1/*
2 * FreeRTOS Kernel V11.1.0
3 * Copyright (C) 2021 Amazon.com, Inc. or its affiliates. All Rights Reserved.
4 *
5 * SPDX-License-Identifier: MIT
6 *
7 * Permission is hereby granted, free of charge, to any person obtaining a copy of
8 * this software and associated documentation files (the "Software"), to deal in
9 * the Software without restriction, including without limitation the rights to
10 * use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of
11 * the Software, and to permit persons to whom the Software is furnished to do so,
12 * subject to the following conditions:
13 *
14 * The above copyright notice and this permission notice shall be included in all
15 * copies or substantial portions of the Software.
16 *
17 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
18 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
19 * FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
20 * COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER
21 * IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
22 * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
23 *
24 * https://www.FreeRTOS.org
25 * https://github.com/FreeRTOS
26 *
27 */
28
29#include "FreeRTOSConfig.h"
30#include "portasm.h"
31
32
33.CODE
34
35/*
36 * The RTOS tick ISR.
37 *
38 * If the cooperative scheduler is in use this simply increments the tick
39 * count.
40 *
41 * If the preemptive scheduler is in use a context switch can also occur.
42 */
43_vTickISR:
44        portSAVE_CONTEXT
45
46        call    #_xTaskIncrementTick
47        cmp.w   #0x00, r15
48                jeq     _SkipContextSwitch
49        call    #_vTaskSwitchContext
50_SkipContextSwitch:
51        portRESTORE_CONTEXT
52/*-----------------------------------------------------------*/
53
54
55/*
56 * Manual context switch called by the portYIELD() macro.
57 */
58_vPortYield::
59
60        /* Mimic an interrupt by pushing the SR. */
61        push    SR
62
63        /* Now the SR is stacked we can disable interrupts. */
64        dint
65
66        /* Save the context of the current task. */
67        portSAVE_CONTEXT
68
69        /* Switch to the highest priority task that is ready to run. */
70        call    #_vTaskSwitchContext
71
72        /* Restore the context of the new task. */
73        portRESTORE_CONTEXT
74/*-----------------------------------------------------------*/
75
76
77/*
78 * Start off the scheduler by initialising the RTOS tick timer, then restoring
79 * the context of the first task.
80 */
81_xPortStartScheduler::
82
83        /* Setup the hardware to generate the tick.  Interrupts are disabled
84        when this function is called. */
85        call    #_prvSetupTimerInterrupt
86
87        /* Restore the context of the first task that is going to run. */
88        portRESTORE_CONTEXT
89/*-----------------------------------------------------------*/
90
91
92        /* Place the tick ISR in the correct vector. */
93        .VECTORS
94
95        .KEEP
96
97        ORG     TIMERA0_VECTOR
98        DW      _vTickISR
99
100
101
102        END
103
104