2 ; * FreeRTOS Kernel V10.0.1
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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.
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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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30 EXTERN vTaskSwitchContext
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31 EXTERN xTaskIncrementTick
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33 PUBLIC vPortYieldProcessor
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34 PUBLIC vPortPreemptiveTick
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35 PUBLIC vPortStartFirstTask
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37 #include "AT91SAM7S64_inc.h"
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38 #include "ISR_Support.h"
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40 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
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41 ; Starting the first task is just a matter of restoring the context that
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42 ; was created by pxPortInitialiseStack().
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43 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
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44 vPortStartFirstTask:
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47 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
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48 ; Manual context switch function. This is the SWI hander.
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49 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
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50 vPortYieldProcessor:
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51 ADD LR, LR, #4 ; Add 4 to the LR to make the LR appear exactly
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52 ; as if the context was saved during and IRQ
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55 portSAVE_CONTEXT ; Save the context of the current task...
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56 LDR R0, =vTaskSwitchContext ; before selecting the next task to execute.
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59 portRESTORE_CONTEXT ; Restore the context of the selected task.
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61 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
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62 ; Preemptive context switch function. This will only ever get installed if
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63 ; portUSE_PREEMPTION is set to 1 in portmacro.h.
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64 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
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65 vPortPreemptiveTick:
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66 portSAVE_CONTEXT ; Save the context of the current task.
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68 LDR R0, =xTaskIncrementTick ; Increment the tick count - this may wake a task.
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73 BEQ SkipContextSwitch
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74 LDR R0, =vTaskSwitchContext ; Select the next task to execute.
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78 LDR R14, =AT91C_BASE_PITC ; Clear the PIT interrupt
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79 LDR R0, [R14, #PITC_PIVR ]
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81 LDR R14, =AT91C_BASE_AIC ; Mark the End of Interrupt on the AIC
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82 STR R14, [R14, #AIC_EOICR]
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84 portRESTORE_CONTEXT ; Restore the context of the selected task.
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