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FreeRTOS-Kernel/FreeRTOS/Source/portable/GCC/ARM_CA9/portASM.S

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/*
FreeRTOS V8.0.0:rc1 - Copyright (C) 2014 Real Time Engineers Ltd.
All rights reserved
***************************************************************************
* *
* 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!
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.
*/
.org 0
.text
.set SYS_MODE, 0x1f
.set SVC_MODE, 0x13
.set IRQ_MODE, 0x12
.extern _boot
.extern vTaskSwitchContext
.extern ulICCIAR
.extern ulICCEOIR
.global _vector_table
.global FIQInterrupt
.global Undefined
.global PrefetchAbortHandler
.global DataAbortInterrupt
.global FreeRTOS_IRQ_Handler
.global FreeRTOS_SWI_Handler
.section .vectors
_vector_table:
B _boot
B Undefined
ldr pc, _swi
B PrefetchAbortHandler
B DataAbortHandler
NOP /* Placeholder for address exception vector*/
LDR PC, _irq
B FIQHandler
_irq: .word FreeRTOS_IRQ_Handler
_swi: .word FreeRTOS_SWI_Handler
/******************************************************************************
* SVC handler is used to start the scheduler and yield a task.
*****************************************************************************/
FreeRTOS_SWI_Handler:
/* Save the context of the current task and select a new task to run. */
// portSAVE_CONTEXT
LDR R0, =vTaskSwitchContext
BLX R0
vPortRestoreTaskContext:
// portRESTORE_CONTEXT
FreeRTOS_IRQ_Handler:
/* Return to the interrupted instruction. */
SUB lr, lr, #4
/* Push the return address and SPSR. */
PUSH {lr}
MRS lr, SPSR
PUSH {lr}
/* Change to supervisor mode to allow reentry. */
CPS #SVC_MODE
/* Push used registers. */
PUSH {r0-r4, r12}
/* Increment nesting count. r3 holds the address of ulPortInterruptNesting
for future use. r1 holds the original ulPortInterruptNesting value for
future use. */
LDR r3, =ulPortInterruptNesting
LDR r1, [r3]
ADD r4, r1, #1
STR r4, [r3]
/* Read value from the interrupt acknowledge register, which is stored in r0
for future parameter and interrupt clearing use. */
LDR r2, ulICCIARConst
LDR r0, [r2]
/* Ensure bit 2 of the stack pointer is clear. r2 holds the bit 2 value for
future use. */
MOV r2, sp
AND r2, r2, #4
SUB sp, sp, r2
/* Call the interrupt handler. */
PUSH {r0-r3, lr}
BL vApplicationIRQHandler
POP {r0-r3, lr}
ADD sp, sp, r2
CPSID i
/* Write the value read from ICCIAR to ICCEOIR. */
LDR r4, ulICCEOIRConst
STR r0, [r4]
/* Restore the old nesting count. */
STR r1, [r3]
/* A context switch is never performed if the nesting count is not 0. */
CMP r1, #0
BNE exit_without_switch
/* Did the interrupt request a context switch? r1 holds the address of
ulPortYieldRequired and r0 the value of ulPortYieldRequired for future
use. */
LDR r1, =ulPortYieldRequired
LDR r0, [r1]
CMP r0, #0
BNE switch_before_exit
exit_without_switch:
/* No context switch. Restore used registers, LR_irq and SPSR before
returning. */
POP {r0-r4, r12}
CPS #IRQ_MODE
POP {LR}
MSR SPSR_cxsf, LR
POP {LR}
MOVS PC, LR
switch_before_exit:
/* A context swtich is to be performed. Clear the context switch pending
flag. */
MOV r0, #0
STR r0, [r1]
/* Restore used registers, LR-irq and SPSR before saving the context
to the task stack. */
POP {r0-r4, r12}
CPS #IRQ_MODE
POP {LR}
MSR SPSR_cxsf, LR
POP {LR}
// portSAVE_CONTEXT
/* Call the function that selects the new task to execute.
vTaskSwitchContext() if vTaskSwitchContext() uses LDRD or STRD
instructions, or 8 byte aligned stack allocated data. LR does not need
saving as a new LR will be loaded by portRESTORE_CONTEXT anyway. */
BL vTaskSwitchContext
/* Restore the context of, and branch to, the task selected to execute
next. */
// portRESTORE_CONTEXT
ulICCIARConst: .word ulICCIAR
ulICCEOIRConst: .word ulICCEOIR
Undefined:
B .
PrefetchAbortHandler:
B .
FIQHandler:
B .
DataAbortHandler:
B .
.end
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