2 FreeRTOS V6.1.0 - Copyright (C) 2010 Real Time Engineers Ltd.
\r
4 ***************************************************************************
\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
13 * then take a look at the FreeRTOS books - available as PDF or paperback *
\r
15 * "Using the FreeRTOS Real Time Kernel - a Practical Guide" *
\r
16 * http://www.FreeRTOS.org/Documentation *
\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
23 ***************************************************************************
\r
25 This file is part of the FreeRTOS distribution.
\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
44 http://www.FreeRTOS.org - Documentation, latest information, license and
\r
47 http://www.SafeRTOS.com - A version that is certified for use in safety
\r
50 http://www.OpenRTOS.com - Commercial support, development, porting,
\r
51 licensing and training services.
\r
54 /* Scheduler includes. */
\r
55 #include "FreeRTOS.h"
\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
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
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
71 static DWORD WINAPI prvSimulatedPeripheralTimer( LPVOID lpParameter );
\r
74 * Process all the simulated interrupts - each represented by a bit in
\r
75 * ulPendingInterrupts variable.
\r
77 static void prvProcessEvents( void );
\r
79 /*-----------------------------------------------------------*/
\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
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
93 /* Critical nesting count of the task - each task has its own. */
\r
94 portSTACK_TYPE ulCriticalNesting;
\r
96 /* Handle of the thread that executes the task. */
\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
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
107 static void *pvInterruptEvent = NULL;
\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
113 /* The main thread, which also acts as the pseudo interrupt handler. */
\r
114 static void *pvMainThreadAndInterrupHandler;
\r
116 /* Events used to manage sequencing. */
\r
117 static void *pvTickAcknowledgeEvent = NULL, *pvInterruptAcknowledgeEvent = NULL;
\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
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
133 /* Pointer to the TCB of the currently executing task. */
\r
134 extern void *pxCurrentTCB;
\r
136 /*-----------------------------------------------------------*/
\r
138 static DWORD WINAPI prvSimulatedPeripheralTimer( LPVOID lpParameter )
\r
141 LARGE_INTEGER liDueTime;
\r
142 void *pvObjectList[ 2 ];
\r
143 const long long ll_ms_In_100ns_units = ( long long ) -1000;
\r
145 /* Just to prevent compiler warnings. */
\r
146 ( void ) lpParameter;
\r
148 /* The timer is created as a one shot timer even though we want it to repeat
\r
149 at a given frequency. This is because Windows is not a real time environment,
\r
150 and attempting to set a high frequency periodic timer will result in event
\r
151 overruns. Therefore the timer is just reset after each time the pseudo
\r
152 interrupt handler has processed each tick event. */
\r
153 pvTimer = CreateWaitableTimer( NULL, TRUE, NULL );
\r
155 liDueTime.QuadPart = ( long long ) portTICK_RATE_MS * ll_ms_In_100ns_units;
\r
157 /* Block on the timer itself and the event mutex that grants access to the
\r
158 interrupt variables. */
\r
159 pvObjectList[ 0 ] = pvInterruptEventMutex;
\r
160 pvObjectList[ 1 ] = pvTimer;
\r
164 /* The timer is reset on each itteration of this loop rather than being set
\r
165 to function periodicallys - this is for the reasons stated in the comments
\r
166 where the timer is created. */
\r
167 vPortTrace( "prvSimulatedPeripheralTimer: Tick acked, setting new tick timer\r\n" );
\r
168 SetWaitableTimer( pvTimer, &liDueTime, 0, NULL, NULL, TRUE );
\r
170 /* Wait until the timer expires and we can access the pseudo interrupt
\r
172 //WaitForMultipleObjects( ( sizeof( pvObjectList ) / sizeof( void * ) ), pvObjectList, TRUE, INFINITE );
\r
173 WaitForSingleObject( pvTimer, INFINITE );
\r
174 vPortTrace( "prvSimulatedPeripheralTimer: Timer signalled, waiting interrupt event mutex\r\n" );
\r
175 WaitForSingleObject( pvInterruptEventMutex, INFINITE );
\r
176 vPortTrace( "prvSimulatedPeripheralTimer: Got interrupt event mutex\r\n" );
\r
178 /* The timer has expired, generate the simulated tick event. */
\r
179 ulPendingInterrupts |= ( 1 << portINTERRUPT_TICK );
\r
180 if( pvInterruptEvent != NULL )
\r
182 vPortTrace( "prvSimulatedPeripheralTimer: Setting interrupt event to signal tick\r\n" );
\r
183 SetEvent( pvInterruptEvent );
\r
186 /* Give back the mutex so the pseudo interrupt handler unblocks and can
\r
187 access the interrupt handler variables. This high priority task will then
\r
188 loop back round to wait for the lower priority psuedo interrupt handler
\r
189 thread to acknowledge the tick. */
\r
190 if( pvInterruptEventMutex != NULL )
\r
192 vPortTrace( "prvSimulatedPeripheralTimer: Releasing interrupt event mutex so tick can be processed\r\n" );
\r
193 ReleaseMutex( pvInterruptEventMutex );
\r
196 /* Wait for the previous tick to be acknowledged before resetting the timer.
