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;/*
; * FreeRTOS Kernel V10.3.0
; * Copyright (C) 2020 Amazon.com, Inc. or its affiliates. All Rights Reserved.
; *
; * 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.
; *
; * http://www.FreeRTOS.org
; * http://aws.amazon.com/freertos
; *
; * 1 tab == 4 spaces!
; */
INCLUDE portmacro.inc
IMPORT vApplicationIRQHandler
IMPORT vTaskSwitchContext
IMPORT ulPortYieldRequired
IMPORT ulPortInterruptNesting
IMPORT vTaskSwitchContext
IMPORT ulICCIAR
IMPORT ulICCEOIR
EXPORT FreeRTOS_SWI_Handler
EXPORT FreeRTOS_IRQ_Handler
EXPORT vPortRestoreTaskContext
ARM
AREA PORT_ASM, CODE, READONLY
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
; SVC handler is used to yield a task.
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
FreeRTOS_SWI_Handler
PRESERVE8
; Save the context of the current task and select a new task to run.
portSAVE_CONTEXT
LDR R0, =vTaskSwitchContext
BLX R0
portRESTORE_CONTEXT
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
; vPortRestoreTaskContext is used to start the scheduler.
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
vPortRestoreTaskContext
; Switch to system mode
CPS #SYS_MODE
portRESTORE_CONTEXT
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
; PL390 GIC interrupt handler
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
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, =ulICCIAR
LDR r0, [r2]
; Ensure bit 2 of the stack pointer is clear. r2 holds the bit 2 value for
; future use. _RB_ Does this ever actually need to be done provided the
; start of the stack is 8-byte aligned?
MOV r2, sp
AND r2, r2, #4
SUB sp, sp, r2
; Call the interrupt handler. r4 is pushed to maintain alignment.
PUSH {r0-r4, lr}
LDR r1, =vApplicationIRQHandler
BLX r1
POP {r0-r4, lr}
ADD sp, sp, r2
CPSID i
; Write the value read from ICCIAR to ICCEOIR
LDR r4, =ulICCEOIR
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.
LDR r0, =vTaskSwitchContext
BLX r0
; Restore the context of, and branch to, the task selected to execute next.
portRESTORE_CONTEXT
END
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