FreeRTOS/Source/portable/MSVC-MingW/port.c - nest-yale-lock/1.0.1/freertos - Git at Google

 /*
     FreeRTOS V8.0.1 - Copyright (C) 2014 Real Time Engineers Ltd.
     All rights reserved

     VISIT http://www.FreeRTOS.org TO ENSURE YOU ARE USING THE LATEST VERSION.

     ***************************************************************************
      *                                                                       *
      *    FreeRTOS provides completely free yet professionally developed,    *
      *    robust, strictly quality controlled, supported, and cross          *
      *    platform software that has become a de facto standard.             *
      *                                                                       *
      *    Help yourself get started quickly and support the FreeRTOS         *
      *    project by purchasing a FreeRTOS tutorial book, reference          *
      *    manual, or both from: http://www.FreeRTOS.org/Documentation        *
      *                                                                       *
      *    Thank you!                                                         *
      *                                                                       *
     ***************************************************************************

     This file is part of the FreeRTOS distribution.

     FreeRTOS is free software; you can redistribute it and/or modify it under
     the terms of the GNU General Public License (version 2) as published by the
     Free Software Foundation >>!AND MODIFIED BY!<< the FreeRTOS exception.

     >>!   NOTE: The modification to the GPL is included to allow you to     !<<
     >>!   distribute a combined work that includes FreeRTOS without being   !<<
     >>!   obliged to provide the source code for proprietary components     !<<
     >>!   outside of the FreeRTOS kernel.                                   !<<

     FreeRTOS is distributed in the hope that it will be useful, but WITHOUT ANY
     WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
     FOR A PARTICULAR PURPOSE.  Full license text is available from the following
     link: http://www.freertos.org/a00114.html

     1 tab == 4 spaces!

     ***************************************************************************
      *                                                                       *
      *    Having a problem?  Start by reading the FAQ "My application does   *
      *    not run, what could be wrong?"                                     *
      *                                                                       *
      *    http://www.FreeRTOS.org/FAQHelp.html                               *
      *                                                                       *
     ***************************************************************************

     http://www.FreeRTOS.org - Documentation, books, training, latest versions,
     license and Real Time Engineers Ltd. contact details.

     http://www.FreeRTOS.org/plus - A selection of FreeRTOS ecosystem products,
     including FreeRTOS+Trace - an indispensable productivity tool, a DOS
     compatible FAT file system, and our tiny thread aware UDP/IP stack.

     http://www.OpenRTOS.com - Real Time Engineers ltd license FreeRTOS to High
     Integrity Systems to sell under the OpenRTOS brand.  Low cost OpenRTOS
     licenses offer ticketed support, indemnification and middleware.

     http://www.SafeRTOS.com - High Integrity Systems also provide a safety
     engineered and independently SIL3 certified version for use in safety and
     mission critical applications that require provable dependability.

     1 tab == 4 spaces!
 */

 /* Scheduler includes. */
 #include "FreeRTOS.h"
 #include "task.h"
 #include <stdio.h>

 #ifdef __GNUC__
 	#include "mmsystem.h"
 #else
 	#pragma comment(lib, "winmm.lib")
 #endif

 #define portMAX_INTERRUPTS				( ( uint32_t ) sizeof( uint32_t ) * 8UL ) /* The number of bits in an uint32_t. */
 #define portNO_CRITICAL_NESTING 		( ( uint32_t ) 0 )

 /*
  * Created as a high priority thread, this function uses a timer to simulate
  * a tick interrupt being generated on an embedded target.  In this Windows
  * environment the timer does not achieve anything approaching real time
  * performance though.
  */
 static DWORD WINAPI prvSimulatedPeripheralTimer( LPVOID lpParameter );

 /*
  * Process all the simulated interrupts - each represented by a bit in
  * ulPendingInterrupts variable.
  */
 static void prvProcessSimulatedInterrupts( void );

 /*
  * Interrupt handlers used by the kernel itself.  These are executed from the
  * simulated interrupt handler thread.
  */
 static uint32_t prvProcessYieldInterrupt( void );
 static uint32_t prvProcessTickInterrupt( void );

 /*
  * Called when the process exits to let Windows know the high timer resolution
  * is no longer required.
  */
 static BOOL WINAPI prvEndProcess( DWORD dwCtrlType );

 /*-----------------------------------------------------------*/

 /* The WIN32 simulator runs each task in a thread.  The context switching is
 managed by the threads, so the task stack does not have to be managed directly,
 although the task stack is still used to hold an xThreadState structure this is
 the only thing it will ever hold.  The structure indirectly maps the task handle
 to a thread handle. */
 typedef struct
 {
 	/* Handle of the thread that executes the task. */
 	void *pvThread;

 } xThreadState;

 /* Simulated interrupts waiting to be processed.  This is a bit mask where each
 bit represents one interrupt, so a maximum of 32 interrupts can be simulated. */
 static volatile uint32_t ulPendingInterrupts = 0UL;

 /* An event used to inform the simulated interrupt processing thread (a high
 priority thread that simulated interrupt processing) that an interrupt is
 pending. */
 static void *pvInterruptEvent = NULL;

 /* Mutex used to protect all the simulated interrupt variables that are accessed
 by multiple threads. */
 static void *pvInterruptEventMutex = NULL;

 /* The critical nesting count for the currently executing task.  This is
 initialised to a non-zero value so interrupts do not become enabled during
 the initialisation phase.  As each task has its own critical nesting value
 ulCriticalNesting will get set to zero when the first task runs.  This
 initialisation is probably not critical in this simulated environment as the
 simulated interrupt handlers do not get created until the FreeRTOS scheduler is
 started anyway. */
 static uint32_t ulCriticalNesting = 9999UL;

