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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75 /* Scheduler includes. */
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76 #include "FreeRTOS.h"
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80 #define portMAX_INTERRUPTS ( ( unsigned long ) sizeof( unsigned long ) * 8UL ) /* The number of bits in an unsigned long. */
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81 #define portNO_CRITICAL_NESTING ( ( unsigned long ) 0 )
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84 * Created as a high priority thread, this function uses a timer to simulate
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85 * a tick interrupt being generated on an embedded target. In this Windows
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86 * environment the timer does not achieve anything approaching real time
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87 * performance though.
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89 static DWORD WINAPI prvSimulatedPeripheralTimer( LPVOID lpParameter );
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92 * Process all the simulated interrupts - each represented by a bit in
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93 * ulPendingInterrupts variable.
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95 static void prvProcessSimulatedInterrupts( void );
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98 * Interrupt handlers used by the kernel itself. These are executed from the
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99 * simulated interrupt handler thread.
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101 static unsigned long prvProcessYieldInterrupt( void );
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102 static unsigned long prvProcessTickInterrupt( void );
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104 /*-----------------------------------------------------------*/
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106 /* The WIN32 simulator runs each task in a thread. The context switching is
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107 managed by the threads, so the task stack does not have to be managed directly,
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108 although the task stack is still used to hold an xThreadState structure this is
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109 the only thing it will ever hold. The structure indirectly maps the task handle
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110 to a thread handle. */
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113 /* Handle of the thread that executes the task. */
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118 /* Simulated interrupts waiting to be processed. This is a bit mask where each
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119 bit represents one interrupt, so a maximum of 32 interrupts can be simulated. */
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120 static volatile unsigned long ulPendingInterrupts = 0UL;
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122 /* An event used to inform the simulated interrupt processing thread (a high
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123 priority thread that simulated interrupt processing) that an interrupt is
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125 static void *pvInterruptEvent = NULL;
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127 /* Mutex used to protect all the simulated interrupt variables that are accessed
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128 by multiple threads. */
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129 static void *pvInterruptEventMutex = NULL;
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131 /* The critical nesting count for the currently executing task. This is
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132 initialised to a non-zero value so interrupts do not become enabled during
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133 the initialisation phase. As each task has its own critical nesting value
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134 ulCriticalNesting will get set to zero when the first task runs. This
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135 initialisation is probably not critical in this simulated environment as the
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136 simulated interrupt handlers do not get created until the FreeRTOS scheduler is
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138 static unsigned long ulCriticalNesting = 9999UL;
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140 /* Handlers for all the simulated software interrupts. The first two positions
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141 are used for the Yield and Tick interrupts so are handled slightly differently,
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142 all the other interrupts can be user defined. */
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143 static unsigned long (*ulIsrHandler[ portMAX_INTERRUPTS ])( void ) = { 0 };
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145 /* Pointer to the TCB of the currently executing task. */
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146 extern void *pxCurrentTCB;
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148 /*-----------------------------------------------------------*/
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150 static DWORD WINAPI prvSimulatedPeripheralTimer( LPVOID lpParameter )
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152 portTickType xMinimumWindowsBlockTime = ( portTickType ) 20;
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154 /* Just to prevent compiler warnings. */
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155 ( void ) lpParameter;
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159 /* Wait until the timer expires and we can access the simulated interrupt
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160 variables. *NOTE* this is not a 'real time' way of generating tick
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161 events as the next wake time should be relative to the previous wake
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162 time, not the time that Sleep() is called. It is done this way to
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163 prevent overruns in this very non real time simulated/emulated
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165 if( portTICK_RATE_MS < xMinimumWindowsBlockTime )
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167 Sleep( xMinimumWindowsBlockTime );
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171 Sleep( portTICK_RATE_MS );
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174 WaitForSingleObject( pvInterruptEventMutex, INFINITE );
