mirror of
https://github.com/FreeRTOS/FreeRTOS-Kernel.git
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228 lines
8.9 KiB
C
228 lines
8.9 KiB
C
/*
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* FreeRTOS Kernel <DEVELOPMENT BRANCH>
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* Copyright (C) 2021 Amazon.com, Inc. or its affiliates. All Rights Reserved.
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*
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* SPDX-License-Identifier: MIT
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*
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* Permission is hereby granted, free of charge, to any person obtaining a copy of
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* this software and associated documentation files (the "Software"), to deal in
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* the Software without restriction, including without limitation the rights to
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* use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of
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* the Software, and to permit persons to whom the Software is furnished to do so,
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* subject to the following conditions:
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*
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* The above copyright notice and this permission notice shall be included in all
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* copies or substantial portions of the Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
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* FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
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* COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER
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* IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
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* CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
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*
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* https://www.FreeRTOS.org
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* https://github.com/FreeRTOS
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*
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*/
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/*-----------------------------------------------------------
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* Components that can be compiled to either ARM or THUMB mode are
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* contained in port.c The ISR routines, which can only be compiled
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* to ARM mode, are contained in this file.
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*----------------------------------------------------------*/
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/*
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* Changes from V3.2.4
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*
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+ The assembler statements are now included in a single asm block rather
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+ than each line having its own asm block.
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*/
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/* Scheduler includes. */
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#include "FreeRTOS.h"
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#include "task.h"
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#include "AT91SAM7X256.h"
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/* Constants required to handle interrupts. */
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#define portTIMER_MATCH_ISR_BIT ( ( uint8_t ) 0x01 )
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#define portCLEAR_VIC_INTERRUPT ( ( uint32_t ) 0 )
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/* Constants required to handle critical sections. */
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#define portNO_CRITICAL_NESTING ( ( uint32_t ) 0 )
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volatile uint32_t ulCriticalNesting = 9999UL;
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/*-----------------------------------------------------------*/
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/* ISR to handle manual context switches (from a call to taskYIELD()). */
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void vPortYieldProcessor( void ) __attribute__( ( interrupt( "SWI" ), naked ) );
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/*
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* The scheduler can only be started from ARM mode, hence the inclusion of this
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* function here.
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*/
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void vPortISRStartFirstTask( void );
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/*-----------------------------------------------------------*/
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void vPortISRStartFirstTask( void )
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{
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/* Simply start the scheduler. This is included here as it can only be
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* called from ARM mode. */
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portRESTORE_CONTEXT();
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}
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/*-----------------------------------------------------------*/
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/*
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* Called by portYIELD() or taskYIELD() to manually force a context switch.
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*
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* When a context switch is performed from the task level the saved task
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* context is made to look as if it occurred from within the tick ISR. This
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* way the same restore context function can be used when restoring the context
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* saved from the ISR or that saved from a call to vPortYieldProcessor.
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*/
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void vPortYieldProcessor( void )
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{
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/* Within an IRQ ISR the link register has an offset from the true return
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* address, but an SWI ISR does not. Add the offset manually so the same
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* ISR return code can be used in both cases. */
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__asm volatile ( "ADD LR, LR, #4" );
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/* Perform the context switch. First save the context of the current task. */
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portSAVE_CONTEXT();
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/* Find the highest priority task that is ready to run. */
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vTaskSwitchContext();
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/* Restore the context of the new task. */
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portRESTORE_CONTEXT();
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}
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/*-----------------------------------------------------------*/
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/*
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* The ISR used for the scheduler tick depends on whether the cooperative or
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* the preemptive scheduler is being used.
