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/*

    FreeRTOS V6.1.1 - Copyright (C) 2011 Real Time Engineers Ltd.

    ***************************************************************************

    *                                                                         *

    * If you are:                                                             *

    *                                                                         *

    *    + New to FreeRTOS,                                                   *

    *    + Wanting to learn FreeRTOS or multitasking in general quickly       *

    *    + Looking for basic training,                                        *

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    *                                                                         *

    * then take a look at the FreeRTOS books - available as PDF or paperback  *

    *                                                                         *

    *        "Using the FreeRTOS Real Time Kernel - a Practical Guide"        *

    *                  http://www.FreeRTOS.org/Documentation                  *

    *                                                                         *

    * A pdf reference manual is also available.  Both are usually delivered   *

    * to your inbox within 20 minutes to two hours when purchased between 8am *

    * and 8pm GMT (although please allow up to 24 hours in case of            *

    * exceptional circumstances).  Thank you for your support!                *

    *                                                                         *

    ***************************************************************************

    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 exception 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.  See the GNU General Public License for

    more details. You should have received a copy of the GNU General Public

    License and the FreeRTOS license exception along with FreeRTOS; if not it

    can be viewed here: http://www.freertos.org/a00114.html and also obtained

    by writing to Richard Barry, contact details for whom are available on the

    FreeRTOS WEB site.

    1 tab == 4 spaces!

    http://www.FreeRTOS.org - Documentation, latest information, license and

    contact details.

    http://www.SafeRTOS.com - A version that is certified for use in safety

    critical systems.

    http://www.OpenRTOS.com - Commercial support, development, porting,

    licensing and training services.

*/

/* Scheduler includes. */

#include "FreeRTOS.h"

#include "task.h"

#include <stdio.h>

#define portMAX_INTERRUPTS                              ( ( unsigned long ) sizeof( unsigned long ) * 8UL ) /* The number of bits in an unsigned long. */

#define portNO_CRITICAL_NESTING                 ( ( unsigned long ) 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 unsigned long prvProcessDeleteThreadInterrupt( void );

static unsigned long prvProcessYieldInterrupt( void );

static unsigned long prvProcessTickInterrupt( void );

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

/* 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 unsigned long 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 unsigned long 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 unsigned long (*ulIsrHandler[ portMAX_INTERRUPTS ])( void ) = { 0 };

/* Pointer to the TCB of the currently executing task. */

extern void *pxCurrentTCB;

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

static DWORD WINAPI prvSimulatedPeripheralTimer( LPVOID lpParameter )

{

        /* 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. */

                Sleep( portTICK_RATE_MS );

                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. */

                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

}

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

portSTACK_TYPE *pxPortInitialiseStack( portSTACK_TYPE *pxTopOfStack, pdTASK_CODE pxCode, void *pvParameters )

{

xThreadState *pxThreadState = NULL;

        /* 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 * ) ( pxTopOfStack - sizeof( xThreadState ) );

        /* Create the thread itself. */

        pxThreadState->pvThread = CreateThread( NULL, 0, ( LPTHREAD_START_ROUTINE ) pxCode, pvParameters, CREATE_SUSPENDED, NULL );

        SetThreadAffinityMask( pxThreadState->pvThread, 0x01 );

        SetThreadPriorityBoost( pxThreadState->pvThread, TRUE );

        SetThreadPriority( pxThreadState->pvThread, THREAD_PRIORITY_IDLE );

        return ( portSTACK_TYPE * ) pxThreadState;

}

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

portBASE_TYPE xPortStartScheduler( void )

{

void *pvHandle;

long lSuccess = pdPASS;

xThreadState *pxThreadState;

        /* Install the interrupt handlers used by the scheduler itself. */

        vPortSetInterruptHandler( portINTERRUPT_YIELD, prvProcessYieldInterrupt );

        vPortSetInterruptHandler( portINTERRUPT_TICK, prvProcessTickInterrupt );

        vPortSetInterruptHandler( portINTERRUPT_DELETE_THREAD, prvProcessDeleteThreadInterrupt );