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176 /* The timer has expired, generate the simulated tick event. */
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177 ulPendingInterrupts |= ( 1 << portINTERRUPT_TICK );
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179 /* The interrupt is now pending - notify the simulated interrupt
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181 SetEvent( pvInterruptEvent );
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183 /* Give back the mutex so the simulated interrupt handler unblocks
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184 and can access the interrupt handler variables. */
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185 ReleaseMutex( pvInterruptEventMutex );
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189 /* Should never reach here - MingW complains if you leave this line out,
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190 MSVC complains if you put it in. */
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194 /*-----------------------------------------------------------*/
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196 portSTACK_TYPE *pxPortInitialiseStack( portSTACK_TYPE *pxTopOfStack, pdTASK_CODE pxCode, void *pvParameters )
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198 xThreadState *pxThreadState = NULL;
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200 /* In this simulated case a stack is not initialised, but instead a thread
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201 is created that will execute the task being created. The thread handles
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202 the context switching itself. The xThreadState object is placed onto
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203 the stack that was created for the task - so the stack buffer is still
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204 used, just not in the conventional way. It will not be used for anything
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205 other than holding this structure. */
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206 pxThreadState = ( xThreadState * ) ( pxTopOfStack - sizeof( xThreadState ) );
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208 /* Create the thread itself. */
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209 pxThreadState->pvThread = CreateThread( NULL, 0, ( LPTHREAD_START_ROUTINE ) pxCode, pvParameters, CREATE_SUSPENDED, NULL );
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210 SetThreadAffinityMask( pxThreadState->pvThread, 0x01 );
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211 SetThreadPriorityBoost( pxThreadState->pvThread, TRUE );
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212 SetThreadPriority( pxThreadState->pvThread, THREAD_PRIORITY_IDLE );
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214 return ( portSTACK_TYPE * ) pxThreadState;
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216 /*-----------------------------------------------------------*/
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218 portBASE_TYPE xPortStartScheduler( void )
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221 long lSuccess = pdPASS;
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222 xThreadState *pxThreadState;
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224 /* Install the interrupt handlers used by the scheduler itself. */
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225 vPortSetInterruptHandler( portINTERRUPT_YIELD, prvProcessYieldInterrupt );
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226 vPortSetInterruptHandler( portINTERRUPT_TICK, prvProcessTickInterrupt );
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228 /* Create the events and mutexes that are used to synchronise all the
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230 pvInterruptEventMutex = CreateMutex( NULL, FALSE, NULL );
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231 pvInterruptEvent = CreateEvent( NULL, FALSE, FALSE, NULL );
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233 if( ( pvInterruptEventMutex == NULL ) || ( pvInterruptEvent == NULL ) )
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238 /* Set the priority of this thread such that it is above the priority of
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239 the threads that run tasks. This higher priority is required to ensure
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240 simulated interrupts take priority over tasks. */
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241 pvHandle = GetCurrentThread();
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242 if( pvHandle == NULL )
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247 if( lSuccess == pdPASS )
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249 if( SetThreadPriority( pvHandle, THREAD_PRIORITY_NORMAL ) == 0 )
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253 SetThreadPriorityBoost( pvHandle, TRUE );
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254 SetThreadAffinityMask( pvHandle, 0x01 );
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257 if( lSuccess == pdPASS )
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259 /* Start the thread that simulates the timer peripheral to generate
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260 tick interrupts. The priority is set below that of the simulated
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261 interrupt handler so the interrupt event mutex is used for the
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262 handshake / overrun protection. */
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263 pvHandle = CreateThread( NULL, 0, prvSimulatedPeripheralTimer, NULL, 0, NULL );
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264 if( pvHandle != NULL )
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266 SetThreadPriority( pvHandle, THREAD_PRIORITY_BELOW_NORMAL );
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267 SetThreadPriorityBoost( pvHandle, TRUE );
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268 SetThreadAffinityMask( pvHandle, 0x01 );
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271 /* Start the highest priority task by obtaining its associated thread
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272 state structure, in which is stored the thread handle. */
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273 pxThreadState = ( xThreadState * ) *( ( unsigned long * ) pxCurrentTCB );
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274 ulCriticalNesting = portNO_CRITICAL_NESTING;
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276 /* Bump up the priority of the thread that is going to run, in the
