port.c

FREERTOS的3.2.4版,关键是这个包里面含有FreeRTOS的官方网站的镜像,内含FreeRTOS的完全文档和好多种CPU的移植成果.

/*
	FreeRTOS V3.2.4 - Copyright (C) 2003-2005 Richard Barry.

	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 as published by
	the Free Software Foundation; either version 2 of the License, or
	(at your option) any later version.

	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

	A special exception to the GPL can be applied should you wish to distribute
	a combined work that includes FreeRTOS, 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.

	***************************************************************************
	See http://www.FreeRTOS.org for documentation, latest information, license 
	and contact details.  Please ensure to read the configuration and relevant 
	port sections of the online documentation.
	***************************************************************************
*/

/* 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 portSHORT usAddress;
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"	);
	asm volatile ( "MOV.L		@ER6, ER7"				);
	asm volatile ( "LDM.L     	@SP+, (ER4-ER5)"		);
	asm volatile ( "LDM.L     	@SP+, (ER0-ER3)"		);
	asm volatile ( "MOV.L     	@ER7+, ER6"				);
	asm volatile ( "RTE"								);

	/* 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;
}
/*-----------------------------------------------------------*/