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/*
* FreeRTOS Kernel V10.5.1
* Copyright (C) 2021 Amazon.com, Inc. or its affiliates. All Rights Reserved.
*
* SPDX-License-Identifier: MIT
*
* Permission is hereby granted, free of charge, to any person obtaining a copy of
* this software and associated documentation files (the "Software"), to deal in
* the Software without restriction, including without limitation the rights to
* use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of
* the Software, and to permit persons to whom the Software is furnished to do so,
* subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in all
* copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
* FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
* COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER
* IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
* CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
*
* https://www.FreeRTOS.org
* https://github.com/FreeRTOS
*
*/
/*-----------------------------------------------------------
* 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 ( ( uint32_t ) 0 )
volatile uint32_t 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. */
if( xTaskIncrementTick() != pdFALSE )
{
vTaskSwitchContext();
}
/* 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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