2 * FreeRTOS Kernel V10.0.0
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3 * Copyright (C) 2017 Amazon.com, Inc. or its affiliates. All Rights Reserved.
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5 * Permission is hereby granted, free of charge, to any person obtaining a copy of
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6 * this software and associated documentation files (the "Software"), to deal in
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7 * the Software without restriction, including without limitation the rights to
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8 * use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of
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9 * the Software, and to permit persons to whom the Software is furnished to do so,
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10 * subject to the following conditions:
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12 * The above copyright notice and this permission notice shall be included in all
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13 * copies or substantial portions of the Software. If you wish to use our Amazon
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14 * FreeRTOS name, please do so in a fair use way that does not cause confusion.
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16 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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17 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
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18 * FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
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19 * COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER
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20 * IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
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21 * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
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23 * http://www.FreeRTOS.org
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24 * http://aws.amazon.com/freertos
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26 * 1 tab == 4 spaces!
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28 #include "FreeRTOSConfig.h"
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29 #include "portasm.h"
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31 IMPORT xTaskIncrementTick
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32 IMPORT vTaskSwitchContext
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33 IMPORT vPortSetupTimerInterrupt
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37 EXPORT xPortStartScheduler
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42 * The RTOS tick ISR.
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44 * If the cooperative scheduler is in use this simply increments the tick
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47 * If the preemptive scheduler is in use a context switch can also occur.
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52 call #xTaskIncrementTick
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54 jeq SkipContextSwitch
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55 call #vTaskSwitchContext
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59 /*-----------------------------------------------------------*/
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63 * Manual context switch called by the portYIELD() macro.
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67 /* Mimic an interrupt by pushing the SR. */
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70 /* Now the SR is stacked we can disable interrupts. */
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73 /* Save the context of the current task. */
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76 /* Switch to the highest priority task that is ready to run. */
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77 call #vTaskSwitchContext
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79 /* Restore the context of the new task. */
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81 /*-----------------------------------------------------------*/
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85 * Start off the scheduler by initialising the RTOS tick timer, then restoring
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86 * the context of the first task.
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88 xPortStartScheduler:
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90 /* Setup the hardware to generate the tick. Interrupts are disabled
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91 when this function is called. */
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92 call #vPortSetupTimerInterrupt
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94 /* Restore the context of the first task that is going to run. */
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96 /*-----------------------------------------------------------*/
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99 /* Install vTickISR as the timer A0 interrupt. */
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101 ORG 0xFFE0 + TIMERA0_VECTOR
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103 _vTickISR_: DC16 vTickISR
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