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/*
FreeRTOS.org V5.1.2 - 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.
***************************************************************************
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.
***************************************************************************
*/
/*-----------------------------------------------------------
* 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;
}
/*-----------------------------------------------------------*/
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