;/* | |
; FreeRTOS V6.0.0 - Copyright (C) 2009 Real Time Engineers Ltd. | |
; | |
; 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 exception 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. | |
; Alternative commercial license and support terms are also available upon | |
; request. See the licensing section of http://www.FreeRTOS.org for full | |
; license details. | |
; | |
; 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 along | |
; with FreeRTOS; if not, write to the Free Software Foundation, Inc., 59 | |
; Temple Place, Suite 330, Boston, MA 02111-1307 USA. | |
; | |
; | |
; *************************************************************************** | |
; * * | |
; * The FreeRTOS eBook and reference manual are available to purchase for a * | |
; * small fee. Help yourself get started quickly while also helping the * | |
; * FreeRTOS project! See http://www.FreeRTOS.org/Documentation for details * | |
; * * | |
; *************************************************************************** | |
; | |
; 1 tab == 4 spaces! | |
; | |
; Please ensure to read the configuration and relevant port sections of the | |
; online documentation. | |
; | |
; 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 vTaskIncrementTick | |
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, =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. | |
BX R0 | |
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 | |