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*/
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#if configUSE_PREEMPTION == 0
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/* The cooperative scheduler requires a normal IRQ service routine to
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* simply increment the system tick. */
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void vNonPreemptiveTick( void ) __attribute__( ( interrupt( "IRQ" ) ) );
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void vNonPreemptiveTick( void )
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{
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uint32_t ulDummy;
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/* Increment the tick count - which may wake some tasks but as the
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* preemptive scheduler is not being used any woken task is not given
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* processor time no matter what its priority. */
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xTaskIncrementTick();
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/* Clear the PIT interrupt. */
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ulDummy = AT91C_BASE_PITC->PITC_PIVR;
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/* End the interrupt in the AIC. */
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AT91C_BASE_AIC->AIC_EOICR = ulDummy;
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}
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#else /* if configUSE_PREEMPTION == 0 */
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/* The preemptive scheduler is defined as "naked" as the full context is
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* saved on entry as part of the context switch. */
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void vPreemptiveTick( void ) __attribute__( ( naked ) );
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void vPreemptiveTick( void )
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{
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/* Save the context of the current task. */
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portSAVE_CONTEXT();
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/* Increment the tick count - this may wake a task. */
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if( xTaskIncrementTick() != pdFALSE )
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{
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/* Find the highest priority task that is ready to run. */
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vTaskSwitchContext();
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}
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/* End the interrupt in the AIC. */
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AT91C_BASE_AIC->AIC_EOICR = AT91C_BASE_PITC->PITC_PIVR;
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portRESTORE_CONTEXT();
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}
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#endif /* if configUSE_PREEMPTION == 0 */
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/*-----------------------------------------------------------*/
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/*
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* The interrupt management utilities can only be called from ARM mode. When
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* THUMB_INTERWORK is defined the utilities are defined as functions here to
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* ensure a switch to ARM mode. When THUMB_INTERWORK is not defined then
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* the utilities are defined as macros in portmacro.h - as per other ports.
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*/
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void vPortDisableInterruptsFromThumb( void ) __attribute__( ( naked ) );
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void vPortEnableInterruptsFromThumb( void ) __attribute__( ( naked ) );
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void vPortDisableInterruptsFromThumb( void )
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{
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__asm volatile (
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"STMDB SP!, {R0} \n\t" /* Push R0. */
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"MRS R0, CPSR \n\t" /* Get CPSR. */
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"ORR R0, R0, #0xC0 \n\t" /* Disable IRQ, FIQ. */
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"MSR CPSR, R0 \n\t" /* Write back modified value. */
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"LDMIA SP!, {R0} \n\t" /* Pop R0. */
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"BX R14" ); /* Return back to thumb. */
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}
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void vPortEnableInterruptsFromThumb( void )
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{
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__asm volatile (
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"STMDB SP!, {R0} \n\t" /* Push R0. */
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"MRS R0, CPSR \n\t" /* Get CPSR. */
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"BIC R0, R0, #0xC0 \n\t" /* Enable IRQ, FIQ. */
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"MSR CPSR, R0 \n\t" /* Write back modified value. */
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"LDMIA SP!, {R0} \n\t" /* Pop R0. */
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"BX R14" ); /* Return back to thumb. */
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}
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/* The code generated by the GCC compiler uses the stack in different ways at
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* different optimisation levels. The interrupt flags can therefore not always
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* be saved to the stack. Instead the critical section nesting level is stored
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* in a variable, which is then saved as part of the stack context. */
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void vPortEnterCritical( void )
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{
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/* Disable interrupts as per portDISABLE_INTERRUPTS(); */
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__asm volatile (
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"STMDB SP!, {R0} \n\t" /* Push R0. */
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"MRS R0, CPSR \n\t" /* Get CPSR. */
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"ORR R0, R0, #0xC0 \n\t" /* Disable IRQ, FIQ. */
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"MSR CPSR, R0 \n\t" /* Write back modified value. */
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"LDMIA SP!, {R0}" ); /* Pop R0. */
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/* Now that interrupts are disabled, ulCriticalNesting can be accessed
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* directly. Increment ulCriticalNesting to keep a count of how many times
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* portENTER_CRITICAL() has been called. */
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ulCriticalNesting++;
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}
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void vPortExitCritical( void )
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{
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if( ulCriticalNesting > portNO_CRITICAL_NESTING )
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{
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/* Decrement the nesting count as we are leaving a critical section. */
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ulCriticalNesting--;
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/* If the nesting level has reached zero then interrupts should be
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* re-enabled. */
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if( ulCriticalNesting == portNO_CRITICAL_NESTING )
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{
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/* Enable interrupts as per portEXIT_CRITICAL(). */
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__asm volatile (
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"STMDB SP!, {R0} \n\t" /* Push R0. */
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"MRS R0, CPSR \n\t" /* Get CPSR. */
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"BIC R0, R0, #0xC0 \n\t" /* Enable IRQ, FIQ. */
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"MSR CPSR, R0 \n\t" /* Write back modified value. */
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"LDMIA SP!, {R0}" ); /* Pop R0. */
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}
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}
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}
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