git.sur5r.net Git - freertos/blob - Source/portable/MSVC-MingW/port.c

   1 /*\r
   2     FreeRTOS V6.1.0 - Copyright (C) 2010 Real Time Engineers Ltd.\r
   3 \r
   4     ***************************************************************************\r
   5     *                                                                         *\r
   6     * If you are:                                                             *\r
   7     *                                                                         *\r
   8     *    + New to FreeRTOS,                                                   *\r
   9     *    + Wanting to learn FreeRTOS or multitasking in general quickly       *\r
  10     *    + Looking for basic training,                                        *\r
  11     *    + Wanting to improve your FreeRTOS skills and productivity           *\r
  12     *                                                                         *\r
  13     * then take a look at the FreeRTOS books - available as PDF or paperback  *\r
  14     *                                                                         *\r
  15     *        "Using the FreeRTOS Real Time Kernel - a Practical Guide"        *\r
  16     *                  http://www.FreeRTOS.org/Documentation                  *\r
  17     *                                                                         *\r
  18     * A pdf reference manual is also available.  Both are usually delivered   *\r
  19     * to your inbox within 20 minutes to two hours when purchased between 8am *\r
  20     * and 8pm GMT (although please allow up to 24 hours in case of            *\r
  21     * exceptional circumstances).  Thank you for your support!                *\r
  22     *                                                                         *\r
  23     ***************************************************************************\r
  24 \r
  25     This file is part of the FreeRTOS distribution.\r
  26 \r
  27     FreeRTOS is free software; you can redistribute it and/or modify it under\r
  28     the terms of the GNU General Public License (version 2) as published by the\r
  29     Free Software Foundation AND MODIFIED BY the FreeRTOS exception.\r
  30     ***NOTE*** The exception to the GPL is included to allow you to distribute\r
  31     a combined work that includes FreeRTOS without being obliged to provide the\r
  32     source code for proprietary components outside of the FreeRTOS kernel.\r
  33     FreeRTOS is distributed in the hope that it will be useful, but WITHOUT\r
  34     ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or\r
  35     FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for\r
  36     more details. You should have received a copy of the GNU General Public\r
  37     License and the FreeRTOS license exception along with FreeRTOS; if not it\r
  38     can be viewed here: http://www.freertos.org/a00114.html and also obtained\r
  39     by writing to Richard Barry, contact details for whom are available on the\r
  40     FreeRTOS WEB site.\r
  41 \r
  42     1 tab == 4 spaces!\r
  43 \r
  44     http://www.FreeRTOS.org - Documentation, latest information, license and\r
  45     contact details.\r
  46 \r
  47     http://www.SafeRTOS.com - A version that is certified for use in safety\r
  48     critical systems.\r
  49 \r
  50     http://www.OpenRTOS.com - Commercial support, development, porting,\r
  51     licensing and training services.\r
  52 */\r
  53 \r
  54 /* Scheduler includes. */\r
  55 #include "FreeRTOS.h"\r
  56 #include "task.h"\r
  57 #include <stdio.h>\r
  58 \r
  59 //FILE *pfTraceFile = NULL;\r
  60 //#define vPortTrace( x ) if( pfTraceFile == NULL ) pfTraceFile = fopen( "c:/temp/trace.txt", "w" ); if( pfTraceFile != NULL ) fprintf( pfTraceFile, x )\r
  61 #define vPortTrace( x ) ( void ) x\r
  62 \r
  63 #define portMAX_INTERRUPTS                              ( ( unsigned long ) sizeof( unsigned long ) * 8UL ) /* The number of bits in an unsigned long. */\r
  64 #define portNO_CRITICAL_NESTING                 ( ( unsigned long ) 0 )\r
  65 \r
  66 /*\r
  67  * Created as a high priority thread, this function uses a timer to simulate\r
  68  * a tick interrupt being generated on an embedded target.  In this Windows\r
  69  * environment the timer does not achieve real time performance though.\r
  70  */\r
  71 static DWORD WINAPI prvSimulatedPeripheralTimer( LPVOID lpParameter );\r
  72 \r
  73 /* \r
  74  * Process all the simulated interrupts - each represented by a bit in \r
  75  * ulPendingInterrupts variable.\r
  76  */\r
  77 static void prvProcessEvents( void );\r
  78 \r
