2 FreeRTOS V7.5.1 - Copyright (C) 2013 Real Time Engineers Ltd.
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4 VISIT http://www.FreeRTOS.org TO ENSURE YOU ARE USING THE LATEST VERSION.
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6 ***************************************************************************
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8 * FreeRTOS provides completely free yet professionally developed, *
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9 * robust, strictly quality controlled, supported, and cross *
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10 * platform software that has become a de facto standard. *
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12 * Help yourself get started quickly and support the FreeRTOS *
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13 * project by purchasing a FreeRTOS tutorial book, reference *
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14 * manual, or both from: http://www.FreeRTOS.org/Documentation *
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18 ***************************************************************************
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20 This file is part of the FreeRTOS distribution.
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22 FreeRTOS is free software; you can redistribute it and/or modify it under
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23 the terms of the GNU General Public License (version 2) as published by the
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24 Free Software Foundation >>!AND MODIFIED BY!<< the FreeRTOS exception.
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26 >>! NOTE: The modification to the GPL is included to allow you to distribute
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27 >>! a combined work that includes FreeRTOS without being obliged to provide
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28 >>! the source code for proprietary components outside of the FreeRTOS
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31 FreeRTOS is distributed in the hope that it will be useful, but WITHOUT ANY
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32 WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
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33 FOR A PARTICULAR PURPOSE. Full license text is available from the following
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34 link: http://www.freertos.org/a00114.html
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38 ***************************************************************************
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40 * Having a problem? Start by reading the FAQ "My application does *
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41 * not run, what could be wrong?" *
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43 * http://www.FreeRTOS.org/FAQHelp.html *
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45 ***************************************************************************
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47 http://www.FreeRTOS.org - Documentation, books, training, latest versions,
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48 license and Real Time Engineers Ltd. contact details.
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50 http://www.FreeRTOS.org/plus - A selection of FreeRTOS ecosystem products,
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51 including FreeRTOS+Trace - an indispensable productivity tool, a DOS
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52 compatible FAT file system, and our tiny thread aware UDP/IP stack.
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54 http://www.OpenRTOS.com - Real Time Engineers ltd license FreeRTOS to High
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55 Integrity Systems to sell under the OpenRTOS brand. Low cost OpenRTOS
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56 licenses offer ticketed support, indemnification and middleware.
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58 http://www.SafeRTOS.com - High Integrity Systems also provide a safety
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59 engineered and independently SIL3 certified version for use in safety and
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60 mission critical applications that require provable dependability.
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65 /* Scheduler includes. */
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66 #include "FreeRTOS.h"
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70 #define portMAX_INTERRUPTS ( ( unsigned long ) sizeof( unsigned long ) * 8UL ) /* The number of bits in an unsigned long. */
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71 #define portNO_CRITICAL_NESTING ( ( unsigned long ) 0 )
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74 * Created as a high priority thread, this function uses a timer to simulate
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75 * a tick interrupt being generated on an embedded target. In this Windows
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76 * environment the timer does not achieve anything approaching real time
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77 * performance though.
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79 static DWORD WINAPI prvSimulatedPeripheralTimer( LPVOID lpParameter );
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82 * Process all the simulated interrupts - each represented by a bit in
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83 * ulPendingInterrupts variable.
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85 static void prvProcessSimulatedInterrupts( void );
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88 * Interrupt handlers used by the kernel itself. These are executed from the
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89 * simulated interrupt handler thread.