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277 hope that this will asist in getting the Windows thread scheduler to
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278 behave as an embedded engineer might expect. */
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279 ResumeThread( pxThreadState->pvThread );
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281 /* Handle all simulated interrupts - including yield requests and
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282 simulated ticks. */
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283 prvProcessSimulatedInterrupts();
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286 /* Would not expect to return from prvProcessSimulatedInterrupts(), so should
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290 /*-----------------------------------------------------------*/
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292 static unsigned long prvProcessYieldInterrupt( void )
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296 /*-----------------------------------------------------------*/
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298 static unsigned long prvProcessTickInterrupt( void )
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300 unsigned long ulSwitchRequired;
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302 /* Process the tick itself. */
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303 vTaskIncrementTick();
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304 #if( configUSE_PREEMPTION != 0 )
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306 /* A context switch is only automatically performed from the tick
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307 interrupt if the pre-emptive scheduler is being used. */
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308 ulSwitchRequired = pdTRUE;
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312 ulSwitchRequired = pdFALSE;
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316 return ulSwitchRequired;
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318 /*-----------------------------------------------------------*/
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320 static void prvProcessSimulatedInterrupts( void )
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322 unsigned long ulSwitchRequired, i;
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323 xThreadState *pxThreadState;
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324 void *pvObjectList[ 2 ];
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326 /* Going to block on the mutex that ensured exclusive access to the simulated
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327 interrupt objects, and the event that signals that a simulated interrupt
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328 should be processed. */
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329 pvObjectList[ 0 ] = pvInterruptEventMutex;
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330 pvObjectList[ 1 ] = pvInterruptEvent;
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334 WaitForMultipleObjects( sizeof( pvObjectList ) / sizeof( void * ), pvObjectList, TRUE, INFINITE );
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336 /* Used to indicate whether the simulated interrupt processing has
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337 necessitated a context switch to another task/thread. */
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338 ulSwitchRequired = pdFALSE;
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340 /* For each interrupt we are interested in processing, each of which is
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341 represented by a bit in the 32bit ulPendingInterrupts variable. */
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342 for( i = 0; i < portMAX_INTERRUPTS; i++ )
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344 /* Is the simulated interrupt pending? */
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345 if( ulPendingInterrupts & ( 1UL << i ) )
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347 /* Is a handler installed? */
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348 if( ulIsrHandler[ i ] != NULL )
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350 /* Run the actual handler. */
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351 if( ulIsrHandler[ i ]() != pdFALSE )
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353 ulSwitchRequired |= ( 1 << i );
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357 /* Clear the interrupt pending bit. */
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358 ulPendingInterrupts &= ~( 1UL << i );
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362 if( ulSwitchRequired != pdFALSE )
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364 void *pvOldCurrentTCB;
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366 pvOldCurrentTCB = pxCurrentTCB;
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368 /* Select the next task to run. */
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369 vTaskSwitchContext();
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371 /* If the task selected to enter the running state is not the task
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372 that is already in the running state. */
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373 if( pvOldCurrentTCB != pxCurrentTCB )
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375 /* Suspend the old thread. */
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376 pxThreadState = ( xThreadState *) *( ( unsigned long * ) pvOldCurrentTCB );
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377 SuspendThread( pxThreadState->pvThread );
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379 /* Obtain the state of the task now selected to enter the
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381 pxThreadState = ( xThreadState * ) ( *( unsigned long *) pxCurrentTCB );
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382 ResumeThread( pxThreadState->pvThread );
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386 ReleaseMutex( pvInterruptEventMutex );
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389 /*-----------------------------------------------------------*/
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391 void vPortDeleteThread( void *pvTaskToDelete )
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393 xThreadState *pxThreadState;
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395 WaitForSingleObject( pvInterruptEventMutex, INFINITE );
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397 /* Find the handle of the thread being deleted. */
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398 pxThreadState = ( xThreadState * ) ( *( unsigned long *) pvTaskToDelete );