  79 /*-----------------------------------------------------------*/\r
  80 \r
  81 /* The WIN32 simulator runs each task in a thread.  The context switching is\r
  82 managed by the threads, so the task stack does not have to be managed directly,\r
  83 although the task stack is still used to hold an xThreadState structure this is\r
  84 the only thing it will ever hold.  The structure indirectly maps the task handle \r
  85 to a thread handle. */\r
  86 typedef struct\r
  87 {\r
  88         /* Set to true for tasks that call the generate psuedo interrupt function,\r
  89         as the event handler needs to know whether to signal the interrupt ack\r
  90         event when the task next runs. */\r
  91         long lWaitingInterruptAck;                      \r
  92 \r
  93         /* Critical nesting count of the task - each task has its own. */\r
  94         portSTACK_TYPE ulCriticalNesting;\r
  95 \r
  96         /* Handle of the thread that executes the task. */\r
  97         void * pvThread;                                        \r
  98 } xThreadState;\r
  99 \r
 100 /* Pseudo interrupts waiting to be processed.  This is a bit mask where each\r
 101 bit represents one interrupt, so a maximum of 32 interrupts can be simulated. */\r
 102 static volatile unsigned long ulPendingInterrupts = 0UL;\r
 103 \r
 104 /* An event used to inform the interrupt dispatch thread (a high priority thread\r
 105 that simulated interrupt processing) that an IRQ or SWI type interrupt is\r
 106 pending. */\r
 107 static void *pvInterruptEvent = NULL;\r
 108 \r
 109 /* Mutex used to protect all the pseudo interrupt variables that are accessed by\r
 110 multiple threads. */\r
 111 static void *pvInterruptEventMutex = NULL;\r
 112 \r
 113 /* The main thread, which also acts as the pseudo interrupt handler. */\r
 114 static void *pvMainThreadAndInterrupHandler;\r
 115 \r
 116 /* Events used to manage sequencing. */\r
 117 static void *pvTickAcknowledgeEvent = NULL, *pvInterruptAcknowledgeEvent = NULL;\r
 118 \r
 119 /* The critical nesting count for the currently executing task.  This is \r
 120 initialised to a non-zero value so interrupts do not become enabled during \r
 121 the initialisation phase.  As each task has its own critical nesting value \r
 122 ulCriticalNesting will get set to zero when the first task runs.  This \r
 123 initialisation is probably not critical in this simulated environment as the\r
 124 pseudo interrupt handlers/dispatchers do not get created until the FreeRTOS\r
 125 scheduler is started. */\r
 126 static unsigned portLONG ulCriticalNesting = 9999UL;\r
 127 \r
 128 /* Handlers for all the simulated software interrupts.  The first two positions\r
 129 are used for the Yield and Tick interrupts so are handled slightly differently,\r
 130 all the other interrupts can be user defined. */\r
 131 static void (*vIsrHandler[ portMAX_INTERRUPTS ])( void ) = { 0 };\r
 132 \r
 133 /* Pointer to the TCB of the currently executing task. */\r
 134 extern void *pxCurrentTCB;\r
 135 \r
 136 /*-----------------------------------------------------------*/\r
 137 \r
 138 static DWORD WINAPI prvSimulatedPeripheralTimer( LPVOID lpParameter )\r
 139 {\r
 140         /* Just to prevent compiler warnings. */\r
 141         ( void ) lpParameter;\r
 142 \r
 143         for(;;)\r
 144         {\r
 145                 /* The timer is reset on each itteration of this loop rather than being set\r
 146                 to function periodicallys - this is for the reasons stated in the comments\r
 147                 where the timer is created. */\r
 148                 vPortTrace( "prvSimulatedPeripheralTimer: Tick acked, re-Sleeping()\r\n" );\r
 149 \r
 150                 /* Wait until the timer expires and we can access the pseudo interrupt \r
 151                 variables. */\r
 152                 Sleep( portTICK_RATE_MS );\r
 153 \r
 154                 vPortTrace( "prvSimulatedPeripheralTimer: Timer signalled, waiting interrupt event mutex\r\n" );\r
 155                 WaitForSingleObject( pvInterruptEventMutex, INFINITE );\r
 156                 vPortTrace( "prvSimulatedPeripheralTimer: Got interrupt event mutex\r\n" );\r
 157                 \r
 158                 /* The timer has expired, generate the simulated tick event. */\r
 159                 ulPendingInterrupts |= ( 1 << portINTERRUPT_TICK );\r
 160                 if( pvInterruptEvent != NULL )\r
 161                 {\r
 162                         vPortTrace( "prvSimulatedPeripheralTimer: Setting interrupt event to signal tick\r\n" );\r
 163                         SetEvent( pvInterruptEvent );\r
 164                 }\r
 165 \r