\r
197 As mentioned above this is done to prevent timer overruns in the non real-
\r
198 time environment. THIS IS NOT HOW A REAL PORT SHOULD USE TIMERS! */
\r
199 WaitForSingleObject( pvTickAcknowledgeEvent, INFINITE );
\r
202 /*-----------------------------------------------------------*/
\r
204 portSTACK_TYPE *pxPortInitialiseStack( portSTACK_TYPE *pxTopOfStack, pdTASK_CODE pxCode, void *pvParameters )
\r
206 xThreadState *pxThreadState = NULL;
\r
208 /* In this simulated case a stack is not initialised, but instead a thread
\r
209 is created that will execute the task being created. The thread handles
\r
210 the context switching itself. The xThreadState object is placed onto
\r
211 the stack that was created for the task - so the stack buffer is still
\r
212 used, just not in the conventional way. It will not be used for anything
\r
213 other than holding this structure. */
\r
214 pxThreadState = ( xThreadState * ) ( pxTopOfStack - sizeof( xThreadState ) );
\r
216 /* Create the thread itself. */
\r
217 pxThreadState->pvThread = ( void * ) CreateThread( NULL, 0, ( LPTHREAD_START_ROUTINE ) pxCode, pvParameters, CREATE_SUSPENDED, NULL );
\r
218 pxThreadState->ulCriticalNesting = portNO_CRITICAL_NESTING;
\r
219 pxThreadState->lWaitingInterruptAck = pdFALSE;
\r
220 SetThreadPriority( pxThreadState->pvThread, THREAD_PRIORITY_IDLE );
\r
222 return ( portSTACK_TYPE * ) pxThreadState;
\r
224 /*-----------------------------------------------------------*/
\r
226 portBASE_TYPE xPortStartScheduler( void )
\r
229 long lSuccess = pdPASS;
\r
230 xThreadState *pxThreadState;
\r
232 /* Set the priority of this thread such that it is above the priority of the
\r
233 threads that run tasks, but below the priority of the thread that generates
\r
234 the pseudo tick interrupts. This priority is chosen because this is the
\r
235 thread that actually handles the psuedo interrupts. */
\r
236 pvHandle = GetCurrentThread();
\r
237 if( pvHandle == NULL )
\r
242 if( lSuccess == pdPASS )
\r
244 if( SetThreadPriority( pvHandle, THREAD_PRIORITY_BELOW_NORMAL ) == 0 )
\r
250 if( lSuccess == pdPASS )
\r
252 /* Create the events and mutexes that are used to synchronise all the
\r
254 pvInterruptEventMutex = CreateMutex( NULL, FALSE, NULL );
\r
255 pvInterruptEvent = CreateEvent( NULL, FALSE, FALSE, NULL );
\r
256 pvTickAcknowledgeEvent = CreateEvent( NULL, FALSE, FALSE, NULL );
\r
257 pvInterruptAcknowledgeEvent = CreateEvent( NULL, FALSE, FALSE, NULL );
\r
259 /* Start the thread that simulates the timer peripheral to generate
\r
260 tick interrupts. */
\r
261 pvHandle = CreateThread( NULL, 0, prvSimulatedPeripheralTimer, NULL, 0, NULL );
\r
262 if( pvHandle != NULL )
\r
264 SetThreadPriority( pvHandle, THREAD_PRIORITY_ABOVE_NORMAL );
\r
267 /* Start the highest priority task by obtaining its associated thread state
\r
268 structure, in which is stored the thread handle. */
\r
269 pxThreadState = ( xThreadState * ) *( ( unsigned long * ) pxCurrentTCB );
\r
270 ulCriticalNesting = portNO_CRITICAL_NESTING;
\r
272 vPortTrace( "Created system threads, starting task" );
\r
274 ResumeThread( pxThreadState->pvThread );
\r
277 /* Handle all pseudo interrupts - including yield requests and simulated ticks. */
\r
278 prvProcessEvents();
\r
280 /* Would not expect to return from prvProcessEvents(), so should not get here. */
\r
283 /*-----------------------------------------------------------*/
\r
285 static void prvProcessEvents( void )
\r
287 long lSwitchRequired;
\r
288 xThreadState *pxThreadState;
\r
289 void *pvObjectList[ 2 ];
\r
291 //char cTraceBuffer[ 256 ];
\r
293 vPortTrace( "Entering prvProcessEvents\r\n" );
\r