 /* Handlers for all the simulated software interrupts.  The first two positions
 are used for the Yield and Tick interrupts so are handled slightly differently,
 all the other interrupts can be user defined. */
 static uint32_t (*ulIsrHandler[ portMAX_INTERRUPTS ])( void ) = { 0 };

 /* Pointer to the TCB of the currently executing task. */
 extern void *pxCurrentTCB;

 /* Used to ensure nothing is processed during the startup sequence. */
 static BaseType_t xPortRunning = pdFALSE;

 /*-----------------------------------------------------------*/

 static DWORD WINAPI prvSimulatedPeripheralTimer( LPVOID lpParameter )
 {
 TickType_t xMinimumWindowsBlockTime;
 TIMECAPS xTimeCaps;

 	/* Set the timer resolution to the maximum possible. */
 	if( timeGetDevCaps( &xTimeCaps, sizeof( xTimeCaps ) ) == MMSYSERR_NOERROR )
 	{
 		xMinimumWindowsBlockTime = ( TickType_t ) xTimeCaps.wPeriodMin;
 		timeBeginPeriod( xTimeCaps.wPeriodMin );

 		/* Register an exit handler so the timeBeginPeriod() function can be
 		matched with a timeEndPeriod() when the application exits. */
 		SetConsoleCtrlHandler( prvEndProcess, TRUE );
 	}
 	else
 	{
 		xMinimumWindowsBlockTime = ( TickType_t ) 20;
 	}

 	/* Just to prevent compiler warnings. */
 	( void ) lpParameter;

 	for(;;)
 	{
 		/* Wait until the timer expires and we can access the simulated interrupt
 		variables.  *NOTE* this is not a 'real time' way of generating tick
 		events as the next wake time should be relative to the previous wake
 		time, not the time that Sleep() is called.  It is done this way to
 		prevent overruns in this very non real time simulated/emulated
 		environment. */
 		if( portTICK_PERIOD_MS < xMinimumWindowsBlockTime )
 		{
 			Sleep( xMinimumWindowsBlockTime );
 		}
 		else
 		{
 			Sleep( portTICK_PERIOD_MS );
 		}

 		configASSERT( xPortRunning );

 		WaitForSingleObject( pvInterruptEventMutex, INFINITE );

 		/* The timer has expired, generate the simulated tick event. */
 		ulPendingInterrupts |= ( 1 << portINTERRUPT_TICK );

 		/* The interrupt is now pending - notify the simulated interrupt
 		handler thread. */
 		if( ulCriticalNesting == 0 )
 		{
 			SetEvent( pvInterruptEvent );
 		}

 		/* Give back the mutex so the simulated interrupt handler unblocks
 		and can	access the interrupt handler variables. */
 		ReleaseMutex( pvInterruptEventMutex );
 	}

 	#ifdef __GNUC__
 		/* Should never reach here - MingW complains if you leave this line out,
 		MSVC complains if you put it in. */
 		return 0;
 	#endif
 }
 /*-----------------------------------------------------------*/

 static BOOL WINAPI prvEndProcess( DWORD dwCtrlType )
 {
 TIMECAPS xTimeCaps;

 	( void ) dwCtrlType;

 	if( timeGetDevCaps( &xTimeCaps, sizeof( xTimeCaps ) ) == MMSYSERR_NOERROR )
 	{
 		/* Match the call to timeBeginPeriod( xTimeCaps.wPeriodMin ) made when
 		the process started with a timeEndPeriod() as the process exits. */
 		timeEndPeriod( xTimeCaps.wPeriodMin );
 	}

 	return pdPASS;
 }
 /*-----------------------------------------------------------*/

 StackType_t *pxPortInitialiseStack( StackType_t *pxTopOfStack, TaskFunction_t pxCode, void *pvParameters )
 {
 xThreadState *pxThreadState = NULL;
 int8_t *pcTopOfStack = ( int8_t * ) pxTopOfStack;

 	/* In this simulated case a stack is not initialised, but instead a thread
 	is created that will execute the task being created.  The thread handles
 	the context switching itself.  The xThreadState object is placed onto
 	the stack that was created for the task - so the stack buffer is still
 	used, just not in the conventional way.  It will not be used for anything
 	other than holding this structure. */
 	pxThreadState = ( xThreadState * ) ( pcTopOfStack - sizeof( xThreadState ) );

 	/* Create the thread itself. */
 	pxThreadState->pvThread = CreateThread( NULL, 0, ( LPTHREAD_START_ROUTINE ) pxCode, pvParameters, CREATE_SUSPENDED, NULL );
 	configASSERT( pxThreadState->pvThread );
 	SetThreadAffinityMask( pxThreadState->pvThread, 0x01 );
 	SetThreadPriorityBoost( pxThreadState->pvThread, TRUE );
 	SetThreadPriority( pxThreadState->pvThread, THREAD_PRIORITY_IDLE );

 	return ( StackType_t * ) pxThreadState;
 }
 /*-----------------------------------------------------------*/

 BaseType_t xPortStartScheduler( void )
 {
 void *pvHandle;
 int32_t lSuccess = pdPASS;
 xThreadState *pxThreadState;

 	/* Install the interrupt handlers used by the scheduler itself. */
 	vPortSetInterruptHandler( portINTERRUPT_YIELD, prvProcessYieldInterrupt );
 	vPortSetInterruptHandler( portINTERRUPT_TICK, prvProcessTickInterrupt );