 166                 /* Give back the mutex so the pseudo interrupt handler unblocks and can\r
 167                 access the interrupt handler variables.  This high priority task will then\r
 168                 loop back round to wait for the lower priority psuedo interrupt handler \r
 169                 thread to acknowledge the tick. */\r
 170                 if( pvInterruptEventMutex != NULL )\r
 171                 {\r
 172                         vPortTrace( "prvSimulatedPeripheralTimer: Releasing interrupt event mutex so tick can be processed\r\n" );\r
 173                         ReleaseMutex( pvInterruptEventMutex );\r
 174                 }\r
 175 \r
 176                 /* Wait for the previous tick to be acknowledged before resetting the timer.\r
 177                 As mentioned above this is done to prevent timer overruns in the non real-\r
 178                 time environment.  THIS IS NOT HOW A REAL PORT SHOULD USE TIMERS! */\r
 179                 WaitForSingleObject( pvTickAcknowledgeEvent, INFINITE );\r
 180         }\r
 181 }\r
 182 /*-----------------------------------------------------------*/\r
 183 \r
 184 portSTACK_TYPE *pxPortInitialiseStack( portSTACK_TYPE *pxTopOfStack, pdTASK_CODE pxCode, void *pvParameters )\r
 185 {\r
 186 xThreadState *pxThreadState = NULL;\r
 187 \r
 188         /* In this simulated case a stack is not initialised, but instead a thread\r
 189         is created that will execute the task being created.  The thread handles\r
 190         the context switching itself.  The xThreadState object is placed onto\r
 191         the stack that was created for the task - so the stack buffer is still\r
 192         used, just not in the conventional way.  It will not be used for anything\r
 193         other than holding this structure. */\r
 194         pxThreadState = ( xThreadState * ) ( pxTopOfStack - sizeof( xThreadState ) );\r
 195 \r
 196                 /* Create the thread itself. */\r
 197                 pxThreadState->pvThread = ( void * ) CreateThread( NULL, 0, ( LPTHREAD_START_ROUTINE ) pxCode, pvParameters, CREATE_SUSPENDED, NULL );\r
 198                 pxThreadState->ulCriticalNesting = portNO_CRITICAL_NESTING;\r
 199                 pxThreadState->lWaitingInterruptAck = pdFALSE;\r
 200                 SetThreadPriority( pxThreadState->pvThread, THREAD_PRIORITY_IDLE );\r
 201         \r
 202         return ( portSTACK_TYPE * ) pxThreadState;\r
 203 }\r
 204 /*-----------------------------------------------------------*/\r
 205 \r
 206 portBASE_TYPE xPortStartScheduler( void )\r
 207 {\r
 208 void *pvHandle;\r
 209 long lSuccess = pdPASS;\r
 210 xThreadState *pxThreadState;\r
 211 \r
 212         /* Set the priority of this thread such that it is above the priority of the\r
 213         threads that run tasks, but below the priority of the thread that generates\r
 214         the pseudo tick interrupts.  This priority is chosen because this is the\r
 215         thread that actually handles the psuedo interrupts. */\r
 216         pvHandle = GetCurrentThread();\r
 217         if( pvHandle == NULL )\r
 218         {\r
 219                 lSuccess = pdFAIL;\r
 220         }\r
 221         \r
 222         if( lSuccess == pdPASS )\r
 223         {\r
 224                 if( SetThreadPriority( pvHandle, THREAD_PRIORITY_BELOW_NORMAL ) == 0 )\r
 225                 {\r
 226                         lSuccess = pdFAIL;\r
 227                 }\r
 228         }\r
 229 \r
 230         if( lSuccess == pdPASS )\r
 231         {\r
 232                 /* Create the events and mutexes that are used to synchronise all the\r
 233                 threads. */\r
 234                 pvInterruptEventMutex = CreateMutex( NULL, FALSE, NULL );\r
 235                 pvInterruptEvent = CreateEvent( NULL, FALSE, FALSE, NULL );\r
 236                 pvTickAcknowledgeEvent = CreateEvent( NULL, FALSE, FALSE, NULL );\r
 237                 pvInterruptAcknowledgeEvent = CreateEvent( NULL, FALSE, FALSE, NULL );\r
 238 \r
 239                 /* Start the thread that simulates the timer peripheral to generate\r
 240                 tick interrupts. */\r
 241                 pvHandle = CreateThread( NULL, 0, prvSimulatedPeripheralTimer, NULL, 0, NULL );\r
 242                 if( pvHandle != NULL )\r
 243                 {\r
 244                         SetThreadPriority( pvHandle, THREAD_PRIORITY_ABOVE_NORMAL );\r
 245                 }\r
 246                 \r
 247                 /* Start the highest priority task by obtaining its associated thread state\r
 248                 structure, in which is stored the thread handle. */\r
 249                 pxThreadState = ( xThreadState * ) *( ( unsigned long * ) pxCurrentTCB );\r