295 /* Going to block on the mutex that ensured exclusive access to the pdeudo
\r
296 interrupt objects, and the event that signals that an interrupt is waiting
\r
297 to be processed. */
\r
298 pvObjectList[ 0 ] = pvInterruptEventMutex;
\r
299 pvObjectList[ 1 ] = pvInterruptEvent;
\r
303 vPortTrace( "prvProcessEvents: Waiting for next interrupt event\r\n" );
\r
304 WaitForMultipleObjects( sizeof( pvObjectList ) / sizeof( void * ), pvObjectList, TRUE, INFINITE );
\r
305 vPortTrace( "prvProcessEvents: Got interrupt event and mutex\r\n" );
\r
306 //vPortTrace( "prvProcessEvents: Waiting for next interrupt event\r\n" );
\r
307 //WaitForSingleObject( pvInterruptEvent, INFINITE );
\r
308 //vPortTrace( "prvProcessEvents: Waiting interrupt event mutex to access interrupt data\r\n" );
\r
309 //WaitForSingleObject( pvInterruptEventMutex, INFINITE );
\r
311 lSwitchRequired = pdFALSE;
\r
313 /* For each interrupt we are interested in processing, each of which is
\r
314 represented by a bit in the 32bit ulPendingInterrupts variable. */
\r
315 for( i = 0; i < portMAX_INTERRUPTS; i++ )
\r
317 /* Is the pseudo interrupt pending? */
\r
318 if( ulPendingInterrupts & ( 1UL << i ) )
\r
322 case portINTERRUPT_YIELD:
\r
324 vPortTrace( "prvProcessEvents: Processing Yield\r\n" );
\r
325 /* Yield interrupts occur no matter what the critical nesting count. */
\r
326 lSwitchRequired = pdTRUE;
\r
328 /* Clear the interrupt pending bit. */
\r
329 ulPendingInterrupts &= ~( 1UL << portINTERRUPT_YIELD );
\r
332 case portINTERRUPT_TICK:
\r
334 /* Tick interrupts should only be processed if the critical nesting count
\r
335 is zero. The critical nesting count represents the interrupt mask on
\r
336 real target hardware. */
\r
337 vPortTrace( "prvProcessEvents: Processing tick event\r\n" );
\r
338 if( ulCriticalNesting == 0 )
\r
340 /* Process the tick itself. */
\r
341 vPortTrace( "prvProcessEvents: Incrementing tick\r\n" );
\r
342 vTaskIncrementTick();
\r
343 #if( configUSE_PREEMPTION != 0 )
\r
345 /* A context switch is only automatically performed from the tick
\r
346 interrupt if the pre-emptive scheduler is being used. */
\r
347 lSwitchRequired = pdTRUE;
\r
351 vPortTrace( "prvProcessEvents: Acking tick\r\n" );
\r
352 SetEvent( pvTickAcknowledgeEvent );
\r
354 /* Clear the interrupt pending bit. */
\r
355 ulPendingInterrupts &= ~( 1UL << portINTERRUPT_TICK );
\r
361 /* Is a handler installed? */
\r
362 if( vIsrHandler[ i ] != NULL )
\r
364 lSwitchRequired = pdTRUE;
\r
366 /* Run the actual handler. */
\r
367 vIsrHandler[ i ]();
\r
369 /* Clear the interrupt pending bit. */
\r
370 ulPendingInterrupts &= ~( 1UL << i );
\r
372 /* TODO: Need to have some sort of handshake event here for non-tick
\r
373 and none yield interrupts. */
\r
380 if( lSwitchRequired != pdFALSE )
\r
382 void *pvOldCurrentTCB;
\r
384 pvOldCurrentTCB = pxCurrentTCB;
\r
386 /* Save the state of the current thread before suspending it. */
\r
387 pxThreadState = ( xThreadState *) *( ( unsigned long * ) pxCurrentTCB );
\r
388 pxThreadState->ulCriticalNesting = ulCriticalNesting ;
\r
390 /* Select the next task to run. */
\r
391 vTaskSwitchContext();
\r
393 /* If the task selected to enter the running state is not the task
\r
394 that is already in the running state. */
\r
395 if( pvOldCurrentTCB != pxCurrentTCB )
\r
397 /* Suspend the old thread. */
\r
398 SuspendThread( pxThreadState->pvThread );
\r
399 //sprintf( cTraceBuffer, "Event processor: suspending %s, resuming %s\r\n", ((xTCB*)pvOldCurrentTCB)->pcTaskName, ((xTCB*)pxCurrentTCB)->pcTaskName );
\r
400 //vPortTrace( cTraceBuffer );
\r
402 /* Obtain the state of the task now selected to enter the Running state. */
\r
403 pxThreadState = ( xThreadState * ) ( *( unsigned long *) pxCurrentTCB );
