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/*
FreeRTOS.org V5.1.0 - 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.
***************************************************************************
***************************************************************************
* *
* SAVE TIME AND MONEY! We can port FreeRTOS.org to your own hardware, *
* and even write all or part of your application on your behalf. *
* See http://www.OpenRTOS.com for details of the services we provide to *
* expedite your project. *
* *
***************************************************************************
***************************************************************************
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.
*/
/*
Change from V4.2.1:
+ Introduced usage of configKERNEL_INTERRUPT_PRIORITY macro to set the
interrupt priority used by the kernel.
*/
/*-----------------------------------------------------------
* Implementation of functions defined in portable.h for the ARM CM3 port.
*----------------------------------------------------------*/
/* Scheduler includes. */
#include "FreeRTOS.h"
#include "task.h"
/* Constants required to manipulate the NVIC. */
#define portNVIC_SYSTICK_CTRL ( ( volatile unsigned portLONG *) 0xe000e010 )
#define portNVIC_SYSTICK_LOAD ( ( volatile unsigned portLONG *) 0xe000e014 )
#define portNVIC_INT_CTRL ( ( volatile unsigned portLONG *) 0xe000ed04 )
#define portNVIC_SYSPRI2 ( ( volatile unsigned portLONG *) 0xe000ed20 )
#define portNVIC_SYSTICK_CLK 0x00000004
#define portNVIC_SYSTICK_INT 0x00000002
#define portNVIC_SYSTICK_ENABLE 0x00000001
#define portNVIC_PENDSVSET 0x10000000
#define portNVIC_PENDSV_PRI ( ( ( unsigned portLONG ) configKERNEL_INTERRUPT_PRIORITY ) << 16 )
#define portNVIC_SYSTICK_PRI ( ( ( unsigned portLONG ) configKERNEL_INTERRUPT_PRIORITY ) << 24 )
/* Constants required to set up the initial stack. */
#define portINITIAL_XPSR ( 0x01000000 )
/* For backward compatibility, ensure configKERNEL_INTERRUPT_PRIORITY is
defined. The value 255 should also ensure backward compatibility.
FreeRTOS.org versions prior to V4.3.0 did not include this definition. */
#ifndef configKERNEL_INTERRUPT_PRIORITY
#define configKERNEL_INTERRUPT_PRIORITY 0
#endif
/* Each task maintains its own interrupt status in the critical nesting
variable. */
static unsigned portBASE_TYPE uxCriticalNesting = 0xaaaaaaaa;
/*
* Setup the timer to generate the tick interrupts.
*/
static void prvSetupTimerInterrupt( void );
/*
* Exception handlers.
*/
void xPortSysTickHandler( void );
/*
* Start first task is a separate function so it can be tested in isolation.
*/
extern void vPortStartFirstTask( void );
/*-----------------------------------------------------------*/
/*
* See header file for description.
*/
portSTACK_TYPE *pxPortInitialiseStack( portSTACK_TYPE *pxTopOfStack, pdTASK_CODE pxCode, void *pvParameters )
{
/* Simulate the stack frame as it would be created by a context switch
interrupt. */
*pxTopOfStack = portINITIAL_XPSR; /* xPSR */
pxTopOfStack--;
*pxTopOfStack = ( portSTACK_TYPE ) pxCode; /* PC */
pxTopOfStack--;
*pxTopOfStack = 0; /* LR */
pxTopOfStack -= 5; /* R12, R3, R2 and R1. */
*pxTopOfStack = ( portSTACK_TYPE ) pvParameters; /* R0 */
pxTopOfStack -= 8; /* R11, R10, R9, R8, R7, R6, R5 and R4. */
return pxTopOfStack;
}
/*-----------------------------------------------------------*/
/*
* See header file for description.
*/
portBASE_TYPE xPortStartScheduler( void )
{
/* Make PendSV and SysTick the lowest priority interrupts. */
*(portNVIC_SYSPRI2) |= portNVIC_PENDSV_PRI;
*(portNVIC_SYSPRI2) |= portNVIC_SYSTICK_PRI;
/* Start the timer that generates the tick ISR. Interrupts are disabled
here already. */
prvSetupTimerInterrupt();
/* Initialise the critical nesting count ready for the first task. */
uxCriticalNesting = 0;
/* Start the first task. */
vPortStartFirstTask();
/* Should not get here! */
return 0;
}
/*-----------------------------------------------------------*/
void vPortEndScheduler( void )
{
/* It is unlikely that the CM3 port will require this function as there
is nothing to return to. */
}
/*-----------------------------------------------------------*/
void vPortYieldFromISR( void )
{
/* Set a PendSV to request a context switch. */
*(portNVIC_INT_CTRL) = portNVIC_PENDSVSET;
}
/*-----------------------------------------------------------*/
void vPortEnterCritical( void )
{
portDISABLE_INTERRUPTS();
uxCriticalNesting++;
}
/*-----------------------------------------------------------*/
void vPortExitCritical( void )
{
uxCriticalNesting--;
if( uxCriticalNesting == 0 )
{
portENABLE_INTERRUPTS();
}
}
/*-----------------------------------------------------------*/
void xPortSysTickHandler( void )
{
unsigned portLONG ulDummy;
/* If using preemption, also force a context switch. */
#if configUSE_PREEMPTION == 1
*(portNVIC_INT_CTRL) = portNVIC_PENDSVSET;
#endif
ulDummy = portSET_INTERRUPT_MASK_FROM_ISR();
{
vTaskIncrementTick();
}
portCLEAR_INTERRUPT_MASK_FROM_ISR( ulDummy );
}
/*-----------------------------------------------------------*/
/*
* Setup the systick timer to generate the tick interrupts at the required
* frequency.
*/
void prvSetupTimerInterrupt( void )
{
/* Configure SysTick to interrupt at the requested rate. */
*(portNVIC_SYSTICK_LOAD) = ( configCPU_CLOCK_HZ / configTICK_RATE_HZ ) - 1UL;
*(portNVIC_SYSTICK_CTRL) = portNVIC_SYSTICK_CLK | portNVIC_SYSTICK_INT | portNVIC_SYSTICK_ENABLE;
}
/*-----------------------------------------------------------*/
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