 250                 ulCriticalNesting = portNO_CRITICAL_NESTING;\r
 251 \r
 252                 vPortTrace( "Created system threads, starting task" );\r
 253 \r
 254                 ResumeThread( pxThreadState->pvThread );\r
 255         }       \r
 256         \r
 257         /* Handle all pseudo interrupts - including yield requests and simulated ticks. */\r
 258         prvProcessEvents();\r
 259 \r
 260         /* Would not expect to return from prvProcessEvents(), so should not get here. */\r
 261         return 0;\r
 262 }\r
 263 /*-----------------------------------------------------------*/\r
 264 \r
 265 static void prvProcessEvents( void )\r
 266 {\r
 267 long lSwitchRequired;\r
 268 xThreadState *pxThreadState;\r
 269 void *pvObjectList[ 2 ];\r
 270 unsigned long i;\r
 271 //char cTraceBuffer[ 256 ];\r
 272 \r
 273         vPortTrace( "Entering prvProcessEvents\r\n" );\r
 274 \r
 275         /* Going to block on the mutex that ensured exclusive access to the pdeudo \r
 276         interrupt objects, and the event that signals that an interrupt is waiting\r
 277         to be processed. */\r
 278         pvObjectList[ 0 ] = pvInterruptEventMutex;\r
 279         pvObjectList[ 1 ] = pvInterruptEvent;\r
 280 \r
 281         for(;;)\r
 282         {\r
 283                 vPortTrace( "prvProcessEvents: Waiting for next interrupt event\r\n" );\r
 284                 WaitForMultipleObjects( sizeof( pvObjectList ) / sizeof( void * ), pvObjectList, TRUE, INFINITE );\r
 285                 vPortTrace( "prvProcessEvents: Got interrupt event and mutex\r\n" );\r
 286                 //vPortTrace( "prvProcessEvents: Waiting for next interrupt event\r\n" );\r
 287                 //WaitForSingleObject( pvInterruptEvent, INFINITE );\r
 288                 //vPortTrace( "prvProcessEvents: Waiting interrupt event mutex to access interrupt data\r\n" );\r
 289                 //WaitForSingleObject( pvInterruptEventMutex, INFINITE );\r
 290 \r
 291                 lSwitchRequired = pdFALSE;\r
 292 \r
 293                 /* For each interrupt we are interested in processing, each of which is \r
 294                 represented by a bit in the 32bit ulPendingInterrupts variable. */\r
 295                 for( i = 0; i < portMAX_INTERRUPTS; i++ )\r
 296                 {\r
 297                         /* Is the pseudo interrupt pending? */\r
 298                         if( ulPendingInterrupts & ( 1UL << i ) )\r
 299                         {\r
 300                                 switch( i )\r
 301                                 {\r
 302                                         case portINTERRUPT_YIELD:\r
 303 \r
 304                                                 vPortTrace( "prvProcessEvents: Processing Yield\r\n" );\r
 305                                                 /* Yield interrupts occur no matter what the critical nesting count. */\r
 306                                                 lSwitchRequired = pdTRUE;\r
 307 \r
 308                                                 /* Clear the interrupt pending bit. */\r
 309                                                 ulPendingInterrupts &= ~( 1UL << portINTERRUPT_YIELD );\r
 310                                                 break;\r
 311 \r
 312                                         case portINTERRUPT_TICK:\r
 313                                         \r
 314                                                 /* Tick interrupts should only be processed if the critical nesting count\r
 315                                                 is zero.  The critical nesting count represents the interrupt mask on \r
 316                                                 real target hardware. */\r
 317                                                 vPortTrace( "prvProcessEvents: Processing tick event\r\n" );\r
 318                                                 if( ulCriticalNesting == 0 )\r
 319                                                 {\r
 320                                                         /* Process the tick itself. */\r
 321                                                         vPortTrace( "prvProcessEvents: Incrementing tick\r\n" );\r
 322                                                         vTaskIncrementTick();\r
 323                                                         #if( configUSE_PREEMPTION != 0 )\r
 324                                                         {\r
 325                                                                 /* A context switch is only automatically performed from the tick\r
 326                                                                 interrupt if the pre-emptive scheduler is being used. */\r
