FreeRTOS-Kernel/Source/portable/IAR/78K0R/port.c

/*
	FreeRTOS.org V5.1.1 - Copyright (C) 2003-2009 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.

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	Please ensure to read the configuration and relevant port sections of the
	online documentation.

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*/

/* Standard includes. */
#include <stdlib.h>

/* Scheduler includes. */
#include "FreeRTOS.h"
#include "task.h"

#define portINITIAL_CRITICAL_NESTING  (( unsigned portSHORT ) 10)

/* default Initialization of the PSW for the task:
 *   1100011000000000
 *   ||||||||-------------- Fill byte
 *   |||||||--------------- Cary Flag cleared
 *   |||||----------------- In-service priority Flags set to low level
 *   ||||------------------ Register bank Select 0 Flag cleared
 *   |||------------------- Auxiliary Cary Flag cleared
 *   ||-------------------- Register bank Select 1 Flag cleared
 *   |--------------------- Zero Flag set
 *   ---------------------- Global Interrupt Flag set
 */
#define portPSW		  (( portSTACK_TYPE ) 0xC600)

/* 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;

/* Most ports implement critical sections by placing the interrupt flags on
 * the stack before disabling interrupts.  Exiting the critical section is then
 * simply a case of popping the flags from the stack.  As 78K0 IAR does not use
 * a frame pointer this cannot be done as modifying the stack will clobber all
 * the stack variables.  Instead each task maintains a count of the critical
 * section nesting depth.  Each time a critical section is entered the count is
 * incremented.  Each time a critical section is left the count is decremented -
 * with interrupts only being re-enabled if the count is zero.
 *
 * usCriticalNesting will get set to zero when the scheduler starts, but must
 * not be initialised to zero as this will cause problems during the startup
 * sequence. 
 */
volatile unsigned portSHORT usCriticalNesting = portINITIAL_CRITICAL_NESTING;
/*-----------------------------------------------------------*/

__interrupt void MD_INTTM05( void );

/*
 * Sets up the periodic ISR used for the RTOS tick.  This uses timer 0, but
 * could have alternatively used the watchdog timer or 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 portLONG *pxLocal;

/* 
 * The 78K0R/Kx3 automatically pushes the PSW then PC onto the stack before 
 * executing an ISR.  We want the stack to look just as if this has happened
 * so place a pointer to the start of the task on the stack first - followed
 * by the flags we want the task to use when it starts up. 
 */
#if configMEMORY_MODE == 1
	pxTopOfStack--;
	pxLocal =  (unsigned portLONG*) pxTopOfStack;
	*pxLocal = (unsigned portLONG) pvParameters;
	pxTopOfStack--; 

	/* dummy are on the stack cause there normaly the return adress of the funtion 
	 * is written. Can be a dummy cause the function will never end but only be
	 * yielded an reentered 
	 */        
	*pxTopOfStack = ( portSTACK_TYPE ) 0xcdcd;
	pxTopOfStack--;
	*pxTopOfStack = ( portSTACK_TYPE ) 0xcdcd;
	pxTopOfStack--;       
	pxTopOfStack--;

	/* task function start address */
	pxLocal =  (unsigned portLONG*) pxTopOfStack;
	*pxLocal = (unsigned portLONG) pxCode;
	pxTopOfStack--;

	/* write initial value of the PSW */
	*pxTopOfStack = portPSW;
	pxTopOfStack--;

	/* Next general purpose register AX */
	*pxTopOfStack = ( portSTACK_TYPE ) 0x1111; 
	pxTopOfStack--;

#else 

	pxTopOfStack--;

	/* task function start address */
	pxLocal =  (unsigned portLONG*) pxTopOfStack;
	*pxLocal = (unsigned portLONG) pxCode;
	pxTopOfStack--;

	/* write initial value of the PSW */
	*pxTopOfStack = portPSW;
	pxTopOfStack--;

	/* Next general purpose registers AX with the task function parameter start address */
	*pxTopOfStack = ( portSTACK_TYPE ) pvParameters;
	pxTopOfStack--;

#endif        

	*pxTopOfStack = ( portSTACK_TYPE ) 0x2222;
	pxTopOfStack--;

	/* save the CS and ES register */
	*pxTopOfStack = ( portSTACK_TYPE ) 0x0F00;
	pxTopOfStack--;

	/* Next the remaining general purpose registers DE and BC */
	*pxTopOfStack = ( portSTACK_TYPE ) 0xDEDE;
	pxTopOfStack--;
	*pxTopOfStack = ( portSTACK_TYPE ) 0xBCBC;
	pxTopOfStack--;
	*pxTopOfStack = ( portSTACK_TYPE ) portNO_CRITICAL_SECTION_NESTING;	

	/* 
	 * Return a pointer to the top of the stack we have generated so this can
	 * be stored in the task control block for the task.
	 */
	return pxTopOfStack;
}
/*-----------------------------------------------------------*/

portBASE_TYPE xPortStartScheduler( void )
{
	/* Setup the hardware to generate the tick.  Interrupts are disabled when
	this function is called. */
	prvSetupTimerInterrupt();

	/* Restore the context of the first task that is going to run. */
	vPortStart();

	/* Should not get here as the tasks are now running! */
	return pdTRUE;
}
/*-----------------------------------------------------------*/

void vPortEndScheduler( void )
{
	/* It is unlikely that the 78K0R/Kx3 port will get stopped.  If required simply
	disable the tick interrupt here. */
}
/*-----------------------------------------------------------*/

/*
 * Hardware initialisation to generate the RTOS tick.  This uses Channel 5 of 
 * the Timer Array Unit (TAU). Any other Channel could also be used. 
 */
static void prvSetupTimerInterrupt( void )
{
	/* First the Timer Array Unit has to be enabled */
	TAU0EN = 1;

	/* To configure the Timer Array Unit all Channels have to been stopped */
	TT0 = 0xff;

	/* Interrupt of Timer Array Unit Channel 5 disabled to set Interrupt Priority */
	TMMK05 = 1;

	/* Clear Timer Array Unit Channel 5 Interrupt Flag */	
	TMIF05 = 0;

	/* Set Timer Array Unit Channel 5  Interrupt Priority */
	TMPR005 = 0;
	TMPR105 = 0;

	/* Set Timer Array Unit Channel 5 Mode as Interval Timer */
	TMR05 = 0x0000;

	/* Set the compare match value according to the tick rate we want. */
	TDR05 = (portTickType) (configCPU_CLOCK_HZ / configTICK_RATE_HZ);

	/* Set Timer Array Unit Channel 5 Output Mode */
	TOM0 &= ~0x0020;

	/* Set Timer Array Unit Channel 5 Output Level */	
	TOL0 &= ~0x0020;

	/* Set Timer Array Unit Channel 5 Output Enable */	
	TOE0 &= ~0x0020;

	/* Interrupt of Timer Array Unit Channel 5 enabled */
	TMMK05 = 0;

	/* Set Timer Array Unit Channel 5 Start*/
	TS0 |= 0x0020;
}
/*-----------------------------------------------------------*/