 	/* Create the events and mutexes that are used to synchronise all the
 	threads. */
 	pvInterruptEventMutex = CreateMutex( NULL, FALSE, NULL );
 	pvInterruptEvent = CreateEvent( NULL, FALSE, FALSE, NULL );

 	if( ( pvInterruptEventMutex == NULL ) || ( pvInterruptEvent == NULL ) )
 	{
 		lSuccess = pdFAIL;
 	}

 	/* Set the priority of this thread such that it is above the priority of
 	the threads that run tasks.  This higher priority is required to ensure
 	simulated interrupts take priority over tasks. */
 	pvHandle = GetCurrentThread();
 	if( pvHandle == NULL )
 	{
 		lSuccess = pdFAIL;
 	}

 	if( lSuccess == pdPASS )
 	{
 		if( SetThreadPriority( pvHandle, THREAD_PRIORITY_NORMAL ) == 0 )
 		{
 			lSuccess = pdFAIL;
 		}
 		SetThreadPriorityBoost( pvHandle, TRUE );
 		SetThreadAffinityMask( pvHandle, 0x01 );
 	}

 	if( lSuccess == pdPASS )
 	{
 		/* Start the thread that simulates the timer peripheral to generate
 		tick interrupts.  The priority is set below that of the simulated
 		interrupt handler so the interrupt event mutex is used for the
 		handshake / overrun protection. */
 		pvHandle = CreateThread( NULL, 0, prvSimulatedPeripheralTimer, NULL, 0, NULL );
 		if( pvHandle != NULL )
 		{
 			SetThreadPriority( pvHandle, THREAD_PRIORITY_BELOW_NORMAL );
 			SetThreadPriorityBoost( pvHandle, TRUE );
 			SetThreadAffinityMask( pvHandle, 0x01 );
 		}

 		/* Start the highest priority task by obtaining its associated thread
 		state structure, in which is stored the thread handle. */
 		pxThreadState = ( xThreadState * ) *( ( uint32_t * ) pxCurrentTCB );
 		ulCriticalNesting = portNO_CRITICAL_NESTING;

 		/* Bump up the priority of the thread that is going to run, in the
 		hope that this will assist in getting the Windows thread scheduler to
 		behave as an embedded engineer might expect. */
 		ResumeThread( pxThreadState->pvThread );

 		/* Handle all simulated interrupts - including yield requests and
 		simulated ticks. */
 		prvProcessSimulatedInterrupts();
 	}

 	/* Would not expect to return from prvProcessSimulatedInterrupts(), so should
 	not get here. */
 	return 0;
 }
 /*-----------------------------------------------------------*/

 static uint32_t prvProcessYieldInterrupt( void )
 {
 	return pdTRUE;
 }
 /*-----------------------------------------------------------*/

 static uint32_t prvProcessTickInterrupt( void )
 {
 uint32_t ulSwitchRequired;

 	/* Process the tick itself. */
 	configASSERT( xPortRunning );
 	ulSwitchRequired = ( uint32_t ) xTaskIncrementTick();

 	return ulSwitchRequired;
 }
 /*-----------------------------------------------------------*/

 static void prvProcessSimulatedInterrupts( void )
 {
 uint32_t ulSwitchRequired, i;
 xThreadState *pxThreadState;
 void *pvObjectList[ 2 ];

 	/* Going to block on the mutex that ensured exclusive access to the simulated
 	interrupt objects, and the event that signals that a simulated interrupt
 	should be processed. */
 	pvObjectList[ 0 ] = pvInterruptEventMutex;
 	pvObjectList[ 1 ] = pvInterruptEvent;

 	/* Create a pending tick to ensure the first task is started as soon as
 	this thread pends. */
 	ulPendingInterrupts |= ( 1 << portINTERRUPT_TICK );
 	SetEvent( pvInterruptEvent );

 	xPortRunning = pdTRUE;

 	for(;;)
 	{
 		WaitForMultipleObjects( sizeof( pvObjectList ) / sizeof( void * ), pvObjectList, TRUE, INFINITE );

 		/* Used to indicate whether the simulated interrupt processing has
 		necessitated a context switch to another task/thread. */
 		ulSwitchRequired = pdFALSE;

 		/* For each interrupt we are interested in processing, each of which is
 		represented by a bit in the 32bit ulPendingInterrupts variable. */
 		for( i = 0; i < portMAX_INTERRUPTS; i++ )
 		{
 			/* Is the simulated interrupt pending? */
 			if( ulPendingInterrupts & ( 1UL << i ) )
 			{
 				/* Is a handler installed? */
 				if( ulIsrHandler[ i ] != NULL )
 				{
 					/* Run the actual handler. */
 					if( ulIsrHandler[ i ]() != pdFALSE )
 					{
 						ulSwitchRequired |= ( 1 << i );
 					}
 				}

 				/* Clear the interrupt pending bit. */
 				ulPendingInterrupts &= ~( 1UL << i );
 			}
 		}

 		if( ulSwitchRequired != pdFALSE )
 		{
 			void *pvOldCurrentTCB;

 			pvOldCurrentTCB = pxCurrentTCB;

 			/* Select the next task to run. */
 			vTaskSwitchContext();

 			/* If the task selected to enter the running state is not the task
 			that is already in the running state. */
 			if( pvOldCurrentTCB != pxCurrentTCB )
 			{
 				/* Suspend the old thread. */
 				pxThreadState = ( xThreadState *) *( ( uint32_t * ) pvOldCurrentTCB );
 				SuspendThread( pxThreadState->pvThread );

 				/* Obtain the state of the task now selected to enter the
 				Running state. */
 				pxThreadState = ( xThreadState * ) ( *( uint32_t *) pxCurrentTCB );
 				ResumeThread( pxThreadState->pvThread );
 			}
 		}

