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;/*
; FreeRTOS V8.0.0 - 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.
;*/
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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