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/*
FreeRTOS V5.4.2 - 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.
*/
/*-----------------------------------------------------------
* Implementation of functions defined in portable.h for the ARM7 port.
*
* Components that can be compiled to either ARM or THUMB mode are
* contained in this file. The ISR routines, which can only be compiled
* to ARM mode are contained in portISR.c.
*----------------------------------------------------------*/
/* Standard includes. */
#include <stdlib.h>
/* Scheduler includes. */
#include "FreeRTOS.h"
#include "task.h"
/* Constants required to setup the task context. */
#define portINITIAL_SPSR ( ( portSTACK_TYPE ) 0x1f ) /* System mode, ARM mode, interrupts enabled. */
#define portTHUMB_MODE_BIT ( ( portSTACK_TYPE ) 0x20 )
#define portINSTRUCTION_SIZE ( ( portSTACK_TYPE ) 4 )
#define portNO_CRITICAL_SECTION_NESTING ( ( portSTACK_TYPE ) 0 )
/* Constants required to setup the tick ISR. */
#define portENABLE_TIMER ( ( unsigned portCHAR ) 0x01 )
#define portPRESCALE_VALUE 0x00
#define portINTERRUPT_ON_MATCH ( ( unsigned portLONG ) 0x01 )
#define portRESET_COUNT_ON_MATCH ( ( unsigned portLONG ) 0x02 )
/* Constants required to setup the VIC for the tick ISR. */
#define portTIMER_VIC_CHANNEL ( ( unsigned portLONG ) 0x0004 )
#define portTIMER_VIC_CHANNEL_BIT ( ( unsigned portLONG ) 0x0010 )
#define portTIMER_VIC_ENABLE ( ( unsigned portLONG ) 0x0020 )
/*-----------------------------------------------------------*/
/* Setup the timer to generate the tick interrupts. */
static void prvSetupTimerInterrupt( void );
/*
* The scheduler can only be started from ARM mode, so
* vPortISRStartFirstSTask() is defined in portISR.c.
*/
extern void vPortISRStartFirstTask( void );
/*-----------------------------------------------------------*/
/*
* Initialise the stack of a task to look exactly as if a call to
* portSAVE_CONTEXT had been called.
*
* See header file for description.
*/
portSTACK_TYPE *pxPortInitialiseStack( portSTACK_TYPE *pxTopOfStack, pdTASK_CODE pxCode, void *pvParameters )
{
portSTACK_TYPE *pxOriginalTOS;
pxOriginalTOS = pxTopOfStack;
/* Setup the initial stack of the task. The stack is set exactly as
expected by the portRESTORE_CONTEXT() macro. */
/* First on the stack is the return address - which in this case is the
start of the task. The offset is added to make the return address appear
as it would within an IRQ ISR. */
*pxTopOfStack = ( portSTACK_TYPE ) pxCode + portINSTRUCTION_SIZE;
pxTopOfStack--;
*pxTopOfStack = ( portSTACK_TYPE ) 0x00000000; /* R14 */
pxTopOfStack--;
*pxTopOfStack = ( portSTACK_TYPE ) pxOriginalTOS; /* Stack used when task starts goes in R13. */
pxTopOfStack--;
*pxTopOfStack = ( portSTACK_TYPE ) 0x12121212; /* R12 */
pxTopOfStack--;
*pxTopOfStack = ( portSTACK_TYPE ) 0x11111111; /* R11 */
pxTopOfStack--;
*pxTopOfStack = ( portSTACK_TYPE ) 0x10101010; /* R10 */
pxTopOfStack--;
*pxTopOfStack = ( portSTACK_TYPE ) 0x09090909; /* R9 */
pxTopOfStack--;
*pxTopOfStack = ( portSTACK_TYPE ) 0x08080808; /* R8 */
pxTopOfStack--;
*pxTopOfStack = ( portSTACK_TYPE ) 0x07070707; /* R7 */
pxTopOfStack--;
*pxTopOfStack = ( portSTACK_TYPE ) 0x06060606; /* R6 */