\r
404 ulCriticalNesting = pxThreadState->ulCriticalNesting;
\r
405 ResumeThread( pxThreadState->pvThread );
\r
407 if( pxThreadState->lWaitingInterruptAck == pdTRUE )
\r
409 pxThreadState->lWaitingInterruptAck = pdFALSE;
\r
410 vPortTrace( "prvProcessEvents: Acking interrupt\r\n" );
\r
411 SetEvent( pvInterruptAcknowledgeEvent );
\r
416 ReleaseMutex( pvInterruptEventMutex );
\r
419 /*-----------------------------------------------------------*/
\r
421 void vPortEndScheduler( void )
\r
424 /*-----------------------------------------------------------*/
\r
426 void vPortGeneratePseudoInterrupt( unsigned long ulInterruptNumber )
\r
428 xThreadState *pxThreadState;
\r
430 if( ( ulInterruptNumber < portMAX_INTERRUPTS ) && ( pvInterruptEventMutex != NULL ) )
\r
432 /* Yield interrupts are processed even when critical nesting is non-zero. */
\r
433 if( ( ulCriticalNesting == 0 ) || ( ulInterruptNumber == portINTERRUPT_YIELD ) )
\r
435 WaitForSingleObject( pvInterruptEventMutex, INFINITE );
\r
436 ulPendingInterrupts |= ( 1 << ulInterruptNumber );
\r
438 /* The event handler needs to know to signal the interrupt acknowledge event
\r
439 the next time this task runs. */
\r
440 pxThreadState = ( xThreadState * ) *( ( unsigned long * ) pxCurrentTCB );
\r
441 pxThreadState->lWaitingInterruptAck = pdTRUE;
\r
443 vPortTrace( "vPortGeneratePseudoInterrupt: Got interrupt mutex, about to signal interrupt event\r\n" );
\r
444 SetEvent( pvInterruptEvent );
\r
445 vPortTrace( "vPortGeneratePseudoInterrupt: About to release interrupt event mutex\r\n" );
\r
446 ReleaseMutex( pvInterruptEventMutex );
\r
447 vPortTrace( "vPortGeneratePseudoInterrupt: Interrupt event mutex released, going to wait for interrupt ack\r\n" );
\r
449 WaitForSingleObject( pvInterruptAcknowledgeEvent, INFINITE );
\r
450 vPortTrace( "vPortGeneratePseudoInterrupt: Interrupt acknowledged, leaving vPortGeneratePseudoInterrupt()\r\n" );
\r
454 /*-----------------------------------------------------------*/
\r
456 void vPortSetInterruptHandler( unsigned long ulInterruptNumber, void (*pvHandler)( void ) )
\r
458 if( ulInterruptNumber < portMAX_INTERRUPTS )
\r
460 if( pvInterruptEventMutex != NULL )
\r
462 WaitForSingleObject( pvInterruptEventMutex, INFINITE );
\r
463 vIsrHandler[ ulInterruptNumber ] = pvHandler;
\r
464 ReleaseMutex( pvInterruptEventMutex );
\r
468 vIsrHandler[ ulInterruptNumber ] = pvHandler;
\r
472 /*-----------------------------------------------------------*/
\r
474 void vPortEnterCritical( void )
\r
476 ulCriticalNesting++;
\r
478 /*-----------------------------------------------------------*/
\r
480 void vPortExitCritical( void )
\r
482 xThreadState *pxThreadState;
\r
484 if( ulCriticalNesting > portNO_CRITICAL_NESTING )
\r
486 ulCriticalNesting--;
\r
488 if( ulCriticalNesting == 0 )
\r
490 /* Were any interrupts set to pending while interrupts were
\r
491 (pseudo) disabled? */
\r
492 if( ulPendingInterrupts != 0UL )
\r
494 WaitForSingleObject( pvInterruptEventMutex, INFINITE );
\r
495 vPortTrace( "vPortExitCritical: Setting interrupt event\r\n" );
\r
496 SetEvent( pvInterruptEvent );
\r
498 /* The event handler needs to know to signal the interrupt acknowledge event
\r
499 the next time this task runs. */
\r
500 pxThreadState = ( xThreadState * ) *( ( unsigned long * ) pxCurrentTCB );
\r
501 pxThreadState->lWaitingInterruptAck = pdTRUE;
\r
503 ReleaseMutex( pvInterruptEventMutex );
\r
505 vPortTrace( "vPortExitCritical: Waiting interrupt ack\r\n" );
\r
506 WaitForSingleObject( pvInterruptAcknowledgeEvent, INFINITE );
\r
507 vPortTrace( "vPortExitCritical: Interrupt acknowledged, leaving critical section code\r\n" );
\r