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/*
FreeRTOS V7.1.1 - Copyright (C) 2012 Real Time Engineers Ltd.
***************************************************************************
* *
* FreeRTOS tutorial books are available in pdf and paperback. *
* Complete, revised, and edited pdf reference manuals are also *
* available. *
* *
* Purchasing FreeRTOS documentation will not only help you, by *
* ensuring you get running as quickly as possible and with an *
* in-depth knowledge of how to use FreeRTOS, it will also help *
* the FreeRTOS project to continue with its mission of providing *
* professional grade, cross platform, de facto standard solutions *
* for microcontrollers - completely free of charge! *
* *
* >>> See http://www.FreeRTOS.org/Documentation for details. <<< *
* *
* Thank you for using FreeRTOS, and thank you for your support! *
* *
***************************************************************************
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 modification 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. 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 and the FreeRTOS license exception along with FreeRTOS; if not it
can be viewed here: http://www.freertos.org/a00114.html and also obtained
by writing to Richard Barry, contact details for whom are available on the
FreeRTOS WEB site.
1 tab == 4 spaces!
***************************************************************************
* *
* Having a problem? Start by reading the FAQ "My application does *
* not run, what could be wrong? *
* *
* http://www.FreeRTOS.org/FAQHelp.html *
* *
***************************************************************************
http://www.FreeRTOS.org - Documentation, training, latest information,
license and contact details.
http://www.FreeRTOS.org/plus - A selection of FreeRTOS ecosystem products,
including FreeRTOS+Trace - an indispensable productivity tool.
Real Time Engineers ltd license FreeRTOS to High Integrity Systems, who sell
the code with commercial support, indemnification, and middleware, under
the OpenRTOS brand: http://www.OpenRTOS.com. High Integrity Systems also
provide a safety engineered and independently SIL3 certified version under
the SafeRTOS brand: http://www.SafeRTOS.com.
*/
/*-----------------------------------------------------------
* Components that can be compiled to either ARM or THUMB mode are
* contained in port.c The ISR routines, which can only be compiled
* to ARM mode, are contained in this file.
*----------------------------------------------------------*/
/*
*/
/* Scheduler includes. */
#include "FreeRTOS.h"
#include "task.h"
/* Constants required to handle critical sections. */
#define portNO_CRITICAL_NESTING ( ( unsigned long ) 0 )
volatile unsigned long ulCriticalNesting = 9999UL;
/*-----------------------------------------------------------*/
/*
* The scheduler can only be started from ARM mode, hence the inclusion of this
* function here.
*/
void vPortISRStartFirstTask( void );
/*-----------------------------------------------------------*/
void vPortISRStartFirstTask( void )
{
/* Simply start the scheduler. This is included here as it can only be
called from ARM mode. */
asm volatile ( \
"LDR R0, =pxCurrentTCB \n\t" \
"LDR R0, [R0] \n\t" \
"LDR LR, [R0] \n\t" \
\
/* The critical nesting depth is the first item on the stack. */ \
/* Load it into the ulCriticalNesting variable. */ \
"LDR R0, =ulCriticalNesting \n\t" \
"LDMFD LR!, {R1} \n\t" \
"STR R1, [R0] \n\t" \
\
/* Get the SPSR from the stack. */ \
"LDMFD LR!, {R0} \n\t" \
"MSR SPSR, R0 \n\t" \
\
/* Restore all system mode registers for the task. */ \
"LDMFD LR, {R0-R14}^ \n\t" \
"NOP \n\t" \
\
/* Restore the return address. */ \
"LDR LR, [LR, #+60] \n\t" \
\
/* And return - correcting the offset in the LR to obtain the */ \
/* correct address. */ \
"SUBS PC, LR, #4 \n\t" \
);
}
/*-----------------------------------------------------------*/
void vPortTickISR( void )
{
/* Increment the RTOS tick count, then look for the highest priority
task that is ready to run. */
vTaskIncrementTick();
#if configUSE_PREEMPTION == 1
vTaskSwitchContext();
#endif
/* Ready for the next interrupt. */
TB_ClearITPendingBit( TB_IT_Update );
}
/*-----------------------------------------------------------*/
/*
* The interrupt management utilities can only be called from ARM mode. When
* THUMB_INTERWORK is defined the utilities are defined as functions here to
* ensure a switch to ARM mode. When THUMB_INTERWORK is not defined then
* the utilities are defined as macros in portmacro.h - as per other ports.
*/
#ifdef THUMB_INTERWORK
void vPortDisableInterruptsFromThumb( void ) __attribute__ ((naked));
void vPortEnableInterruptsFromThumb( void ) __attribute__ ((naked));
void vPortDisableInterruptsFromThumb( void )
{
asm volatile (
"STMDB SP!, {R0} \n\t" /* Push R0. */
"MRS R0, CPSR \n\t" /* Get CPSR. */
"ORR R0, R0, #0xC0 \n\t" /* Disable IRQ, FIQ. */
"MSR CPSR, R0 \n\t" /* Write back modified value. */
"LDMIA SP!, {R0} \n\t" /* Pop R0. */
"BX R14" ); /* Return back to thumb. */
}
void vPortEnableInterruptsFromThumb( void )
{
asm volatile (
"STMDB SP!, {R0} \n\t" /* Push R0. */
"MRS R0, CPSR \n\t" /* Get CPSR. */
"BIC R0, R0, #0xC0 \n\t" /* Enable IRQ, FIQ. */
"MSR CPSR, R0 \n\t" /* Write back modified value. */
"LDMIA SP!, {R0} \n\t" /* Pop R0. */
"BX R14" ); /* Return back to thumb. */
}
#endif /* THUMB_INTERWORK */
/*-----------------------------------------------------------*/
void vPortEnterCritical( void )
{
/* Disable interrupts as per portDISABLE_INTERRUPTS(); */
asm volatile (
"STMDB SP!, {R0} \n\t" /* Push R0. */
"MRS R0, CPSR \n\t" /* Get CPSR. */
"ORR R0, R0, #0xC0 \n\t" /* Disable IRQ, FIQ. */
"MSR CPSR, R0 \n\t" /* Write back modified value. */
"LDMIA SP!, {R0}" ); /* Pop R0. */
/* Now interrupts are disabled ulCriticalNesting can be accessed
directly. Increment ulCriticalNesting to keep a count of how many times
portENTER_CRITICAL() has been called. */
ulCriticalNesting++;
}
/*-----------------------------------------------------------*/
void vPortExitCritical( void )
{
if( ulCriticalNesting > portNO_CRITICAL_NESTING )
{
/* Decrement the nesting count as we are leaving a critical section. */
ulCriticalNesting--;
/* If the nesting level has reached zero then interrupts should be
re-enabled. */
if( ulCriticalNesting == portNO_CRITICAL_NESTING )
{
/* Enable interrupts as per portEXIT_CRITICAL(). */
asm volatile (
"STMDB SP!, {R0} \n\t" /* Push R0. */
"MRS R0, CPSR \n\t" /* Get CPSR. */
"BIC R0, R0, #0xC0 \n\t" /* Enable IRQ, FIQ. */
"MSR CPSR, R0 \n\t" /* Write back modified value. */
"LDMIA SP!, {R0}" ); /* Pop R0. */
}
}
}
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