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91 static unsigned long prvProcessYieldInterrupt( void );
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92 static unsigned long prvProcessTickInterrupt( void );
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94 /*-----------------------------------------------------------*/
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96 /* The WIN32 simulator runs each task in a thread. The context switching is
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97 managed by the threads, so the task stack does not have to be managed directly,
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98 although the task stack is still used to hold an xThreadState structure this is
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99 the only thing it will ever hold. The structure indirectly maps the task handle
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100 to a thread handle. */
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103 /* Handle of the thread that executes the task. */
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108 /* Simulated interrupts waiting to be processed. This is a bit mask where each
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109 bit represents one interrupt, so a maximum of 32 interrupts can be simulated. */
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110 static volatile unsigned long ulPendingInterrupts = 0UL;
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112 /* An event used to inform the simulated interrupt processing thread (a high
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113 priority thread that simulated interrupt processing) that an interrupt is
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115 static void *pvInterruptEvent = NULL;
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117 /* Mutex used to protect all the simulated interrupt variables that are accessed
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118 by multiple threads. */
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119 static void *pvInterruptEventMutex = NULL;
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121 /* The critical nesting count for the currently executing task. This is
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122 initialised to a non-zero value so interrupts do not become enabled during
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123 the initialisation phase. As each task has its own critical nesting value
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124 ulCriticalNesting will get set to zero when the first task runs. This
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125 initialisation is probably not critical in this simulated environment as the
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126 simulated interrupt handlers do not get created until the FreeRTOS scheduler is
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128 static unsigned long ulCriticalNesting = 9999UL;
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130 /* Handlers for all the simulated software interrupts. The first two positions
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131 are used for the Yield and Tick interrupts so are handled slightly differently,
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132 all the other interrupts can be user defined. */
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133 static unsigned long (*ulIsrHandler[ portMAX_INTERRUPTS ])( void ) = { 0 };
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135 /* Pointer to the TCB of the currently executing task. */
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136 extern void *pxCurrentTCB;
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138 /*-----------------------------------------------------------*/
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140 static DWORD WINAPI prvSimulatedPeripheralTimer( LPVOID lpParameter )
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142 portTickType xMinimumWindowsBlockTime = ( portTickType ) 20;
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144 /* Just to prevent compiler warnings. */
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145 ( void ) lpParameter;
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149 /* Wait until the timer expires and we can access the simulated interrupt
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150 variables. *NOTE* this is not a 'real time' way of generating tick
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151 events as the next wake time should be relative to the previous wake
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152 time, not the time that Sleep() is called. It is done this way to
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153 prevent overruns in this very non real time simulated/emulated
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155 if( portTICK_RATE_MS < xMinimumWindowsBlockTime )
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157 Sleep( xMinimumWindowsBlockTime );
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161 Sleep( portTICK_RATE_MS );
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164 WaitForSingleObject( pvInterruptEventMutex, INFINITE );
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166 /* The timer has expired, generate the simulated tick event. */
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167 ulPendingInterrupts |= ( 1 << portINTERRUPT_TICK );
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169 /* The interrupt is now pending - notify the simulated interrupt
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171 SetEvent( pvInterruptEvent );
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173 /* Give back the mutex so the simulated interrupt handler unblocks
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174 and can access the interrupt handler variables. */
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175 ReleaseMutex( pvInterruptEventMutex );
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179 /* Should never reach here - MingW complains if you leave this line out,
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180 MSVC complains if you put it in. */
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184 /*-----------------------------------------------------------*/
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186 portSTACK_TYPE *pxPortInitialiseStack( portSTACK_TYPE *pxTopOfStack, pdTASK_CODE pxCode, void *pvParameters )
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188 xThreadState *pxThreadState = NULL;
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189 char *pcTopOfStack = ( char * ) pxTopOfStack;
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191 /* In this simulated case a stack is not initialised, but instead a thread
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192 is created that will execute the task being created. The thread handles
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193 the context switching itself. The xThreadState object is placed onto
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194 the stack that was created for the task - so the stack buffer is still
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195 used, just not in the conventional way. It will not be used for anything
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196 other than holding this structure. */
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197 pxThreadState = ( xThreadState * ) ( pcTopOfStack - sizeof( xThreadState ) );
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199 /* Create the thread itself. */
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200 pxThreadState->pvThread = CreateThread( NULL, 0, ( LPTHREAD_START_ROUTINE ) pxCode, pvParameters, CREATE_SUSPENDED, NULL );
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201 SetThreadAffinityMask( pxThreadState->pvThread, 0x01 );
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202 SetThreadPriorityBoost( pxThreadState->pvThread, TRUE );
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203 SetThreadPriority( pxThreadState->pvThread, THREAD_PRIORITY_IDLE );
