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; V5.2.0 - Copyright (C) 2003-2009 Richard Barry.
; This file is part of the distribution.
; 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.
; 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 along
; with; if not, write to the Free Software Foundation, Inc., 59
; Temple Place, Suite 330, Boston, MA 02111-1307 USA.
; A special exception to the GPL is included to allow you to distribute a
; combined work that includes without being obliged to provide
; the source code for any proprietary components. See the licensing section
; of for full details.
; ***************************************************************************
; * *
; * Get the FreeRTOS eBook! See *
; * *
; * This is a concise, step by step, 'hands on' guide that describes both *
; * general multitasking concepts and FreeRTOS specifics. It presents and *
; * explains numerous examples that are written using the FreeRTOS API. *
; * Full source code for all the examples is provided in an accompanying *
; * .zip file. *
; * *
; ***************************************************************************
; 1 tab == 4 spaces!
; Please ensure to read the configuration and relevant port sections of the
; online documentation.
; - Documentation, latest information, license and
; contact details.
; - A version that is certified for use in safety
; critical systems.
; - Commercial support, development, porting,
; licensing and training services.
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.