 		ReleaseMutex( pvInterruptEventMutex );
 	}
 }
 /*-----------------------------------------------------------*/

 void vPortDeleteThread( void *pvTaskToDelete )
 {
 xThreadState *pxThreadState;
 uint32_t ulErrorCode;

 	/* Remove compiler warnings if configASSERT() is not defined. */
 	( void ) ulErrorCode;

 	/* Find the handle of the thread being deleted. */
 	pxThreadState = ( xThreadState * ) ( *( uint32_t *) pvTaskToDelete );

 	/* Check that the thread is still valid, it might have been closed by
 	vPortCloseRunningThread() - which will be the case if the task associated
 	with the thread originally deleted itself rather than being deleted by a
 	different task. */
 	if( pxThreadState->pvThread != NULL )
 	{
 		WaitForSingleObject( pvInterruptEventMutex, INFINITE );

 		ulErrorCode = TerminateThread( pxThreadState->pvThread, 0 );
 		configASSERT( ulErrorCode );

 		ulErrorCode = CloseHandle( pxThreadState->pvThread );
 		configASSERT( ulErrorCode );

 		ReleaseMutex( pvInterruptEventMutex );
 	}
 }
 /*-----------------------------------------------------------*/

 void vPortCloseRunningThread( void *pvTaskToDelete, volatile BaseType_t *pxPendYield )
 {
 xThreadState *pxThreadState;
 void *pvThread;
 uint32_t ulErrorCode;

 	/* Remove compiler warnings if configASSERT() is not defined. */
 	( void ) ulErrorCode;

 	/* Find the handle of the thread being deleted. */
 	pxThreadState = ( xThreadState * ) ( *( uint32_t *) pvTaskToDelete );
 	pvThread = pxThreadState->pvThread;

 	/* Raise the Windows priority of the thread to ensure the FreeRTOS scheduler
 	does not run and swap it out before it is closed.  If that were to happen
 	the thread would never run again and effectively be a thread handle and
 	memory leak. */
 	SetThreadPriority( pvThread, THREAD_PRIORITY_ABOVE_NORMAL );

 	/* This function will not return, therefore a yield is set as pending to
 	ensure a context switch occurs away from this thread on the next tick. */
 	*pxPendYield = pdTRUE;

 	/* Mark the thread associated with this task as invalid so
 	vPortDeleteThread() does not try to terminate it. */
 	pxThreadState->pvThread = NULL;

 	/* Close the thread. */
 	ulErrorCode = CloseHandle( pvThread );
 	configASSERT( ulErrorCode );

 	ExitThread( 0 );
 }
 /*-----------------------------------------------------------*/

 void vPortEndScheduler( void )
 {
 	/* This function IS NOT TESTED! */
 	TerminateProcess( GetCurrentProcess(), 0 );
 }
 /*-----------------------------------------------------------*/

 void vPortGenerateSimulatedInterrupt( uint32_t ulInterruptNumber )
 {
 	configASSERT( xPortRunning );

 	if( ( ulInterruptNumber < portMAX_INTERRUPTS ) && ( pvInterruptEventMutex != NULL ) )
 	{
 		/* Yield interrupts are processed even when critical nesting is non-zero. */
 		WaitForSingleObject( pvInterruptEventMutex, INFINITE );
 		ulPendingInterrupts |= ( 1 << ulInterruptNumber );

 		/* The simulated interrupt is now held pending, but don't actually process it
 		yet if this call is within a critical section.  It is possible for this to
 		be in a critical section as calls to wait for mutexes are accumulative. */
 		if( ulCriticalNesting == 0 )
 		{
 			SetEvent( pvInterruptEvent );
 		}

 		ReleaseMutex( pvInterruptEventMutex );
 	}
 }
 /*-----------------------------------------------------------*/

 void vPortSetInterruptHandler( uint32_t ulInterruptNumber, uint32_t (*pvHandler)( void ) )
 {
 	if( ulInterruptNumber < portMAX_INTERRUPTS )
 	{
 		if( pvInterruptEventMutex != NULL )
 		{
 			WaitForSingleObject( pvInterruptEventMutex, INFINITE );
 			ulIsrHandler[ ulInterruptNumber ] = pvHandler;
 			ReleaseMutex( pvInterruptEventMutex );
 		}
 		else
 		{
 			ulIsrHandler[ ulInterruptNumber ] = pvHandler;
 		}
 	}
 }
 /*-----------------------------------------------------------*/

 void vPortEnterCritical( void )
 {
 	if( xPortRunning == pdTRUE )
 	{
 		/* The interrupt event mutex is held for the entire critical section,
 		effectively disabling (simulated) interrupts. */
 		WaitForSingleObject( pvInterruptEventMutex, INFINITE );
 		ulCriticalNesting++;
 	}
 	else
 	{
 		ulCriticalNesting++;
 	}
 }
 /*-----------------------------------------------------------*/

 void vPortExitCritical( void )
 {
 int32_t lMutexNeedsReleasing;

 	/* The interrupt event mutex should already be held by this thread as it was
 	obtained on entry to the critical section. */

 	lMutexNeedsReleasing = pdTRUE;

 	if( ulCriticalNesting > portNO_CRITICAL_NESTING )
 	{
 		if( ulCriticalNesting == ( portNO_CRITICAL_NESTING + 1 ) )
 		{
 			ulCriticalNesting--;

 			/* Were any interrupts set to pending while interrupts were
 			(simulated) disabled? */
 			if( ulPendingInterrupts != 0UL )
 			{
 				configASSERT( xPortRunning );
 				SetEvent( pvInterruptEvent );