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205 return ( portSTACK_TYPE * ) pxThreadState;
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207 /*-----------------------------------------------------------*/
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209 portBASE_TYPE xPortStartScheduler( void )
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212 long lSuccess = pdPASS;
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213 xThreadState *pxThreadState;
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215 /* Install the interrupt handlers used by the scheduler itself. */
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216 vPortSetInterruptHandler( portINTERRUPT_YIELD, prvProcessYieldInterrupt );
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217 vPortSetInterruptHandler( portINTERRUPT_TICK, prvProcessTickInterrupt );
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219 /* Create the events and mutexes that are used to synchronise all the
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221 pvInterruptEventMutex = CreateMutex( NULL, FALSE, NULL );
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222 pvInterruptEvent = CreateEvent( NULL, FALSE, FALSE, NULL );
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224 if( ( pvInterruptEventMutex == NULL ) || ( pvInterruptEvent == NULL ) )
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229 /* Set the priority of this thread such that it is above the priority of
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230 the threads that run tasks. This higher priority is required to ensure
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231 simulated interrupts take priority over tasks. */
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232 pvHandle = GetCurrentThread();
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233 if( pvHandle == NULL )
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238 if( lSuccess == pdPASS )
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240 if( SetThreadPriority( pvHandle, THREAD_PRIORITY_NORMAL ) == 0 )
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244 SetThreadPriorityBoost( pvHandle, TRUE );
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245 SetThreadAffinityMask( pvHandle, 0x01 );
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248 if( lSuccess == pdPASS )
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250 /* Start the thread that simulates the timer peripheral to generate
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251 tick interrupts. The priority is set below that of the simulated
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252 interrupt handler so the interrupt event mutex is used for the
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253 handshake / overrun protection. */
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254 pvHandle = CreateThread( NULL, 0, prvSimulatedPeripheralTimer, NULL, 0, NULL );
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255 if( pvHandle != NULL )
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257 SetThreadPriority( pvHandle, THREAD_PRIORITY_BELOW_NORMAL );
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258 SetThreadPriorityBoost( pvHandle, TRUE );
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259 SetThreadAffinityMask( pvHandle, 0x01 );
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262 /* Start the highest priority task by obtaining its associated thread
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263 state structure, in which is stored the thread handle. */
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264 pxThreadState = ( xThreadState * ) *( ( unsigned long * ) pxCurrentTCB );
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265 ulCriticalNesting = portNO_CRITICAL_NESTING;
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267 /* Bump up the priority of the thread that is going to run, in the
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268 hope that this will asist in getting the Windows thread scheduler to
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269 behave as an embedded engineer might expect. */
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270 ResumeThread( pxThreadState->pvThread );
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272 /* Handle all simulated interrupts - including yield requests and
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273 simulated ticks. */
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274 prvProcessSimulatedInterrupts();
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277 /* Would not expect to return from prvProcessSimulatedInterrupts(), so should
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281 /*-----------------------------------------------------------*/
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283 static unsigned long prvProcessYieldInterrupt( void )
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287 /*-----------------------------------------------------------*/
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289 static unsigned long prvProcessTickInterrupt( void )
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291 unsigned long ulSwitchRequired;
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293 /* Process the tick itself. */
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294 ulSwitchRequired = ( unsigned long ) xTaskIncrementTick();
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296 return ulSwitchRequired;
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298 /*-----------------------------------------------------------*/
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300 static void prvProcessSimulatedInterrupts( void )
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302 unsigned long ulSwitchRequired, i;
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303 xThreadState *pxThreadState;
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304 void *pvObjectList[ 2 ];
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306 /* Going to block on the mutex that ensured exclusive access to the simulated
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307 interrupt objects, and the event that signals that a simulated interrupt
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308 should be processed. */
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309 pvObjectList[ 0 ] = pvInterruptEventMutex;
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310 pvObjectList[ 1 ] = pvInterruptEvent;
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314 WaitForMultipleObjects( sizeof( pvObjectList ) / sizeof( void * ), pvObjectList, TRUE, INFINITE );
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316 /* Used to indicate whether the simulated interrupt processing has
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317 necessitated a context switch to another task/thread. */
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318 ulSwitchRequired = pdFALSE;
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320 /* For each interrupt we are interested in processing, each of which is
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321 represented by a bit in the 32bit ulPendingInterrupts variable. */
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322 for( i = 0; i < portMAX_INTERRUPTS; i++ )
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324 /* Is the simulated interrupt pending? */
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325 if( ulPendingInterrupts & ( 1UL << i ) )
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327 /* Is a handler installed? */
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328 if( ulIsrHandler[ i ] != NULL )
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330 /* Run the actual handler. */
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331 if( ulIsrHandler[ i ]() != pdFALSE )
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333 ulSwitchRequired |= ( 1 << i );
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337 /* Clear the interrupt pending bit. */
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338 ulPendingInterrupts &= ~( 1UL << i );
