIncrementTick,R12		;Increment Tick

	CALL32	 _vTaskSwitchContext,R12		;Switch context if required

	ANDCCR #0xEF							;Disable Interrupts

	RestoreContext							;Restore context

	ORCCR #0x10								;Re-enable Interrupts

	RETI

	#pragma endasm
	
#else
	
	/* 
	 * Tick ISR for the cooperative scheduler.  All this does is increment the
	 * tick count.  We don't need to switch context, this can only be done by
	 * manual calls to taskYIELD();
	 */
	__interrupt void ReloadTimer0_IRQHandler( void )
	{
		/* Clear RLT0 interrupt flag */
		TMCSR0_UF = 0; 
		vTaskIncrementTick();
	}

#endif

	/*
 	 * Manual context switch. We can use a __nosavereg attribute  as the context 
 	 * would be saved by PortSAVE_CONTEXT().  The context is switched and then 
 	 * the context of the new task is restored saved. 
 	 */
#pragma asm

	.global _vPortYieldDelayed
	_vPortYieldDelayed:

	ANDCCR #0xEF							;Disable Interrupts

	SaveContext								;Save context

	ORCCR #0x10								;Re-enable Interrupts

	LDI #_dicr, R0
	BANDL #0x0E, @R0						;Clear Delayed interrupt flag

	CALL32	 _vTaskSwitchContext,R12		;Switch context if required

	ANDCCR #0xEF							;Disable Interrupts

	RestoreContext							;Restore context

	ORCCR #0x10								;Re-enable Interrupts

	RETI

#pragma endasm

	/*
 	 * Manual context switch. We can use a __nosavereg attribute  as the context 
 	 * would be saved by PortSAVE_CONTEXT().  The context is switched and then 
 	 * the context of the new task is restored saved. 
 	 */
 	 
#pragma asm

	.global _vPortYield
	_vPortYield:

	SaveContext								;Save context

	CALL32	 _vTaskSwitchContext,R12		;Switch context if required

	RestoreContext							;Restore context
	
	RETI

#pragma endasm