pxTopOfStack--;
*pxTopOfStack = ( portSTACK_TYPE ) 0x05050505; /* R5 */
pxTopOfStack--;
*pxTopOfStack = ( portSTACK_TYPE ) 0x04040404; /* R4 */
pxTopOfStack--;
*pxTopOfStack = ( portSTACK_TYPE ) 0x03030303; /* R3 */
pxTopOfStack--;
*pxTopOfStack = ( portSTACK_TYPE ) 0x02020202; /* R2 */
pxTopOfStack--;
*pxTopOfStack = ( portSTACK_TYPE ) 0x01010101; /* R1 */
pxTopOfStack--;
/* When the task starts is will expect to find the function parameter in
R0. */
*pxTopOfStack = ( portSTACK_TYPE ) pvParameters; /* R0 */
pxTopOfStack--;
/* The last thing onto the stack is the status register, which is set for
system mode, with interrupts enabled. */
*pxTopOfStack = ( portSTACK_TYPE ) portINITIAL_SPSR;
#ifdef THUMB_INTERWORK
{
/* We want the task to start in thumb mode. */
*pxTopOfStack |= portTHUMB_MODE_BIT;
}
#endif
pxTopOfStack--;
/* Some optimisation levels use the stack differently to others. This
means the interrupt flags cannot always be stored on the stack and will
instead be stored in a variable, which is then saved as part of the
tasks context. */
*pxTopOfStack = portNO_CRITICAL_SECTION_NESTING;
return pxTopOfStack;
}
/*-----------------------------------------------------------*/
portBASE_TYPE xPortStartScheduler( void )
{
/* Start the timer that generates the tick ISR. Interrupts are disabled
here already. */
prvSetupTimerInterrupt();
/* Start the first task. */
vPortISRStartFirstTask();
/* Should not get here! */
return 0;
}
/*-----------------------------------------------------------*/
void vPortEndScheduler( void )
{
/* It is unlikely that the ARM port will require this function as there
is nothing to return to. */
}
/*-----------------------------------------------------------*/
/*
* Setup the timer 0 to generate the tick interrupts at the required frequency.
*/
static void prvSetupTimerInterrupt( void )
{
unsigned portLONG ulCompareMatch;
PCLKSEL0 = (PCLKSEL0 & (~(0x3<<2))) | (0x01 << 2);
T0TCR = 2; /* Stop and reset the timer */
T0CTCR = 0; /* Timer mode */
/* A 1ms tick does not require the use of the timer prescale. This is
defaulted to zero but can be used if necessary. */
T0PR = portPRESCALE_VALUE;
/* Calculate the match value required for our wanted tick rate. */
ulCompareMatch = configCPU_CLOCK_HZ / configTICK_RATE_HZ;
/* Protect against divide by zero. Using an if() statement still results
in a warning - hence the #if. */
#if portPRESCALE_VALUE != 0
{
ulCompareMatch /= ( portPRESCALE_VALUE + 1 );
}
#endif
T0MR1 = ulCompareMatch;
/* Generate tick with timer 0 compare match. */
T0MCR = (3 << 3); /* Reset timer on match and generate interrupt */
/* Setup the VIC for the timer. */
VICIntEnable = 0x00000010;
/* The ISR installed depends on whether the preemptive or cooperative
scheduler is being used. */
#if configUSE_PREEMPTION == 1
{
extern void ( vPreemptiveTick )( void );
VICVectAddr4 = ( portLONG ) vPreemptiveTick;
}
#else
{
extern void ( vNonPreemptiveTick )( void );
VICVectAddr4 = ( portLONG ) vNonPreemptiveTick;
}
#endif
VICVectCntl4 = 1;
/* Start the timer - interrupts are disabled when this function is called
so it is okay to do this here. */
T0TCR = portENABLE_TIMER;
}
/*-----------------------------------------------------------*/