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; FreeRTOS V7.2.0 - Copyright (C) 2012 Real Time Engineers Ltd.
; ***************************************************************************
; * *
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; * available. *
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; ***************************************************************************
; 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: and also obtained
; by writing to Richard Barry, contact details for whom are available on the
; FreeRTOS WEB site.
; 1 tab == 4 spaces!
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IMPORT vTaskSwitchContext
IMPORT vTaskIncrementTick
EXPORT vPortYieldProcessor
EXPORT vPortStartFirstTask
EXPORT vPreemptiveTick
EXPORT vPortYield
T0IR EQU 0xE0004000
T0MATCHBIT EQU 0x00000001
; Starting the first task is done by just restoring the context
; setup by pxPortInitialiseStack
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().
; 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
portSAVE_CONTEXT ; Save the context of the current task.
LDR R0, =vTaskIncrementTick ; Increment the tick count.
MOV LR, PC ; This may make a delayed task ready
BX R0 ; to run.
LDR R0, =vTaskSwitchContext ; Find the highest priority task that
MOV LR, PC ; is ready to run.
MOV R0, #T0MATCHBIT ; Clear the timer event
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.