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399 TerminateThread( pxThreadState->pvThread, 0 );
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401 ReleaseMutex( pvInterruptEventMutex );
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403 /*-----------------------------------------------------------*/
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405 void vPortEndScheduler( void )
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407 /* This function IS NOT TESTED! */
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408 TerminateProcess( GetCurrentProcess(), 0 );
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410 /*-----------------------------------------------------------*/
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412 void vPortGenerateSimulatedInterrupt( unsigned long ulInterruptNumber )
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414 xThreadState *pxThreadState;
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416 if( ( ulInterruptNumber < portMAX_INTERRUPTS ) && ( pvInterruptEventMutex != NULL ) )
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418 /* Yield interrupts are processed even when critical nesting is non-zero. */
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419 WaitForSingleObject( pvInterruptEventMutex, INFINITE );
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420 ulPendingInterrupts |= ( 1 << ulInterruptNumber );
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422 /* The simulated interrupt is now held pending, but don't actually process it
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423 yet if this call is within a critical section. It is possible for this to
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424 be in a critical section as calls to wait for mutexes are accumulative. */
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425 if( ulCriticalNesting == 0 )
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427 /* The event handler needs to know to signal the interrupt acknowledge event
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428 the next time this task runs. */
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429 pxThreadState = ( xThreadState * ) *( ( unsigned long * ) pxCurrentTCB );
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430 SetEvent( pvInterruptEvent );
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433 ReleaseMutex( pvInterruptEventMutex );
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436 /*-----------------------------------------------------------*/
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438 void vPortSetInterruptHandler( unsigned long ulInterruptNumber, unsigned long (*pvHandler)( void ) )
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440 if( ulInterruptNumber < portMAX_INTERRUPTS )
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442 if( pvInterruptEventMutex != NULL )
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444 WaitForSingleObject( pvInterruptEventMutex, INFINITE );
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445 ulIsrHandler[ ulInterruptNumber ] = pvHandler;
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446 ReleaseMutex( pvInterruptEventMutex );
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450 ulIsrHandler[ ulInterruptNumber ] = pvHandler;
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454 /*-----------------------------------------------------------*/
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456 void vPortEnterCritical( void )
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458 if( xTaskGetSchedulerState() != taskSCHEDULER_NOT_STARTED )
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460 /* The interrupt event mutex is held for the entire critical section,
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461 effectively disabling (simulated) interrupts. */
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462 WaitForSingleObject( pvInterruptEventMutex, INFINITE );
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463 ulCriticalNesting++;
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467 ulCriticalNesting++;
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470 /*-----------------------------------------------------------*/
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472 void vPortExitCritical( void )
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474 xThreadState *pxThreadState;
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475 long lMutexNeedsReleasing;
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477 /* The interrupt event mutex should already be held by this thread as it was
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478 obtained on entry to the critical section. */
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480 lMutexNeedsReleasing = pdTRUE;
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482 if( ulCriticalNesting > portNO_CRITICAL_NESTING )
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484 if( ulCriticalNesting == ( portNO_CRITICAL_NESTING + 1 ) )
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486 ulCriticalNesting--;
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488 /* Were any interrupts set to pending while interrupts were
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489 (simulated) disabled? */
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490 if( ulPendingInterrupts != 0UL )
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492 SetEvent( pvInterruptEvent );
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494 /* The event handler needs to know to signal the interrupt
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495 acknowledge event the next time this task runs. */
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496 pxThreadState = ( xThreadState * ) *( ( unsigned long * ) pxCurrentTCB );
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498 /* Mutex will be released now, so does not require releasing
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499 on function exit. */
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500 lMutexNeedsReleasing = pdFALSE;
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501 ReleaseMutex( pvInterruptEventMutex );
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506 /* Tick interrupts will still not be processed as the critical
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507 nesting depth will not be zero. */
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508 ulCriticalNesting--;
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512 if( lMutexNeedsReleasing == pdTRUE )
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514 ReleaseMutex( pvInterruptEventMutex );
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517 /*-----------------------------------------------------------*/
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