 				/* Mutex will be released now, so does not require releasing
 				on function exit. */
 				lMutexNeedsReleasing = pdFALSE;
 				ReleaseMutex( pvInterruptEventMutex );
 			}
 		}
 		else
 		{
 			/* Tick interrupts will still not be processed as the critical
 			nesting depth will not be zero. */
 			ulCriticalNesting--;
 		}
 	}

 	if( pvInterruptEventMutex != NULL )
 	{
 		if( lMutexNeedsReleasing == pdTRUE )
 		{
 			configASSERT( xPortRunning );
 			ReleaseMutex( pvInterruptEventMutex );
 		}
 	}
 }
 /*-----------------------------------------------------------*/
	/*
	FreeRTOS V8.0.1 - Copyright (C) 2014 Real Time Engineers Ltd.
	All rights reserved

	VISIT http://www.FreeRTOS.org TO ENSURE YOU ARE USING THE LATEST VERSION.

	***************************************************************************
	* *
	* FreeRTOS provides completely free yet professionally developed, *
	* robust, strictly quality controlled, supported, and cross *
	* platform software that has become a de facto standard. *
	* *
	* Help yourself get started quickly and support the FreeRTOS *
	* project by purchasing a FreeRTOS tutorial book, reference *
	* manual, or both from: http://www.FreeRTOS.org/Documentation *
	* *
	* Thank you! *
	* *
	***************************************************************************

	This file is part of the FreeRTOS distribution.

	FreeRTOS is free software; you can redistribute it and/or modify it under
	the terms of the GNU General Public License (version 2) as published by the
	Free Software Foundation >>!AND MODIFIED BY!<< the FreeRTOS exception.

	>>! NOTE: The modification to the GPL is included to allow you to !<<
	>>! distribute a combined work that includes FreeRTOS without being !<<
	>>! obliged to provide the source code for proprietary components !<<
	>>! outside of the FreeRTOS kernel. !<<

	FreeRTOS is distributed in the hope that it will be useful, but WITHOUT ANY
	WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
	FOR A PARTICULAR PURPOSE. Full license text is available from the following
	link: http://www.freertos.org/a00114.html

	1 tab == 4 spaces!

	***************************************************************************
	* *
	* Having a problem? Start by reading the FAQ "My application does *
	* not run, what could be wrong?" *
	* *
	* http://www.FreeRTOS.org/FAQHelp.html *
	* *
	***************************************************************************

	http://www.FreeRTOS.org - Documentation, books, training, latest versions,
	license and Real Time Engineers Ltd. contact details.

	http://www.FreeRTOS.org/plus - A selection of FreeRTOS ecosystem products,
	including FreeRTOS+Trace - an indispensable productivity tool, a DOS
	compatible FAT file system, and our tiny thread aware UDP/IP stack.

	http://www.OpenRTOS.com - Real Time Engineers ltd license FreeRTOS to High
	Integrity Systems to sell under the OpenRTOS brand. Low cost OpenRTOS
	licenses offer ticketed support, indemnification and middleware.

	http://www.SafeRTOS.com - High Integrity Systems also provide a safety
	engineered and independently SIL3 certified version for use in safety and
	mission critical applications that require provable dependability.

	1 tab == 4 spaces!
	*/

	/* Scheduler includes. */
	#include "FreeRTOS.h"
	#include "task.h"
	#include <stdio.h>

	#ifdef __GNUC__
	#include "mmsystem.h"
	#else
	#pragma comment(lib, "winmm.lib")
	#endif

	#define portMAX_INTERRUPTS ( ( uint32_t ) sizeof( uint32_t ) * 8UL ) /* The number of bits in an uint32_t. */
	#define portNO_CRITICAL_NESTING ( ( uint32_t ) 0 )

	/*
	* Created as a high priority thread, this function uses a timer to simulate
	* a tick interrupt being generated on an embedded target. In this Windows
	* environment the timer does not achieve anything approaching real time
	* performance though.
	*/
	static DWORD WINAPI prvSimulatedPeripheralTimer( LPVOID lpParameter );

	/*
	* Process all the simulated interrupts - each represented by a bit in
	* ulPendingInterrupts variable.
	*/
	static void prvProcessSimulatedInterrupts( void );

	/*
	* Interrupt handlers used by the kernel itself. These are executed from the
	* simulated interrupt handler thread.
	*/
	static uint32_t prvProcessYieldInterrupt( void );
	static uint32_t prvProcessTickInterrupt( void );

	/*
	* Called when the process exits to let Windows know the high timer resolution
	* is no longer required.
	*/
	static BOOL WINAPI prvEndProcess( DWORD dwCtrlType );

	/-----------------------------------------------------------/

	/* The WIN32 simulator runs each task in a thread. The context switching is
	managed by the threads, so the task stack does not have to be managed directly,
	although the task stack is still used to hold an xThreadState structure this is
	the only thing it will ever hold. The structure indirectly maps the task handle
	to a thread handle. */
	typedef struct
	{
	/* Handle of the thread that executes the task. */
	void *pvThread;

	} xThreadState;

	/* Simulated interrupts waiting to be processed. This is a bit mask where each
	bit represents one interrupt, so a maximum of 32 interrupts can be simulated. */
	static volatile uint32_t ulPendingInterrupts = 0UL;

	/* An event used to inform the simulated interrupt processing thread (a high
	priority thread that simulated interrupt processing) that an interrupt is
	pending. */
	static void *pvInterruptEvent = NULL;

	/* Mutex used to protect all the simulated interrupt variables that are accessed
	by multiple threads. */
	static void *pvInterruptEventMutex = NULL;

