2 ; * FreeRTOS Kernel V10.0.0
\r
3 ; * Copyright (C) 2017 Amazon.com, Inc. or its affiliates. All Rights Reserved.
\r
5 ; * Permission is hereby granted, free of charge, to any person obtaining a copy of
\r
6 ; * this software and associated documentation files (the "Software"), to deal in
\r
7 ; * the Software without restriction, including without limitation the rights to
\r
8 ; * use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of
\r
9 ; * the Software, and to permit persons to whom the Software is furnished to do so,
\r
10 ; * subject to the following conditions:
\r
12 ; * The above copyright notice and this permission notice shall be included in all
\r
13 ; * copies or substantial portions of the Software. If you wish to use our Amazon
\r
14 ; * FreeRTOS name, please do so in a fair use way that does not cause confusion.
\r
16 ; * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
\r
17 ; * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
\r
18 ; * FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
\r
19 ; * COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER
\r
20 ; * IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
\r
21 ; * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
\r
23 ; * http://www.FreeRTOS.org
\r
24 ; * http://aws.amazon.com/freertos
\r
26 ; * 1 tab == 4 spaces!
\r
29 INCLUDE portmacro.inc
\r
31 IMPORT vTaskSwitchContext
\r
32 IMPORT xTaskIncrementTick
\r
34 EXPORT vPortYieldProcessor
\r
35 EXPORT vPortStartFirstTask
\r
36 EXPORT vPreemptiveTick
\r
40 VICVECTADDR EQU 0xFFFFF030
\r
42 T0MATCHBIT EQU 0x00000001
\r
45 AREA PORT_ASM, CODE, READONLY
\r
49 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
\r
50 ; Starting the first task is done by just restoring the context
\r
51 ; setup by pxPortInitialiseStack
\r
52 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
\r
66 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
\r
67 ; Interrupt service routine for the SWI interrupt. The vector table is
\r
68 ; configured in the startup.s file.
\r
70 ; vPortYieldProcessor() is used to manually force a context switch. The
\r
71 ; SWI interrupt is generated by a call to taskYIELD() or portYIELD().
\r
72 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
\r
78 ; Within an IRQ ISR the link register has an offset from the true return
\r
79 ; address, but an SWI ISR does not. Add the offset manually so the same
\r
80 ; ISR return code can be used in both cases.
\r
83 ; Perform the context switch.
\r
84 portSAVE_CONTEXT ; Save current task context
\r
85 LDR R0, =vTaskSwitchContext ; Get the address of the context switch function
\r
86 MOV LR, PC ; Store the return address
\r
87 BX R0 ; Call the contedxt switch function
\r
88 portRESTORE_CONTEXT ; restore the context of the selected task
\r
92 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
\r
93 ; Interrupt service routine for preemptive scheduler tick timer
\r
94 ; Only used if portUSE_PREEMPTION is set to 1 in portmacro.h
\r
96 ; Uses timer 0 of LPC21XX Family
\r
97 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
\r
103 portSAVE_CONTEXT ; Save the context of the current task.
\r
105 LDR R0, =xTaskIncrementTick ; Increment the tick count.
\r
106 MOV LR, PC ; This may make a delayed task ready
\r
110 BEQ SkipContextSwitch
\r
111 LDR R0, =vTaskSwitchContext ; Find the highest priority task that
\r
112 MOV LR, PC ; is ready to run.
\r
115 MOV R0, #T0MATCHBIT ; Clear the timer event
\r
119 LDR R0, =VICVECTADDR ; Acknowledge the interrupt
\r
122 portRESTORE_CONTEXT ; Restore the context of the highest
\r
123 ; priority task that is ready to run.
\r