2 FreeRTOS V7.2.0 - Copyright (C) 2012 Real Time Engineers Ltd.
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5 ***************************************************************************
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7 * FreeRTOS tutorial books are available in pdf and paperback. *
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8 * Complete, revised, and edited pdf reference manuals are also *
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11 * Purchasing FreeRTOS documentation will not only help you, by *
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12 * ensuring you get running as quickly as possible and with an *
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13 * in-depth knowledge of how to use FreeRTOS, it will also help *
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14 * the FreeRTOS project to continue with its mission of providing *
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15 * professional grade, cross platform, de facto standard solutions *
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16 * for microcontrollers - completely free of charge! *
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18 * >>> See http://www.FreeRTOS.org/Documentation for details. <<< *
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20 * Thank you for using FreeRTOS, and thank you for your support! *
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22 ***************************************************************************
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25 This file is part of the FreeRTOS distribution.
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27 FreeRTOS is free software; you can redistribute it and/or modify it under
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28 the terms of the GNU General Public License (version 2) as published by the
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29 Free Software Foundation AND MODIFIED BY the FreeRTOS exception.
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30 >>>NOTE<<< The modification to the GPL is included to allow you to
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31 distribute a combined work that includes FreeRTOS without being obliged to
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32 provide the source code for proprietary components outside of the FreeRTOS
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33 kernel. FreeRTOS is distributed in the hope that it will be useful, but
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34 WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
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35 or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
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36 more details. You should have received a copy of the GNU General Public
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37 License and the FreeRTOS license exception along with FreeRTOS; if not it
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38 can be viewed here: http://www.freertos.org/a00114.html and also obtained
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39 by writing to Richard Barry, contact details for whom are available on the
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44 ***************************************************************************
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46 * Having a problem? Start by reading the FAQ "My application does *
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47 * not run, what could be wrong? *
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49 * http://www.FreeRTOS.org/FAQHelp.html *
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51 ***************************************************************************
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54 http://www.FreeRTOS.org - Documentation, training, latest information,
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55 license and contact details.
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57 http://www.FreeRTOS.org/plus - A selection of FreeRTOS ecosystem products,
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58 including FreeRTOS+Trace - an indispensable productivity tool.
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60 Real Time Engineers ltd license FreeRTOS to High Integrity Systems, who sell
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61 the code with commercial support, indemnification, and middleware, under
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62 the OpenRTOS brand: http://www.OpenRTOS.com. High Integrity Systems also
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63 provide a safety engineered and independently SIL3 certified version under
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64 the SafeRTOS brand: http://www.SafeRTOS.com.
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67 #include "FreeRTOSConfig.h"
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69 #define portCONTEXT_SIZE 132
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70 #define portEPC_STACK_LOCATION 124
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71 #define portSTATUS_STACK_LOCATION 128
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73 /******************************************************************/
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74 .macro portSAVE_CONTEXT
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76 /* Make room for the context. First save the current status so we can
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77 manipulate it, and the cause and EPC registers so we capture their
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78 original values in case of interrupt nesting. */
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80 addiu sp, sp, -portCONTEXT_SIZE
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81 mfc0 k1, _CP0_STATUS
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83 /* Also save s6 and s5 so we can use them during this interrupt. Any
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84 nesting interrupts should maintain the values of these registers
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88 sw k1, portSTATUS_STACK_LOCATION(sp)
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90 /* Enable interrupts above the current priority. */
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95 /* s5 is used as the frame pointer. */
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98 /* Check the nesting count value. */
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99 la k0, uxInterruptNesting
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102 /* If the nesting count is 0 then swap to the the system stack, otherwise
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103 the system stack is already being used. */
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107 /* Swap to the system stack. */
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108 la sp, xISRStackTop
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111 /* Increment and save the nesting count. */
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115 /* s6 holds the EPC value, this is saved after interrupts are re-enabled. */
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118 /* Re-enable interrupts. */
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119 mtc0 k1, _CP0_STATUS
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121 /* Save the context into the space just created. s6 is saved again
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122 here as it now contains the EPC value. No other s registers need be
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142 sw s6, portEPC_STACK_LOCATION(s5)
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145 /* s6 is used as a scratch register. */
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151 /* Update the task stack pointer value if nesting is zero. */
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152 la s6, uxInterruptNesting
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158 /* Save the stack pointer. */
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159 la s6, uxSavedTaskStackPointer
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164 /******************************************************************/
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165 .macro portRESTORE_CONTEXT
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167 /* Restore the stack pointer from the TCB. This is only done if the
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168 nesting count is 1. */
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169 la s6, uxInterruptNesting
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174 la s6, uxSavedTaskStackPointer
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177 /* Restore the context. */
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183 /* s6 is loaded as it was used as a scratch register and therefore saved
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184 as part of the interrupt context. */
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205 /* Protect access to the k registers, and others. */
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208 /* Decrement the nesting count. */
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209 la k0, uxInterruptNesting
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214 lw k0, portSTATUS_STACK_LOCATION(s5)
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215 lw k1, portEPC_STACK_LOCATION(s5)
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217 /* Leave the stack how we found it. First load sp from s5, then restore
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218 s5 from the stack. */
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221 addiu sp, sp, portCONTEXT_SIZE
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223 mtc0 k0, _CP0_STATUS
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