2 FreeRTOS V8.1.2 - Copyright (C) 2014 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 ***************************************************************************
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9 * FreeRTOS provides completely free yet professionally developed, *
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10 * robust, strictly quality controlled, supported, and cross *
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11 * platform software that has become a de facto standard. *
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13 * Help yourself get started quickly and support the FreeRTOS *
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14 * project by purchasing a FreeRTOS tutorial book, reference *
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15 * manual, or both from: http://www.FreeRTOS.org/Documentation *
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19 ***************************************************************************
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21 This file is part of the FreeRTOS distribution.
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23 FreeRTOS is free software; you can redistribute it and/or modify it under
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24 the terms of the GNU General Public License (version 2) as published by the
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25 Free Software Foundation >>!AND MODIFIED BY!<< the FreeRTOS exception.
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27 >>! NOTE: The modification to the GPL is included to allow you to !<<
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28 >>! distribute a combined work that includes FreeRTOS without being !<<
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29 >>! obliged to provide the source code for proprietary components !<<
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30 >>! outside of the FreeRTOS kernel. !<<
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32 FreeRTOS is distributed in the hope that it will be useful, but WITHOUT ANY
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33 WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
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34 FOR A PARTICULAR PURPOSE. Full license text is available from the following
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35 link: http://www.freertos.org/a00114.html
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39 ***************************************************************************
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41 * Having a problem? Start by reading the FAQ "My application does *
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42 * not run, what could be wrong?" *
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44 * http://www.FreeRTOS.org/FAQHelp.html *
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46 ***************************************************************************
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48 http://www.FreeRTOS.org - Documentation, books, training, latest versions,
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49 license and Real Time Engineers Ltd. contact details.
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51 http://www.FreeRTOS.org/plus - A selection of FreeRTOS ecosystem products,
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52 including FreeRTOS+Trace - an indispensable productivity tool, a DOS
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53 compatible FAT file system, and our tiny thread aware UDP/IP stack.
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55 http://www.OpenRTOS.com - Real Time Engineers ltd license FreeRTOS to High
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56 Integrity Systems to sell under the OpenRTOS brand. Low cost OpenRTOS
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57 licenses offer ticketed support, indemnification and middleware.
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59 http://www.SafeRTOS.com - High Integrity Systems also provide a safety
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60 engineered and independently SIL3 certified version for use in safety and
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61 mission critical applications that require provable dependability.
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66 #include "FreeRTOSConfig.h"
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68 #define portCONTEXT_SIZE 132
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69 #define portEPC_STACK_LOCATION 124
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70 #define portSTATUS_STACK_LOCATION 128
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72 /******************************************************************/
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73 .macro portSAVE_CONTEXT
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75 /* Make room for the context. First save the current status so it can be
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76 manipulated, and the cause and EPC registers so their original values are
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79 addiu sp, sp, -portCONTEXT_SIZE
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80 mfc0 k1, _CP0_STATUS
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82 /* Also save s6 and s5 so they can be used. Any nesting interrupts should
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83 maintain the values of these registers across the ISR. */
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86 sw k1, portSTATUS_STACK_LOCATION(sp)
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88 /* Prepare to enable interrupts above the current priority. */
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93 /* s5 is used as the frame pointer. */
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96 /* Check the nesting count value. */
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97 la k0, uxInterruptNesting
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100 /* If the nesting count is 0 then swap to the the system stack, otherwise
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101 the system stack is already being used. */
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105 /* Swap to the system stack. */
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106 la sp, xISRStackTop
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109 /* Increment and save the nesting count. */
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113 /* s6 holds the EPC value, this is saved after interrupts are re-enabled. */
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116 /* Re-enable interrupts. */
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117 mtc0 k1, _CP0_STATUS
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119 /* Save the context into the space just created. s6 is saved again
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120 here as it now contains the EPC value. No other s registers need be
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140 sw s6, portEPC_STACK_LOCATION(s5)
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143 /* s6 is used as a scratch register. */
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149 /* Update the task stack pointer value if nesting is zero. */
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150 la s6, uxInterruptNesting
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156 /* Save the stack pointer. */
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157 la s6, uxSavedTaskStackPointer
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162 /******************************************************************/
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163 .macro portRESTORE_CONTEXT
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165 /* Restore the stack pointer from the TCB. This is only done if the
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166 nesting count is 1. */
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167 la s6, uxInterruptNesting
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172 la s6, uxSavedTaskStackPointer
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175 /* Restore the context. */
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181 /* s6 is loaded as it was used as a scratch register and therefore saved
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182 as part of the interrupt context. */
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203 /* Protect access to the k registers, and others. */
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207 /* Decrement the nesting count. */
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208 la k0, uxInterruptNesting
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213 lw k0, portSTATUS_STACK_LOCATION(s5)
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214 lw k1, portEPC_STACK_LOCATION(s5)
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216 /* Leave the stack in its original state. First load sp from s5, then
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217 restore s5 from the stack. */
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220 addiu sp, sp, portCONTEXT_SIZE
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222 mtc0 k0, _CP0_STATUS
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