        /* 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 * ) *( ( unsigned long * ) pxCurrentTCB );

                ulCriticalNesting = portNO_CRITICAL_NESTING;

                /* Bump up the priority of the thread that is going to run, in the

                hope that this will asist 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 unsigned long prvProcessDeleteThreadInterrupt( void )

{

        return pdTRUE;

}

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

static unsigned long prvProcessYieldInterrupt( void )

{

        return pdTRUE;

}

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

static unsigned long prvProcessTickInterrupt( void )

{

unsigned long ulSwitchRequired;

        /* Process the tick itself. */

        vTaskIncrementTick();

        #if( configUSE_PREEMPTION != 0 )

        {

                /* A context switch is only automatically performed from the tick

                interrupt if the pre-emptive scheduler is being used. */

                ulSwitchRequired = pdTRUE;

        }

        #else

        {

                ulSwitchRequired = pdFALSE;

        }

        #endif

        return ulSwitchRequired;

}

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

static void prvProcessSimulatedInterrupts( void )

{

unsigned long 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;

        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 *) *( ( unsigned long * ) pvOldCurrentTCB );

                                if( ( ulSwitchRequired & ( 1 << portINTERRUPT_DELETE_THREAD ) ) != pdFALSE )

                                {

                                        TerminateThread( pxThreadState->pvThread, 0 );

                                }

                                else

                                {

                                        SuspendThread( pxThreadState->pvThread );

                                }

                                /* Obtain the state of the task now selected to enter the

                                Running state. */

                                pxThreadState = ( xThreadState * ) ( *( unsigned long *) pxCurrentTCB );

                                ResumeThread( pxThreadState->pvThread );

                        }

                }

                ReleaseMutex( pvInterruptEventMutex );

        }

}

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

void vPortDeleteThread( void *pvTaskToDelete )

{

xThreadState *pxThreadState;

        if( pvTaskToDelete == pxCurrentTCB )

        {

                /* The task is deleting itself, and so the thread that is running now

                is also to be deleted.  This has to be deferred until this thread is

                no longer running, so its done in the simulated interrupt handler thread. */

                vPortGenerateSimulatedInterrupt( portINTERRUPT_DELETE_THREAD );

        }

        else

        {

                WaitForSingleObject( pvInterruptEventMutex, INFINITE );

                /* Find the handle of the thread being deleted. */

                pxThreadState = ( xThreadState * ) ( *( unsigned long *) pvTaskToDelete );

                TerminateThread( pxThreadState->pvThread, 0 );

                ReleaseMutex( pvInterruptEventMutex );

        }

}

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

void vPortEndScheduler( void )

{

        /* This function IS NOT TESTED! */

        TerminateProcess( GetCurrentProcess(), 0 );

}

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

void vPortGenerateSimulatedInterrupt( unsigned long ulInterruptNumber )

{

xThreadState *pxThreadState;

        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 )

                {

                        /* The event handler needs to know to signal the interrupt acknowledge event

                        the next time this task runs. */

                        pxThreadState = ( xThreadState * ) *( ( unsigned long * ) pxCurrentTCB );

                        SetEvent( pvInterruptEvent );

                }

                ReleaseMutex( pvInterruptEventMutex );

        }

}

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

void vPortSetInterruptHandler( unsigned long ulInterruptNumber, unsigned long (*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( xTaskGetSchedulerState() != taskSCHEDULER_NOT_STARTED )

        {

                /* The interrupt event mutex is held for the entire critical section,

                effectively disabling (simulated) interrupts. */

                WaitForSingleObject( pvInterruptEventMutex, INFINITE );

                ulCriticalNesting++;

        }

        else

        {

                ulCriticalNesting++;

        }

}

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

void vPortExitCritical( void )

{

xThreadState *pxThreadState;

long 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 )

                        {

                                SetEvent( pvInterruptEvent );

                                /* The event handler needs to know to signal the interrupt

                                acknowledge event the next time this task runs. */

                                pxThreadState = ( xThreadState * ) *( ( unsigned long * ) pxCurrentTCB );

                                /* 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( lMutexNeedsReleasing == pdTRUE )

        {

                ReleaseMutex( pvInterruptEventMutex );

        }

}

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