 327                                                                 lSwitchRequired = pdTRUE;\r
 328                                                         }\r
 329                                                         #endif\r
 330                                                         \r
 331                                                         vPortTrace( "prvProcessEvents: Acking tick\r\n" );\r
 332                                                         SetEvent( pvTickAcknowledgeEvent );\r
 333 \r
 334                                                         /* Clear the interrupt pending bit. */\r
 335                                                         ulPendingInterrupts &= ~( 1UL << portINTERRUPT_TICK );\r
 336                                                 }\r
 337                                                 break;\r
 338 \r
 339                                         default:\r
 340 \r
 341                                                 /* Is a handler installed? */\r
 342                                                 if( vIsrHandler[ i ] != NULL )\r
 343                                                 {\r
 344                                                         lSwitchRequired = pdTRUE;\r
 345 \r
 346                                                         /* Run the actual handler. */\r
 347                                                         vIsrHandler[ i ]();\r
 348 \r
 349                                                         /* Clear the interrupt pending bit. */\r
 350                                                         ulPendingInterrupts &= ~( 1UL << i );\r
 351 \r
 352                                                         /* TODO:  Need to have some sort of handshake event here for non-tick\r
 353                                                         and none yield interrupts. */\r
 354                                                 }\r
 355                                                 break;\r
 356                                 }\r
 357                         }\r
 358                 }\r
 359 \r
 360                 if( lSwitchRequired != pdFALSE )\r
 361                 {\r
 362                         void *pvOldCurrentTCB;\r
 363 \r
 364                         pvOldCurrentTCB = pxCurrentTCB;\r
 365 \r
 366                         /* Save the state of the current thread before suspending it. */\r
 367                         pxThreadState = ( xThreadState *) *( ( unsigned long * ) pxCurrentTCB );\r
 368                         pxThreadState->ulCriticalNesting = ulCriticalNesting ;\r
 369                         \r
 370                         /* Select the next task to run. */\r
 371                         vTaskSwitchContext();\r
 372                         \r
 373                         /* If the task selected to enter the running state is not the task\r
 374                         that is already in the running state. */\r
 375                         if( pvOldCurrentTCB != pxCurrentTCB )\r
 376                         {\r
 377                                 /* Suspend the old thread. */\r
 378                                 SuspendThread( pxThreadState->pvThread );\r
 379                                 //sprintf( cTraceBuffer, "Event processor: suspending %s, resuming %s\r\n", ((xTCB*)pvOldCurrentTCB)->pcTaskName, ((xTCB*)pxCurrentTCB)->pcTaskName );\r
 380                                 //vPortTrace( cTraceBuffer );\r
 381 \r
 382                                 /* Obtain the state of the task now selected to enter the Running state. */\r
 383                                 pxThreadState = ( xThreadState * ) ( *( unsigned long *) pxCurrentTCB );\r
 384                                 ulCriticalNesting = pxThreadState->ulCriticalNesting;\r
 385                                 ResumeThread( pxThreadState->pvThread );\r
 386 \r
 387                                 if( pxThreadState->lWaitingInterruptAck == pdTRUE )\r
 388                                 {\r
 389                                         pxThreadState->lWaitingInterruptAck = pdFALSE;\r
 390                                         vPortTrace( "prvProcessEvents: Acking interrupt\r\n" );\r
 391                                         SetEvent( pvInterruptAcknowledgeEvent );\r
 392                                 }\r
 393                         }\r
 394                 }\r
 395 \r
 396                 ReleaseMutex( pvInterruptEventMutex );\r
 397         }\r
 398 }\r
 399 /*-----------------------------------------------------------*/\r
 400 \r
 401 void vPortEndScheduler( void )\r
 402 {\r
 403 }\r