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342 if( ulSwitchRequired != pdFALSE )
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344 void *pvOldCurrentTCB;
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346 pvOldCurrentTCB = pxCurrentTCB;
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348 /* Select the next task to run. */
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349 vTaskSwitchContext();
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351 /* If the task selected to enter the running state is not the task
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352 that is already in the running state. */
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353 if( pvOldCurrentTCB != pxCurrentTCB )
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355 /* Suspend the old thread. */
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356 pxThreadState = ( xThreadState *) *( ( unsigned long * ) pvOldCurrentTCB );
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357 SuspendThread( pxThreadState->pvThread );
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359 /* Obtain the state of the task now selected to enter the
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361 pxThreadState = ( xThreadState * ) ( *( unsigned long *) pxCurrentTCB );
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362 ResumeThread( pxThreadState->pvThread );
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366 ReleaseMutex( pvInterruptEventMutex );
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369 /*-----------------------------------------------------------*/
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371 void vPortDeleteThread( void *pvTaskToDelete )
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373 xThreadState *pxThreadState;
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375 WaitForSingleObject( pvInterruptEventMutex, INFINITE );
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377 /* Find the handle of the thread being deleted. */
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378 pxThreadState = ( xThreadState * ) ( *( unsigned long *) pvTaskToDelete );
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379 TerminateThread( pxThreadState->pvThread, 0 );
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381 ReleaseMutex( pvInterruptEventMutex );
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383 /*-----------------------------------------------------------*/
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385 void vPortEndScheduler( void )
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387 /* This function IS NOT TESTED! */
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388 TerminateProcess( GetCurrentProcess(), 0 );
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390 /*-----------------------------------------------------------*/
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392 void vPortGenerateSimulatedInterrupt( unsigned long ulInterruptNumber )
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394 if( ( ulInterruptNumber < portMAX_INTERRUPTS ) && ( pvInterruptEventMutex != NULL ) )
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396 /* Yield interrupts are processed even when critical nesting is non-zero. */
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397 WaitForSingleObject( pvInterruptEventMutex, INFINITE );
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398 ulPendingInterrupts |= ( 1 << ulInterruptNumber );
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400 /* The simulated interrupt is now held pending, but don't actually process it
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401 yet if this call is within a critical section. It is possible for this to
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402 be in a critical section as calls to wait for mutexes are accumulative. */
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403 if( ulCriticalNesting == 0 )
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405 SetEvent( pvInterruptEvent );
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408 ReleaseMutex( pvInterruptEventMutex );
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411 /*-----------------------------------------------------------*/
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413 void vPortSetInterruptHandler( unsigned long ulInterruptNumber, unsigned long (*pvHandler)( void ) )
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415 if( ulInterruptNumber < portMAX_INTERRUPTS )
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417 if( pvInterruptEventMutex != NULL )
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419 WaitForSingleObject( pvInterruptEventMutex, INFINITE );
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420 ulIsrHandler[ ulInterruptNumber ] = pvHandler;
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421 ReleaseMutex( pvInterruptEventMutex );
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425 ulIsrHandler[ ulInterruptNumber ] = pvHandler;
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429 /*-----------------------------------------------------------*/
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431 void vPortEnterCritical( void )
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433 if( xTaskGetSchedulerState() != taskSCHEDULER_NOT_STARTED )
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435 /* The interrupt event mutex is held for the entire critical section,
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436 effectively disabling (simulated) interrupts. */
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437 WaitForSingleObject( pvInterruptEventMutex, INFINITE );
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438 ulCriticalNesting++;
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442 ulCriticalNesting++;
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445 /*-----------------------------------------------------------*/
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447 void vPortExitCritical( void )
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449 long lMutexNeedsReleasing;
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451 /* The interrupt event mutex should already be held by this thread as it was
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452 obtained on entry to the critical section. */
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454 lMutexNeedsReleasing = pdTRUE;
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456 if( ulCriticalNesting > portNO_CRITICAL_NESTING )
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458 if( ulCriticalNesting == ( portNO_CRITICAL_NESTING + 1 ) )
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460 ulCriticalNesting--;
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462 /* Were any interrupts set to pending while interrupts were
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463 (simulated) disabled? */
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464 if( ulPendingInterrupts != 0UL )
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466 SetEvent( pvInterruptEvent );
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468 /* Mutex will be released now, so does not require releasing
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469 on function exit. */
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470 lMutexNeedsReleasing = pdFALSE;
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471 ReleaseMutex( pvInterruptEventMutex );
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476 /* Tick interrupts will still not be processed as the critical
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477 nesting depth will not be zero. */
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478 ulCriticalNesting--;
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482 if( lMutexNeedsReleasing == pdTRUE )
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484 ReleaseMutex( pvInterruptEventMutex );
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487 /*-----------------------------------------------------------*/
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