	/* The critical nesting count for the currently executing task. This is
	initialised to a non-zero value so interrupts do not become enabled during
	the initialisation phase. As each task has its own critical nesting value
	ulCriticalNesting will get set to zero when the first task runs. This
	initialisation is probably not critical in this simulated environment as the
	simulated interrupt handlers do not get created until the FreeRTOS scheduler is
	started anyway. */
	static uint32_t ulCriticalNesting = 9999UL;

	/* Handlers for all the simulated software interrupts. The first two positions
	are used for the Yield and Tick interrupts so are handled slightly differently,
	all the other interrupts can be user defined. */
	static uint32_t (*ulIsrHandler[ portMAX_INTERRUPTS ])( void ) = { 0 };

	/* Pointer to the TCB of the currently executing task. */
	extern void *pxCurrentTCB;

	/* Used to ensure nothing is processed during the startup sequence. */
	static BaseType_t xPortRunning = pdFALSE;

	/-----------------------------------------------------------/

	static DWORD WINAPI prvSimulatedPeripheralTimer( LPVOID lpParameter )
	{
	TickType_t xMinimumWindowsBlockTime;
	TIMECAPS xTimeCaps;

	/* Set the timer resolution to the maximum possible. */
	if( timeGetDevCaps( &xTimeCaps, sizeof( xTimeCaps ) ) == MMSYSERR_NOERROR )
	{
	xMinimumWindowsBlockTime = ( TickType_t ) xTimeCaps.wPeriodMin;
	timeBeginPeriod( xTimeCaps.wPeriodMin );

	/* Register an exit handler so the timeBeginPeriod() function can be
	matched with a timeEndPeriod() when the application exits. */
	SetConsoleCtrlHandler( prvEndProcess, TRUE );
	}
	else
	{
	xMinimumWindowsBlockTime = ( TickType_t ) 20;
	}

	/* Just to prevent compiler warnings. */
	( void ) lpParameter;

	for(;;)
	{
	/* Wait until the timer expires and we can access the simulated interrupt
	variables. NOTE this is not a 'real time' way of generating tick
	events as the next wake time should be relative to the previous wake
	time, not the time that Sleep() is called. It is done this way to
	prevent overruns in this very non real time simulated/emulated
	environment. */
	if( portTICK_PERIOD_MS < xMinimumWindowsBlockTime )
	{
	Sleep( xMinimumWindowsBlockTime );
	}
	else
	{
	Sleep( portTICK_PERIOD_MS );
	}

	configASSERT( xPortRunning );

	WaitForSingleObject( pvInterruptEventMutex, INFINITE );

	/* The timer has expired, generate the simulated tick event. */
	ulPendingInterrupts \|= ( 1 << portINTERRUPT_TICK );

	/* The interrupt is now pending - notify the simulated interrupt
	handler thread. */
	if( ulCriticalNesting == 0 )
	{
	SetEvent( pvInterruptEvent );
	}

	/* Give back the mutex so the simulated interrupt handler unblocks
	and can access the interrupt handler variables. */
	ReleaseMutex( pvInterruptEventMutex );
	}

	#ifdef __GNUC__
	/* Should never reach here - MingW complains if you leave this line out,
	MSVC complains if you put it in. */
	return 0;
	#endif
	}
	/-----------------------------------------------------------/

	static BOOL WINAPI prvEndProcess( DWORD dwCtrlType )
	{
	TIMECAPS xTimeCaps;

	( void ) dwCtrlType;

	if( timeGetDevCaps( &xTimeCaps, sizeof( xTimeCaps ) ) == MMSYSERR_NOERROR )
	{
	/* Match the call to timeBeginPeriod( xTimeCaps.wPeriodMin ) made when
	the process started with a timeEndPeriod() as the process exits. */
	timeEndPeriod( xTimeCaps.wPeriodMin );
	}

	return pdPASS;
	}
	/-----------------------------------------------------------/

	StackType_t pxPortInitialiseStack( StackType_t pxTopOfStack, TaskFunction_t pxCode, void *pvParameters )
	{
	xThreadState *pxThreadState = NULL;
	int8_t pcTopOfStack = ( int8_t ) pxTopOfStack;

	/* In this simulated case a stack is not initialised, but instead a thread
	is created that will execute the task being created. The thread handles
	the context switching itself. The xThreadState object is placed onto
	the stack that was created for the task - so the stack buffer is still
	used, just not in the conventional way. It will not be used for anything
	other than holding this structure. */
	pxThreadState = ( xThreadState * ) ( pcTopOfStack - sizeof( xThreadState ) );

	/* Create the thread itself. */
	pxThreadState->pvThread = CreateThread( NULL, 0, ( LPTHREAD_START_ROUTINE ) pxCode, pvParameters, CREATE_SUSPENDED, NULL );
	configASSERT( pxThreadState->pvThread );
	SetThreadAffinityMask( pxThreadState->pvThread, 0x01 );
	SetThreadPriorityBoost( pxThreadState->pvThread, TRUE );
	SetThreadPriority( pxThreadState->pvThread, THREAD_PRIORITY_IDLE );

	return ( StackType_t * ) pxThreadState;
	}
	/-----------------------------------------------------------/

	BaseType_t xPortStartScheduler( void )
	{
	void *pvHandle;
	int32_t lSuccess = pdPASS;
	xThreadState *pxThreadState;

	/* Install the interrupt handlers used by the scheduler itself. */
	vPortSetInterruptHandler( portINTERRUPT_YIELD, prvProcessYieldInterrupt );
	vPortSetInterruptHandler( portINTERRUPT_TICK, prvProcessTickInterrupt );

