2 FreeRTOS V7.4.2 - Copyright (C) 2013 Real Time Engineers Ltd.
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4 FEATURES AND PORTS ARE ADDED TO FREERTOS ALL THE TIME. PLEASE VISIT
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5 http://www.FreeRTOS.org TO ENSURE YOU ARE USING THE LATEST VERSION.
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7 ***************************************************************************
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9 * FreeRTOS tutorial books are available in pdf and paperback. *
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10 * Complete, revised, and edited pdf reference manuals are also *
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13 * Purchasing FreeRTOS documentation will not only help you, by *
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14 * ensuring you get running as quickly as possible and with an *
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15 * in-depth knowledge of how to use FreeRTOS, it will also help *
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16 * the FreeRTOS project to continue with its mission of providing *
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17 * professional grade, cross platform, de facto standard solutions *
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18 * for microcontrollers - completely free of charge! *
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20 * >>> See http://www.FreeRTOS.org/Documentation for details. <<< *
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22 * Thank you for using FreeRTOS, and thank you for your support! *
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24 ***************************************************************************
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27 This file is part of the FreeRTOS distribution.
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29 FreeRTOS is free software; you can redistribute it and/or modify it under
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30 the terms of the GNU General Public License (version 2) as published by the
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31 Free Software Foundation AND MODIFIED BY the FreeRTOS exception.
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33 >>>>>>NOTE<<<<<< The modification to the GPL is included to allow you to
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34 distribute a combined work that includes FreeRTOS without being obliged to
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35 provide the source code for proprietary components outside of the FreeRTOS
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38 FreeRTOS is distributed in the hope that it will be useful, but WITHOUT ANY
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39 WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
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40 FOR A PARTICULAR PURPOSE. See the GNU General Public License for more
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41 details. You should have received a copy of the GNU General Public License
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42 and the FreeRTOS license exception along with FreeRTOS; if not it can be
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43 viewed here: http://www.freertos.org/a00114.html and also obtained by
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44 writing to Real Time Engineers Ltd., contact details for whom are available
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45 on the FreeRTOS WEB site.
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49 ***************************************************************************
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51 * Having a problem? Start by reading the FAQ "My application does *
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52 * not run, what could be wrong?" *
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54 * http://www.FreeRTOS.org/FAQHelp.html *
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56 ***************************************************************************
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59 http://www.FreeRTOS.org - Documentation, books, training, latest versions,
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60 license and Real Time Engineers Ltd. contact details.
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62 http://www.FreeRTOS.org/plus - A selection of FreeRTOS ecosystem products,
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63 including FreeRTOS+Trace - an indispensable productivity tool, and our new
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64 fully thread aware and reentrant UDP/IP stack.
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66 http://www.OpenRTOS.com - Real Time Engineers ltd license FreeRTOS to High
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67 Integrity Systems, who sell the code with commercial support,
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68 indemnification and middleware, under the OpenRTOS brand.
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70 http://www.SafeRTOS.com - High Integrity Systems also provide a safety
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71 engineered and independently SIL3 certified version for use in safety and
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72 mission critical applications that require provable dependability.
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78 + pxPortInitialiseStack() now initialises the stack of new tasks to the
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79 same format used by the compiler. This allows the compiler generated
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80 interrupt mechanism to be used for context switches.
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82 Changes from V2.4.2:
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84 + pvPortMalloc and vPortFree have been removed. The projects now use
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85 the definitions from the source/portable/MemMang directory.
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87 Changes from V2.6.1:
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89 + usPortCheckFreeStackSpace() has been moved to tasks.c.
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95 #include "FreeRTOS.h"
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97 /*-----------------------------------------------------------*/
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99 /* See header file for description. */
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100 portSTACK_TYPE *pxPortInitialiseStack( portSTACK_TYPE *pxTopOfStack, pdTASK_CODE pxCode, void *pvParameters )
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102 portSTACK_TYPE DS_Reg = 0, *pxOriginalSP;
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104 /* Place a few bytes of known values on the bottom of the stack.
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105 This is just useful for debugging. */
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107 *pxTopOfStack = 0x1111;
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109 *pxTopOfStack = 0x2222;
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111 *pxTopOfStack = 0x3333;
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113 *pxTopOfStack = 0x4444;
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115 *pxTopOfStack = 0x5555;
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119 /*lint -e950 -e611 -e923 Lint doesn't like this much - but nothing I can do about it. */
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121 /* We are going to start the scheduler using a return from interrupt
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122 instruction to load the program counter, so first there would be the
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123 status register and interrupt return address. We make this the start
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125 *pxTopOfStack = portINITIAL_SW;
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127 *pxTopOfStack = FP_SEG( pxCode );
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129 *pxTopOfStack = FP_OFF( pxCode );
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132 /* We are going to setup the stack for the new task to look like
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133 the stack frame was setup by a compiler generated ISR. We need to know
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134 the address of the existing stack top to place in the SP register within
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135 the stack frame. pxOriginalSP holds SP before (simulated) pusha was
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137 pxOriginalSP = pxTopOfStack;
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139 /* The remaining registers would be pushed on the stack by our context
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140 switch function. These are loaded with values simply to make debugging
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142 *pxTopOfStack = FP_OFF( pvParameters ); /* AX */
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144 *pxTopOfStack = ( portSTACK_TYPE ) 0xCCCC; /* CX */
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146 *pxTopOfStack = FP_SEG( pvParameters ); /* DX */
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148 *pxTopOfStack = ( portSTACK_TYPE ) 0xBBBB; /* BX */
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150 *pxTopOfStack = FP_OFF( pxOriginalSP ); /* SP */
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152 *pxTopOfStack = ( portSTACK_TYPE ) 0xBBBB; /* BP */
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154 *pxTopOfStack = ( portSTACK_TYPE ) 0x0123; /* SI */
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156 *pxTopOfStack = ( portSTACK_TYPE ) 0xDDDD; /* DI */
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158 /* We need the true data segment. */
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159 __asm{ MOV DS_Reg, DS };
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162 *pxTopOfStack = DS_Reg; /* DS */
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165 *pxTopOfStack = ( portSTACK_TYPE ) 0xEEEE; /* ES */
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167 /* The AX register is pushed again twice - don't know why. */
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169 *pxTopOfStack = FP_OFF( pvParameters ); /* AX */
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171 *pxTopOfStack = FP_OFF( pvParameters ); /* AX */
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175 /* The compiler adds space to each ISR stack if building to
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176 include debug information. Presumably this is used by the
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177 debugger - we don't need to initialise it to anything just
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178 make sure it is there. */
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182 /*lint +e950 +e611 +e923 */
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184 return pxTopOfStack;
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186 /*-----------------------------------------------------------*/
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