2 FreeRTOS V8.0.0:rc1 - Copyright (C) 2014 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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64 .extern vTaskSwitchContext
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68 .global _vector_table
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69 .global FIQInterrupt
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71 .global PrefetchAbortHandler
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72 .global DataAbortInterrupt
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73 .global FreeRTOS_IRQ_Handler
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74 .global FreeRTOS_SWI_Handler
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82 B PrefetchAbortHandler
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84 NOP /* Placeholder for address exception vector*/
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88 _irq: .word FreeRTOS_IRQ_Handler
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89 _swi: .word FreeRTOS_SWI_Handler
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91 /******************************************************************************
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92 * SVC handler is used to start the scheduler and yield a task.
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93 *****************************************************************************/
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94 FreeRTOS_SWI_Handler:
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96 /* Save the context of the current task and select a new task to run. */
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98 LDR R0, =vTaskSwitchContext
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101 vPortRestoreTaskContext:
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102 // portRESTORE_CONTEXT
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104 FreeRTOS_IRQ_Handler:
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105 /* Return to the interrupted instruction. */
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108 /* Push the return address and SPSR. */
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113 /* Change to supervisor mode to allow reentry. */
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116 /* Push used registers. */
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119 /* Increment nesting count. r3 holds the address of ulPortInterruptNesting
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120 for future use. r1 holds the original ulPortInterruptNesting value for
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122 LDR r3, =ulPortInterruptNesting
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127 /* Read value from the interrupt acknowledge register, which is stored in r0
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128 for future parameter and interrupt clearing use. */
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129 LDR r2, ulICCIARConst
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132 /* Ensure bit 2 of the stack pointer is clear. r2 holds the bit 2 value for
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138 /* Call the interrupt handler. */
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140 BL vApplicationIRQHandler
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146 /* Write the value read from ICCIAR to ICCEOIR. */
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147 LDR r4, ulICCEOIRConst
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150 /* Restore the old nesting count. */
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153 /* A context switch is never performed if the nesting count is not 0. */
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155 BNE exit_without_switch
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157 /* Did the interrupt request a context switch? r1 holds the address of
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158 ulPortYieldRequired and r0 the value of ulPortYieldRequired for future
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160 LDR r1, =ulPortYieldRequired
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163 BNE switch_before_exit
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165 exit_without_switch:
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166 /* No context switch. Restore used registers, LR_irq and SPSR before
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175 switch_before_exit:
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176 /* A context swtich is to be performed. Clear the context switch pending
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181 /* Restore used registers, LR-irq and SPSR before saving the context
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182 to the task stack. */
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188 // portSAVE_CONTEXT
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190 /* Call the function that selects the new task to execute.
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191 vTaskSwitchContext() if vTaskSwitchContext() uses LDRD or STRD
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192 instructions, or 8 byte aligned stack allocated data. LR does not need
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193 saving as a new LR will be loaded by portRESTORE_CONTEXT anyway. */
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194 BL vTaskSwitchContext
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196 /* Restore the context of, and branch to, the task selected to execute
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198 // portRESTORE_CONTEXT
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200 ulICCIARConst: .word ulICCIAR
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201 ulICCEOIRConst: .word ulICCEOIR
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207 PrefetchAbortHandler:
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