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#include "FreeRTOSConfig.h"
29#include "portasm.h"
30
31    IMPORT xTaskIncrementTick
32    IMPORT vTaskSwitchContext
33    IMPORT vPortSetupTimerInterrupt
34
35    EXPORT vTickISR
36    EXPORT vPortYield
37    EXPORT xPortStartScheduler
38
39    RSEG CODE
40
41/*
42 * The RTOS tick ISR.
43 *
44 * If the cooperative scheduler is in use this simply increments the tick
45 * count.
46 *
47 * If the preemptive scheduler is in use a context switch can also occur.
48 */
49vTickISR:
50    portSAVE_CONTEXT
51
52    call    #xTaskIncrementTick
53    cmp.w   #0x0, R12
54    jeq     SkipContextSwitch
55    call    #vTaskSwitchContext
56SkipContextSwitch:
57
58    portRESTORE_CONTEXT
59/*-----------------------------------------------------------*/
60
61
62/*
63 * Manual context switch called by the portYIELD() macro.
64 */
65vPortYield:
66
67    /* Mimic an interrupt by pushing the SR. */
68    push    SR
69
70    /* Now the SR is stacked we can disable interrupts. */
71    dint
72
73    /* Save the context of the current task. */
74    portSAVE_CONTEXT
75
76    /* Switch to the highest priority task that is ready to run. */
77    call    #vTaskSwitchContext
78
79    /* Restore the context of the new task. */
80    portRESTORE_CONTEXT
81/*-----------------------------------------------------------*/
82
83
84/*
85 * Start off the scheduler by initialising the RTOS tick timer, then restoring
86 * the context of the first task.
87 */
88xPortStartScheduler:
89
90    /* Setup the hardware to generate the tick.  Interrupts are disabled
91    when this function is called. */
92    call    #vPortSetupTimerInterrupt
93
94    /* Restore the context of the first task that is going to run. */
95    portRESTORE_CONTEXT
96/*-----------------------------------------------------------*/
97
98
99    /* Install vTickISR as the timer A0 interrupt. */
100    ASEG
101    ORG 0xFFE0 + TIMERA0_VECTOR
102
103    _vTickISR_: DC16 vTickISR
104
105
106    END
107