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;/*
; * FreeRTOS Kernel V10.4.3 LTS Patch 3
; * 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.
; *
; * https://www.FreeRTOS.org
; * https://github.com/FreeRTOS
; *
; * 1 tab == 4 spaces!
; */
INCLUDE portmacro.inc
IMPORT vTaskSwitchContext
IMPORT xTaskIncrementTick
EXPORT vPortYieldProcessor
EXPORT vPortStartFirstTask
EXPORT vPreemptiveTick
EXPORT vPortYield
VICVECTADDR EQU 0xFFFFF030
T0IR EQU 0xE0004000
T0MATCHBIT EQU 0x00000001
ARM
AREA PORT_ASM, CODE, READONLY
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
; Starting the first task is done by just restoring the context
; setup by pxPortInitialiseStack
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
vPortStartFirstTask
PRESERVE8
portRESTORE_CONTEXT
vPortYield
PRESERVE8
SVC 0
bx lr
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
; Interrupt service routine for the SWI interrupt. The vector table is
; configured in the startup.s file.
;
; vPortYieldProcessor() is used to manually force a context switch. The
; SWI interrupt is generated by a call to taskYIELD() or portYIELD().
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
vPortYieldProcessor
PRESERVE8
; Within an IRQ ISR the link register has an offset from the true return
; address, but an SWI ISR does not. Add the offset manually so the same
; ISR return code can be used in both cases.
ADD LR, LR, #4
; Perform the context switch.
portSAVE_CONTEXT ; Save current task context
LDR R0, =vTaskSwitchContext ; Get the address of the context switch function
MOV LR, PC ; Store the return address
BX R0 ; Call the contedxt switch function
portRESTORE_CONTEXT ; restore the context of the selected task
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
; Interrupt service routine for preemptive scheduler tick timer
; Only used if portUSE_PREEMPTION is set to 1 in portmacro.h
;
; Uses timer 0 of LPC21XX Family
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
vPreemptiveTick
PRESERVE8
portSAVE_CONTEXT ; Save the context of the current task.
LDR R0, =xTaskIncrementTick ; Increment the tick count.
MOV LR, PC ; This may make a delayed task ready
BX R0 ; to run.
CMP R0, #0
BEQ SkipContextSwitch
LDR R0, =vTaskSwitchContext ; Find the highest priority task that
MOV LR, PC ; is ready to run.
BX R0
SkipContextSwitch
MOV R0, #T0MATCHBIT ; Clear the timer event
LDR R1, =T0IR
STR R0, [R1]
LDR R0, =VICVECTADDR ; Acknowledge the interrupt
STR R0,[R0]
portRESTORE_CONTEXT ; Restore the context of the highest
; priority task that is ready to run.
END
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