2 FreeRTOS V8.2.2 - Copyright (C) 2015 Real Time Engineers Ltd.
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6 ***************************************************************************
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8 * FreeRTOS tutorial books are available in pdf and paperback. *
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9 * Complete, revised, and edited pdf reference manuals are also *
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12 * Purchasing FreeRTOS documentation will not only help you, by *
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13 * ensuring you get running as quickly as possible and with an *
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14 * in-depth knowledge of how to use FreeRTOS, it will also help *
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15 * the FreeRTOS project to continue with its mission of providing *
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16 * professional grade, cross platform, de facto standard solutions *
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17 * for microcontrollers - completely free of charge! *
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19 * >>> See http://www.FreeRTOS.org/Documentation for details. <<< *
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21 * Thank you for using FreeRTOS, and thank you for your support! *
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23 ***************************************************************************
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26 This file is part of the FreeRTOS distribution.
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28 FreeRTOS is free software; you can redistribute it and/or modify it under
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29 the terms of the GNU General Public License (version 2) as published by the
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30 Free Software Foundation AND MODIFIED BY the FreeRTOS exception.
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31 >>>NOTE<<< The modification to the GPL is included to allow you to
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32 distribute a combined work that includes FreeRTOS without being obliged to
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33 provide the source code for proprietary components outside of the FreeRTOS
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34 kernel. FreeRTOS is distributed in the hope that it will be useful, but
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35 WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
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36 or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
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37 more details. You should have received a copy of the GNU General Public
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38 License and the FreeRTOS license exception along with FreeRTOS; if not it
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39 can be viewed here: http://www.freertos.org/a00114.html and also obtained
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40 by writing to Richard Barry, contact details for whom are available on the
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45 http://www.FreeRTOS.org - Documentation, latest information, license and
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48 http://www.SafeRTOS.com - A version that is certified for use in safety
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51 http://www.OpenRTOS.com - Commercial support, development, porting,
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52 licensing and training services.
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55 #include "FreeRTOSConfig.h"
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57 SECTION .text:CODE:ROOT(2)
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60 /* Variables and functions. */
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62 EXTERN vTaskSwitchContext
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63 EXTERN vApplicationIRQHandler
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64 EXTERN ulPortInterruptNesting
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65 EXTERN ulPortTaskHasFPUContext
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66 EXTERN ulPortYieldRequired
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67 EXTERN ulCriticalNesting
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69 PUBLIC FreeRTOS_IRQ_Handler
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70 PUBLIC FreeRTOS_SVC_Handler
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71 PUBLIC vPortRestoreTaskContext
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77 portSAVE_CONTEXT MACRO
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79 /* Save the LR and SPSR onto the system mode stack before switching to
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80 system mode to save the remaining system mode registers. */
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81 SRSDB sp!, #SYS_MODE
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85 /* Push the critical nesting count. */
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86 LDR R2, =ulCriticalNesting
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90 /* Does the task have a floating point context that needs saving? If
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91 ulPortTaskHasFPUContext is 0 then no. */
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92 LDR R2, =ulPortTaskHasFPUContext
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96 /* Save the floating point context, if any. */
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99 #if configFPU_D32 == 1
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101 #endif /* configFPU_D32 */
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104 /* Save ulPortTaskHasFPUContext itself. */
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107 /* Save the stack pointer in the TCB. */
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108 LDR R0, =pxCurrentTCB
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114 ; /**********************************************************************/
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116 portRESTORE_CONTEXT MACRO
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118 /* Set the SP to point to the stack of the task being restored. */
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119 LDR R0, =pxCurrentTCB
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123 /* Is there a floating point context to restore? If the restored
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124 ulPortTaskHasFPUContext is zero then no. */
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125 LDR R0, =ulPortTaskHasFPUContext
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130 /* Restore the floating point context, if any. */
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132 #if configFPU_D32 == 1
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134 #endif /* configFPU_D32 */
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138 /* Restore the critical section nesting depth. */
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139 LDR R0, =ulCriticalNesting
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143 /* Restore all system mode registers other than the SP (which is already
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147 /* Return to the task code, loading CPSR on the way. */
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155 /******************************************************************************
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156 * SVC handler is used to yield.
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157 *****************************************************************************/
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158 FreeRTOS_SVC_Handler:
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159 /* Save the context of the current task and select a new task to run. */
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161 LDR R0, =vTaskSwitchContext
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163 portRESTORE_CONTEXT
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166 /******************************************************************************
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167 * vPortRestoreTaskContext is used to start the scheduler.
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168 *****************************************************************************/
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169 vPortRestoreTaskContext:
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170 /* Switch to system mode. */
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172 portRESTORE_CONTEXT
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174 FreeRTOS_IRQ_Handler:
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175 /* Return to the interrupted instruction. */
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178 /* Push the return address and SPSR. */
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183 /* Change to supervisor mode to allow reentry. */
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186 /* Push used registers. */
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189 /* Increment nesting count. r3 holds the address of ulPortInterruptNesting
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190 for future use. r1 holds the original ulPortInterruptNesting value for
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192 LDR r3, =ulPortInterruptNesting
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197 /* Ensure bit 2 of the stack pointer is clear. r2 holds the bit 2 value for
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203 /* Call the interrupt handler. */
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205 LDR r1, =vApplicationIRQHandler
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214 /* Write to the EOI register. */
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215 LDR r2, =configEOI_ADDRESS
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218 /* Restore the old nesting count. */
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221 /* A context switch is never performed if the nesting count is not 0. */
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223 BNE exit_without_switch
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225 /* Did the interrupt request a context switch? r1 holds the address of
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226 ulPortYieldRequired and r0 the value of ulPortYieldRequired for future
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228 LDR r1, =ulPortYieldRequired
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231 BNE switch_before_exit
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233 exit_without_switch:
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234 /* No context switch. Restore used registers, LR_irq and SPSR before
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243 switch_before_exit:
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244 /* A context swtich is to be performed. Clear the context switch pending
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249 /* Restore used registers, LR-irq and SPSR before saving the context
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250 to the task stack. */
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258 /* Call the function that selects the new task to execute.
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259 vTaskSwitchContext() if vTaskSwitchContext() uses LDRD or STRD
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260 instructions, or 8 byte aligned stack allocated data. LR does not need
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261 saving as a new LR will be loaded by portRESTORE_CONTEXT anyway. */
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262 LDR R0, =vTaskSwitchContext
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265 /* Restore the context of, and branch to, the task selected to execute
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267 portRESTORE_CONTEXT
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