2 FreeRTOS V9.0.0 - Copyright (C) 2016 Real Time Engineers Ltd.
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5 VISIT http://www.FreeRTOS.org TO ENSURE YOU ARE USING THE LATEST VERSION.
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7 This file is part of the FreeRTOS distribution.
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9 FreeRTOS is free software; you can redistribute it and/or modify it under
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10 the terms of the GNU General Public License (version 2) as published by the
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11 Free Software Foundation >>>> AND MODIFIED BY <<<< the FreeRTOS exception.
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13 ***************************************************************************
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14 >>! NOTE: The modification to the GPL is included to allow you to !<<
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15 >>! distribute a combined work that includes FreeRTOS without being !<<
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16 >>! obliged to provide the source code for proprietary components !<<
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17 >>! outside of the FreeRTOS kernel. !<<
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18 ***************************************************************************
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20 FreeRTOS is distributed in the hope that it will be useful, but WITHOUT ANY
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21 WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
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22 FOR A PARTICULAR PURPOSE. Full license text is available on the following
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23 link: http://www.freertos.org/a00114.html
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25 ***************************************************************************
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27 * FreeRTOS provides completely free yet professionally developed, *
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28 * robust, strictly quality controlled, supported, and cross *
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29 * platform software that is more than just the market leader, it *
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30 * is the industry's de facto standard. *
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32 * Help yourself get started quickly while simultaneously helping *
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33 * to support the FreeRTOS project by purchasing a FreeRTOS *
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34 * tutorial book, reference manual, or both: *
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35 * http://www.FreeRTOS.org/Documentation *
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37 ***************************************************************************
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39 http://www.FreeRTOS.org/FAQHelp.html - Having a problem? Start by reading
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40 the FAQ page "My application does not run, what could be wrong?". Have you
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41 defined configASSERT()?
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43 http://www.FreeRTOS.org/support - In return for receiving this top quality
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44 embedded software for free we request you assist our global community by
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45 participating in the support forum.
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47 http://www.FreeRTOS.org/training - Investing in training allows your team to
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48 be as productive as possible as early as possible. Now you can receive
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49 FreeRTOS training directly from Richard Barry, CEO of Real Time Engineers
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50 Ltd, and the world's leading authority on the world's leading RTOS.
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52 http://www.FreeRTOS.org/plus - A selection of FreeRTOS ecosystem products,
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53 including FreeRTOS+Trace - an indispensable productivity tool, a DOS
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54 compatible FAT file system, and our tiny thread aware UDP/IP stack.
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56 http://www.FreeRTOS.org/labs - Where new FreeRTOS products go to incubate.
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57 Come and try FreeRTOS+TCP, our new open source TCP/IP stack for FreeRTOS.
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59 http://www.OpenRTOS.com - Real Time Engineers ltd. license FreeRTOS to High
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60 Integrity Systems ltd. to sell under the OpenRTOS brand. Low cost OpenRTOS
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61 licenses offer ticketed support, indemnification and commercial middleware.
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63 http://www.SafeRTOS.com - High Integrity Systems also provide a safety
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64 engineered and independently SIL3 certified version for use in safety and
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65 mission critical applications that require provable dependability.
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70 #include "FreeRTOSConfig.h"
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72 #define portCONTEXT_SIZE 132
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73 #define portEPC_STACK_LOCATION 124
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74 #define portSTATUS_STACK_LOCATION 128
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76 /******************************************************************/
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77 .macro portSAVE_CONTEXT
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79 /* Make room for the context. First save the current status so it can be
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80 manipulated, and the cause and EPC registers so their original values are
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83 addiu sp, sp, -portCONTEXT_SIZE
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84 mfc0 k1, _CP0_STATUS
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86 /* Also save s6 and s5 so they can be used. Any nesting interrupts should
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87 maintain the values of these registers across the ISR. */
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90 sw k1, portSTATUS_STACK_LOCATION(sp)
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92 /* Prepare to enable interrupts above the current priority. */
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97 /* s5 is used as the frame pointer. */
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100 /* Check the nesting count value. */
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101 la k0, uxInterruptNesting
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104 /* If the nesting count is 0 then swap to the the system stack, otherwise
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105 the system stack is already being used. */
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109 /* Swap to the system stack. */
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110 la sp, xISRStackTop
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113 /* Increment and save the nesting count. */
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117 /* s6 holds the EPC value, this is saved after interrupts are re-enabled. */
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120 /* Re-enable interrupts. */
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121 mtc0 k1, _CP0_STATUS
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123 /* Save the context into the space just created. s6 is saved again
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124 here as it now contains the EPC value. No other s registers need be
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144 sw s6, portEPC_STACK_LOCATION(s5)
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147 /* s6 is used as a scratch register. */
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153 /* Update the task stack pointer value if nesting is zero. */
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154 la s6, uxInterruptNesting
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160 /* Save the stack pointer. */
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161 la s6, uxSavedTaskStackPointer
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166 /******************************************************************/
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167 .macro portRESTORE_CONTEXT
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169 /* Restore the stack pointer from the TCB. This is only done if the
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170 nesting count is 1. */
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171 la s6, uxInterruptNesting
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176 la s6, uxSavedTaskStackPointer
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179 /* Restore the context. */
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185 /* s6 is loaded as it was used as a scratch register and therefore saved
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186 as part of the interrupt context. */
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207 /* Protect access to the k registers, and others. */
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211 /* Decrement the nesting count. */
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212 la k0, uxInterruptNesting
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217 lw k0, portSTATUS_STACK_LOCATION(s5)
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218 lw k1, portEPC_STACK_LOCATION(s5)
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220 /* Leave the stack in its original state. First load sp from s5, then
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221 restore s5 from the stack. */
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224 addiu sp, sp, portCONTEXT_SIZE
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226 mtc0 k0, _CP0_STATUS
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