	/* Create the events and mutexes that are used to synchronise all the
	threads. */
	pvInterruptEventMutex = CreateMutex( NULL, FALSE, NULL );
	pvInterruptEvent = CreateEvent( NULL, FALSE, FALSE, NULL );

	if( ( pvInterruptEventMutex == NULL ) \|\| ( pvInterruptEvent == NULL ) )
	{
	lSuccess = pdFAIL;
	}

	/* Set the priority of this thread such that it is above the priority of
	the threads that run tasks. This higher priority is required to ensure
	simulated interrupts take priority over tasks. */
	pvHandle = GetCurrentThread();
	if( pvHandle == NULL )
	{
	lSuccess = pdFAIL;
	}

	if( lSuccess == pdPASS )
	{
	if( SetThreadPriority( pvHandle, THREAD_PRIORITY_NORMAL ) == 0 )
	{
	lSuccess = pdFAIL;
	}
	SetThreadPriorityBoost( pvHandle, TRUE );
	SetThreadAffinityMask( pvHandle, 0x01 );
	}

	if( lSuccess == pdPASS )
	{
	/* Start the thread that simulates the timer peripheral to generate
	tick interrupts. The priority is set below that of the simulated
	interrupt handler so the interrupt event mutex is used for the
	handshake / overrun protection. */
	pvHandle = CreateThread( NULL, 0, prvSimulatedPeripheralTimer, NULL, 0, NULL );
	if( pvHandle != NULL )
	{
	SetThreadPriority( pvHandle, THREAD_PRIORITY_BELOW_NORMAL );
	SetThreadPriorityBoost( pvHandle, TRUE );
	SetThreadAffinityMask( pvHandle, 0x01 );
	}

	/* Start the highest priority task by obtaining its associated thread
	state structure, in which is stored the thread handle. */
	pxThreadState = ( xThreadState * ) ( ( uint32_t ) pxCurrentTCB );
	ulCriticalNesting = portNO_CRITICAL_NESTING;

	/* Bump up the priority of the thread that is going to run, in the
	hope that this will assist in getting the Windows thread scheduler to
	behave as an embedded engineer might expect. */
	ResumeThread( pxThreadState->pvThread );

	/* Handle all simulated interrupts - including yield requests and
	simulated ticks. */
	prvProcessSimulatedInterrupts();
	}

	/* Would not expect to return from prvProcessSimulatedInterrupts(), so should
	not get here. */
	return 0;
	}
	/-----------------------------------------------------------/

	static uint32_t prvProcessYieldInterrupt( void )
	{
	return pdTRUE;
	}
	/-----------------------------------------------------------/

	static uint32_t prvProcessTickInterrupt( void )
	{
	uint32_t ulSwitchRequired;

	/* Process the tick itself. */
	configASSERT( xPortRunning );
	ulSwitchRequired = ( uint32_t ) xTaskIncrementTick();

	return ulSwitchRequired;
	}
	/-----------------------------------------------------------/

	static void prvProcessSimulatedInterrupts( void )
	{
	uint32_t ulSwitchRequired, i;
	xThreadState *pxThreadState;
	void *pvObjectList[ 2 ];

	/* Going to block on the mutex that ensured exclusive access to the simulated
	interrupt objects, and the event that signals that a simulated interrupt
	should be processed. */
	pvObjectList[ 0 ] = pvInterruptEventMutex;
	pvObjectList[ 1 ] = pvInterruptEvent;

	/* Create a pending tick to ensure the first task is started as soon as
	this thread pends. */
	ulPendingInterrupts \|= ( 1 << portINTERRUPT_TICK );
	SetEvent( pvInterruptEvent );

	xPortRunning = pdTRUE;

	for(;;)
	{
	WaitForMultipleObjects( sizeof( pvObjectList ) / sizeof( void * ), pvObjectList, TRUE, INFINITE );

	/* Used to indicate whether the simulated interrupt processing has
	necessitated a context switch to another task/thread. */
	ulSwitchRequired = pdFALSE;

	/* For each interrupt we are interested in processing, each of which is
	represented by a bit in the 32bit ulPendingInterrupts variable. */
	for( i = 0; i < portMAX_INTERRUPTS; i++ )
	{
	/* Is the simulated interrupt pending? */
	if( ulPendingInterrupts & ( 1UL << i ) )
	{
	/* Is a handler installed? */
	if( ulIsrHandler[ i ] != NULL )
	{
	/* Run the actual handler. */
	if( ulIsrHandler[ i ]() != pdFALSE )
	{
	ulSwitchRequired \|= ( 1 << i );
	}
	}

	/* Clear the interrupt pending bit. */
	ulPendingInterrupts &= ~( 1UL << i );
	}
	}

	if( ulSwitchRequired != pdFALSE )
	{
	void *pvOldCurrentTCB;

	pvOldCurrentTCB = pxCurrentTCB;

	/* Select the next task to run. */
	vTaskSwitchContext();

	/* If the task selected to enter the running state is not the task
	that is already in the running state. */
	if( pvOldCurrentTCB != pxCurrentTCB )
	{
	/* Suspend the old thread. */
	pxThreadState = ( xThreadState ) ( ( uint32_t * ) pvOldCurrentTCB );
	SuspendThread( pxThreadState->pvThread );

	/* Obtain the state of the task now selected to enter the
	Running state. */
	pxThreadState = ( xThreadState * ) ( ( uint32_t ) pxCurrentTCB );
	ResumeThread( pxThreadState->pvThread );
	}
	}

	ReleaseMutex( pvInterruptEventMutex );
	}
	}
	/-----------------------------------------------------------/

	void vPortDeleteThread( void *pvTaskToDelete )
	{
	xThreadState *pxThreadState;
	uint32_t ulErrorCode;

