2 ; FreeRTOS V7.4.2 - Copyright (C) 2013 Real Time Engineers Ltd.
\r
5 ; ***************************************************************************
\r
7 ; * FreeRTOS tutorial books are available in pdf and paperback. *
\r
8 ; * Complete, revised, and edited pdf reference manuals are also *
\r
11 ; * Purchasing FreeRTOS documentation will not only help you, by *
\r
12 ; * ensuring you get running as quickly as possible and with an *
\r
13 ; * in-depth knowledge of how to use FreeRTOS, it will also help *
\r
14 ; * the FreeRTOS project to continue with its mission of providing *
\r
15 ; * professional grade, cross platform, de facto standard solutions *
\r
16 ; * for microcontrollers - completely free of charge! *
\r
18 ; * >>> See http://www.FreeRTOS.org/Documentation for details. <<< *
\r
20 ; * Thank you for using FreeRTOS, and thank you for your support! *
\r
22 ; ***************************************************************************
\r
25 ; This file is part of the FreeRTOS distribution.
\r
27 ; FreeRTOS is free software; you can redistribute it and/or modify it under
\r
28 ; the terms of the GNU General Public License (version 2) as published by the
\r
29 ; Free Software Foundation AND MODIFIED BY the FreeRTOS exception.
\r
30 ; >>>NOTE<<< The modification to the GPL is included to allow you to
\r
31 ; distribute a combined work that includes FreeRTOS without being obliged to
\r
32 ; provide the source code for proprietary components outside of the FreeRTOS
\r
33 ; kernel. FreeRTOS is distributed in the hope that it will be useful, but
\r
34 ; WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
\r
35 ; or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
\r
36 ; more details. You should have received a copy of the GNU General Public
\r
37 ; License and the FreeRTOS license exception along with FreeRTOS; if not it
\r
38 ; can be viewed here: http://www.freertos.org/a00114.html and also obtained
\r
39 ; by writing to Richard Barry, contact details for whom are available on the
\r
40 ; FreeRTOS WEB site.
\r
42 ; 1 tab == 4 spaces!
\r
44 ; http://www.FreeRTOS.org - Documentation, latest information, license and
\r
47 ; http://www.SafeRTOS.com - A version that is certified for use in safety
\r
50 ; http://www.OpenRTOS.com - Commercial support, development, porting,
\r
51 ; licensing and training services.
\r
54 INCLUDE portmacro.inc
\r
56 IMPORT vTaskSwitchContext
\r
57 IMPORT xTaskIncrementTick
\r
59 EXPORT vPortYieldProcessor
\r
60 EXPORT vPortStartFirstTask
\r
61 EXPORT vPreemptiveTick
\r
65 VICVECTADDR EQU 0xFFFFF030
\r
67 T0MATCHBIT EQU 0x00000001
\r
70 AREA PORT_ASM, CODE, READONLY
\r
74 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
\r
75 ; Starting the first task is done by just restoring the context
\r
76 ; setup by pxPortInitialiseStack
\r
77 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
\r
91 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
\r
92 ; Interrupt service routine for the SWI interrupt. The vector table is
\r
93 ; configured in the startup.s file.
\r
95 ; vPortYieldProcessor() is used to manually force a context switch. The
\r
96 ; SWI interrupt is generated by a call to taskYIELD() or portYIELD().
\r
97 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
\r
103 ; Within an IRQ ISR the link register has an offset from the true return
\r
104 ; address, but an SWI ISR does not. Add the offset manually so the same
\r
105 ; ISR return code can be used in both cases.
\r
108 ; Perform the context switch.
\r
109 portSAVE_CONTEXT ; Save current task context
\r
110 LDR R0, =vTaskSwitchContext ; Get the address of the context switch function
\r
111 MOV LR, PC ; Store the return address
\r
112 BX R0 ; Call the contedxt switch function
\r
113 portRESTORE_CONTEXT ; restore the context of the selected task
\r
117 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
\r
118 ; Interrupt service routine for preemptive scheduler tick timer
\r
119 ; Only used if portUSE_PREEMPTION is set to 1 in portmacro.h
\r
121 ; Uses timer 0 of LPC21XX Family
\r
122 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
\r
128 portSAVE_CONTEXT ; Save the context of the current task.
\r
130 LDR R0, =xTaskIncrementTick ; Increment the tick count.
\r
131 MOV LR, PC ; This may make a delayed task ready
\r
134 LDR R0, =vTaskSwitchContext ; Find the highest priority task that
\r
135 MOV LR, PC ; is ready to run.
\r
138 MOV R0, #T0MATCHBIT ; Clear the timer event
\r
142 LDR R0, =VICVECTADDR ; Acknowledge the interrupt
\r
145 portRESTORE_CONTEXT ; Restore the context of the highest
\r
146 ; priority task that is ready to run.
\r