 404 /*-----------------------------------------------------------*/\r
 405 \r
 406 void vPortGeneratePseudoInterrupt( unsigned long ulInterruptNumber )\r
 407 {\r
 408 xThreadState *pxThreadState;\r
 409 \r
 410         if( ( ulInterruptNumber < portMAX_INTERRUPTS ) && ( pvInterruptEventMutex != NULL ) )\r
 411         {\r
 412                 /* Yield interrupts are processed even when critical nesting is non-zero. */\r
 413                 if( ( ulCriticalNesting == 0 ) || ( ulInterruptNumber == portINTERRUPT_YIELD ) )\r
 414                 {\r
 415                         WaitForSingleObject( pvInterruptEventMutex, INFINITE );\r
 416                         ulPendingInterrupts |= ( 1 << ulInterruptNumber );\r
 417 \r
 418                         /* The event handler needs to know to signal the interrupt acknowledge event\r
 419                         the next time this task runs. */\r
 420                         pxThreadState = ( xThreadState * ) *( ( unsigned long * ) pxCurrentTCB );\r
 421                         pxThreadState->lWaitingInterruptAck = pdTRUE;\r
 422 \r
 423                         vPortTrace( "vPortGeneratePseudoInterrupt: Got interrupt mutex, about to signal interrupt event\r\n" );\r
 424                         SetEvent( pvInterruptEvent );\r
 425                         vPortTrace( "vPortGeneratePseudoInterrupt: About to release interrupt event mutex\r\n" );\r
 426                         ReleaseMutex( pvInterruptEventMutex );\r
 427                         vPortTrace( "vPortGeneratePseudoInterrupt: Interrupt event mutex released, going to wait for interrupt ack\r\n" );\r
 428 \r
 429                         WaitForSingleObject( pvInterruptAcknowledgeEvent, INFINITE );\r
 430                         vPortTrace( "vPortGeneratePseudoInterrupt: Interrupt acknowledged, leaving vPortGeneratePseudoInterrupt()\r\n" );\r
 431                 }\r
 432         }\r
 433 }\r
 434 /*-----------------------------------------------------------*/\r
 435 \r
 436 void vPortSetInterruptHandler( unsigned long ulInterruptNumber, void (*pvHandler)( void ) )\r
 437 {\r
 438         if( ulInterruptNumber < portMAX_INTERRUPTS )\r
 439         {\r
 440                 if( pvInterruptEventMutex != NULL )\r
 441                 {\r
 442                         WaitForSingleObject( pvInterruptEventMutex, INFINITE );\r
 443                         vIsrHandler[ ulInterruptNumber ] = pvHandler;\r
 444                         ReleaseMutex( pvInterruptEventMutex );\r
 445                 }\r
 446                 else\r
 447                 {\r
 448                         vIsrHandler[ ulInterruptNumber ] = pvHandler;\r
 449                 }\r
 450         }\r
 451 }\r
 452 /*-----------------------------------------------------------*/\r
 453 \r
 454 void vPortEnterCritical( void )\r
 455 {\r
 456         ulCriticalNesting++;\r
 457 }\r
 458 /*-----------------------------------------------------------*/\r
 459 \r
 460 void vPortExitCritical( void )\r
 461 {\r
 462 xThreadState *pxThreadState;\r
 463 \r
 464         if( ulCriticalNesting > portNO_CRITICAL_NESTING )\r
 465         {\r
 466                 ulCriticalNesting--;\r
 467 \r
 468                 if( ulCriticalNesting == 0 )\r
 469                 {\r
 470                         /* Were any interrupts set to pending while interrupts were \r
 471                         (pseudo) disabled? */\r
 472                         if( ulPendingInterrupts != 0UL )\r
 473                         {\r
 474                                 WaitForSingleObject( pvInterruptEventMutex, INFINITE );\r
 475                                 vPortTrace( "vPortExitCritical:  Setting interrupt event\r\n" );\r
 476                                 SetEvent( pvInterruptEvent );\r
 477 \r
 478                                 /* The event handler needs to know to signal the interrupt acknowledge event\r
 479                                 the next time this task runs. */\r
 480                                 pxThreadState = ( xThreadState * ) *( ( unsigned long * ) pxCurrentTCB );\r
 481                                 pxThreadState->lWaitingInterruptAck = pdTRUE;\r
 482 \r
 483                                 ReleaseMutex( pvInterruptEventMutex );\r
 484 \r
 485                                 vPortTrace( "vPortExitCritical:  Waiting interrupt ack\r\n" );\r
 486                                 WaitForSingleObject( pvInterruptAcknowledgeEvent, INFINITE );\r
 487                                 vPortTrace( "vPortExitCritical: Interrupt acknowledged, leaving critical section code\r\n" );\r
 488                         }\r
 489                 }\r
 490         }\r
 491 }\r