2 * FreeRTOS Kernel V10.1.1
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3 * Copyright (C) 2018 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.
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15 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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16 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
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17 * FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
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18 * COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER
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19 * IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
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20 * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
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22 * http://www.FreeRTOS.org
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23 * http://aws.amazon.com/freertos
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25 * 1 tab == 4 spaces!
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27 #include "FreeRTOSConfig.h"
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28 #include "portasm.h"
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30 IMPORT xTaskIncrementTick
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31 IMPORT vTaskSwitchContext
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32 IMPORT vPortSetupTimerInterrupt
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36 EXPORT xPortStartScheduler
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41 * The RTOS tick ISR.
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43 * If the cooperative scheduler is in use this simply increments the tick
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46 * If the preemptive scheduler is in use a context switch can also occur.
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51 call #xTaskIncrementTick
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53 jeq SkipContextSwitch
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54 call #vTaskSwitchContext
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58 /*-----------------------------------------------------------*/
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62 * Manual context switch called by the portYIELD() macro.
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66 /* Mimic an interrupt by pushing the SR. */
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69 /* Now the SR is stacked we can disable interrupts. */
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72 /* Save the context of the current task. */
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75 /* Switch to the highest priority task that is ready to run. */
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76 call #vTaskSwitchContext
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78 /* Restore the context of the new task. */
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80 /*-----------------------------------------------------------*/
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84 * Start off the scheduler by initialising the RTOS tick timer, then restoring
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85 * the context of the first task.
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87 xPortStartScheduler:
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89 /* Setup the hardware to generate the tick. Interrupts are disabled
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90 when this function is called. */
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91 call #vPortSetupTimerInterrupt
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93 /* Restore the context of the first task that is going to run. */
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95 /*-----------------------------------------------------------*/
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98 /* Install vTickISR as the timer A0 interrupt. */
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100 ORG 0xFFE0 + TIMERA0_VECTOR
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102 _vTickISR_: DC16 vTickISR
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