	/* Remove compiler warnings if configASSERT() is not defined. */
	( void ) ulErrorCode;

	/* Find the handle of the thread being deleted. */
	pxThreadState = ( xThreadState * ) ( ( uint32_t ) pvTaskToDelete );

	/* Check that the thread is still valid, it might have been closed by
	vPortCloseRunningThread() - which will be the case if the task associated
	with the thread originally deleted itself rather than being deleted by a
	different task. */
	if( pxThreadState->pvThread != NULL )
	{
	WaitForSingleObject( pvInterruptEventMutex, INFINITE );

	ulErrorCode = TerminateThread( pxThreadState->pvThread, 0 );
	configASSERT( ulErrorCode );

	ulErrorCode = CloseHandle( pxThreadState->pvThread );
	configASSERT( ulErrorCode );

	ReleaseMutex( pvInterruptEventMutex );
	}
	}
	/-----------------------------------------------------------/

	void vPortCloseRunningThread( void pvTaskToDelete, volatile BaseType_t pxPendYield )
	{
	xThreadState *pxThreadState;
	void *pvThread;
	uint32_t ulErrorCode;

	/* Remove compiler warnings if configASSERT() is not defined. */
	( void ) ulErrorCode;

	/* Find the handle of the thread being deleted. */
	pxThreadState = ( xThreadState * ) ( ( uint32_t ) pvTaskToDelete );
	pvThread = pxThreadState->pvThread;

	/* Raise the Windows priority of the thread to ensure the FreeRTOS scheduler
	does not run and swap it out before it is closed. If that were to happen
	the thread would never run again and effectively be a thread handle and
	memory leak. */
	SetThreadPriority( pvThread, THREAD_PRIORITY_ABOVE_NORMAL );

	/* This function will not return, therefore a yield is set as pending to
	ensure a context switch occurs away from this thread on the next tick. */
	*pxPendYield = pdTRUE;

	/* Mark the thread associated with this task as invalid so
	vPortDeleteThread() does not try to terminate it. */
	pxThreadState->pvThread = NULL;

	/* Close the thread. */
	ulErrorCode = CloseHandle( pvThread );
	configASSERT( ulErrorCode );

	ExitThread( 0 );
	}
	/-----------------------------------------------------------/

	void vPortEndScheduler( void )
	{
	/* This function IS NOT TESTED! */
	TerminateProcess( GetCurrentProcess(), 0 );
	}
	/-----------------------------------------------------------/

	void vPortGenerateSimulatedInterrupt( uint32_t ulInterruptNumber )
	{
	configASSERT( xPortRunning );

	if( ( ulInterruptNumber < portMAX_INTERRUPTS ) && ( pvInterruptEventMutex != NULL ) )
	{
	/* Yield interrupts are processed even when critical nesting is non-zero. */
	WaitForSingleObject( pvInterruptEventMutex, INFINITE );
	ulPendingInterrupts \|= ( 1 << ulInterruptNumber );

	/* The simulated interrupt is now held pending, but don't actually process it
	yet if this call is within a critical section. It is possible for this to
	be in a critical section as calls to wait for mutexes are accumulative. */
	if( ulCriticalNesting == 0 )
	{
	SetEvent( pvInterruptEvent );
	}

	ReleaseMutex( pvInterruptEventMutex );
	}
	}
	/-----------------------------------------------------------/

	void vPortSetInterruptHandler( uint32_t ulInterruptNumber, uint32_t (*pvHandler)( void ) )
	{
	if( ulInterruptNumber < portMAX_INTERRUPTS )
	{
	if( pvInterruptEventMutex != NULL )
	{
	WaitForSingleObject( pvInterruptEventMutex, INFINITE );
	ulIsrHandler[ ulInterruptNumber ] = pvHandler;
	ReleaseMutex( pvInterruptEventMutex );
	}
	else
	{
	ulIsrHandler[ ulInterruptNumber ] = pvHandler;
	}
	}
	}
	/-----------------------------------------------------------/

	void vPortEnterCritical( void )
	{
	if( xPortRunning == pdTRUE )
	{
	/* The interrupt event mutex is held for the entire critical section,
	effectively disabling (simulated) interrupts. */
	WaitForSingleObject( pvInterruptEventMutex, INFINITE );
	ulCriticalNesting++;
	}
	else
	{
	ulCriticalNesting++;
	}
	}
	/-----------------------------------------------------------/

	void vPortExitCritical( void )
	{
	int32_t lMutexNeedsReleasing;

	/* The interrupt event mutex should already be held by this thread as it was
	obtained on entry to the critical section. */

	lMutexNeedsReleasing = pdTRUE;

	if( ulCriticalNesting > portNO_CRITICAL_NESTING )
	{
	if( ulCriticalNesting == ( portNO_CRITICAL_NESTING + 1 ) )
	{
	ulCriticalNesting--;

	/* Were any interrupts set to pending while interrupts were
	(simulated) disabled? */
	if( ulPendingInterrupts != 0UL )
	{
	configASSERT( xPortRunning );
	SetEvent( pvInterruptEvent );

	/* Mutex will be released now, so does not require releasing
	on function exit. */
	lMutexNeedsReleasing = pdFALSE;
	ReleaseMutex( pvInterruptEventMutex );
	}
	}
	else
	{
	/* Tick interrupts will still not be processed as the critical
	nesting depth will not be zero. */
	ulCriticalNesting--;
	}
	}

	if( pvInterruptEventMutex != NULL )
	{
	if( lMutexNeedsReleasing == pdTRUE )
	{
	configASSERT( xPortRunning );
	ReleaseMutex( pvInterruptEventMutex );
	}
	}
	}
	/-----------------------------------------------------------/