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/*
 * Demonstrates and tests mutexes being used from an interrupt.
 */


#include <stdlib.h>

/* Scheduler include files. */
#include "FreeRTOS.h"
#include "task.h"
#include "semphr.h"

/* Demo program include files. */
#include "IntSemTest.h"

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

/* The priorities of the test tasks. */
#define intsemMASTER_PRIORITY                   ( tskIDLE_PRIORITY )
#define intsemSLAVE_PRIORITY                    ( tskIDLE_PRIORITY + 1 )

/* The rate at which the tick hook will give the mutex. */
#define intsemINTERRUPT_MUTEX_GIVE_PERIOD_MS    ( 100 )

/* A block time of 0 means 'don't block'. */
#define intsemNO_BLOCK                          0

/* The maximum count value for the counting semaphore given from an
 * interrupt. */
#define intsemMAX_COUNT                         3

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

/*
 * The master is a task that receives a mutex that is given from an interrupt -
 * although generally mutexes should not be used given in interrupts (and
 * definitely never taken in an interrupt) there are some circumstances when it
 * may be desirable.
 *
 * The slave task is just used by the master task to force priority inheritance
 * on a mutex that is shared between the master and the slave - which is a
 * separate mutex to that given by the interrupt.
 */
static void vInterruptMutexSlaveTask( void * pvParameters );
static void vInterruptMutexMasterTask( void * pvParameters );

/*
 * A test whereby the master takes the shared and interrupt mutexes in that
 * order, then gives them back in the same order, ensuring the priority
 * inheritance is behaving as expected at each step.
 */
static void prvTakeAndGiveInTheSameOrder( void );

/*
 * A test whereby the master takes the shared and interrupt mutexes in that
 * order, then gives them back in the opposite order to which they were taken,
 * ensuring the priority inheritance is behaving as expected at each step.
 */
static void prvTakeAndGiveInTheOppositeOrder( void );

/*
 * A simple task that interacts with an interrupt using a counting semaphore,
 * primarily for code coverage purposes.
 */
static void vInterruptCountingSemaphoreTask( void * pvParameters );

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

/* Flag that will be latched to pdTRUE should any unexpected behaviour be
 * detected in any of the tasks. */
static volatile BaseType_t xErrorDetected = pdFALSE;

/* Counters that are incremented on each cycle of a test.  This is used to
 * detect a stalled task - a test that is no longer running. */
static volatile uint32_t ulMasterLoops = 0, ulCountingSemaphoreLoops = 0;

/* Handles of the test tasks that must be accessed from other test tasks. */
static TaskHandle_t xSlaveHandle;

/* A mutex which is given from an interrupt - although generally mutexes should
 * not be used given in interrupts (and definitely never taken in an interrupt)
 * there are some circumstances when it may be desirable. */
static SemaphoreHandle_t xISRMutex = NULL;

/* A counting semaphore which is given from an interrupt. */
static SemaphoreHandle_t xISRCountingSemaphore = NULL;

/* A mutex which is shared between the master and slave tasks - the master
 * does both sharing of this mutex with the slave and receiving a mutex from the
 * interrupt. */
static SemaphoreHandle_t xMasterSlaveMutex = NULL;

/* Flag that allows the master task to control when the interrupt gives or does
 * not give the mutex.  There is no mutual exclusion on this variable, but this is
 * only test code and it should be fine in the 32=bit test environment. */
static BaseType_t xOkToGiveMutex = pdFALSE, xOkToGiveCountingSemaphore = pdFALSE;

/* Used to coordinate timing between tasks and the interrupt. */
const TickType_t xInterruptGivePeriod = pdMS_TO_TICKS( intsemINTERRUPT_MUTEX_GIVE_PERIOD_MS );

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

void vStartInterruptSemaphoreTasks( void )
{
    /* Create the semaphores that are given from an interrupt. */
    xISRMutex = xSemaphoreCreateMutex();
    configASSERT( xISRMutex );
    xISRCountingSemaphore = xSemaphoreCreateCounting( intsemMAX_COUNT, 0 );
    configASSERT( xISRCountingSemaphore );

    /* Create the mutex that is shared between the master and slave tasks (the
     * master receives a mutex from an interrupt and shares a mutex with the
     * slave. */
    xMasterSlaveMutex = xSemaphoreCreateMutex();
    configASSERT( xMasterSlaveMutex );

    /* Create the tasks that share mutexes between then and with interrupts. */
    xTaskCreate( vInterruptMutexSlaveTask, "IntMuS", configMINIMAL_STACK_SIZE, NULL, intsemSLAVE_PRIORITY, &xSlaveHandle );
    xTaskCreate( vInterruptMutexMasterTask, "IntMuM", configMINIMAL_STACK_SIZE, NULL, intsemMASTER_PRIORITY, NULL );

    /* Create the task that blocks on the counting semaphore. */
    xTaskCreate( vInterruptCountingSemaphoreTask, "IntCnt", configMINIMAL_STACK_SIZE, NULL, tskIDLE_PRIORITY, NULL );
}
/*-----------------------------------------------------------*/

static void vInterruptMutexMasterTask( void * pvParameters )
{
    /* Just to avoid compiler warnings. */
    ( void ) pvParameters;

    for( ; ; )
    {
        prvTakeAndGiveInTheSameOrder();

        /* Ensure not to starve out other tests. */
        ulMasterLoops++;
        vTaskDelay( intsemINTERRUPT_MUTEX_GIVE_PERIOD_MS );

        prvTakeAndGiveInTheOppositeOrder();

        /* Ensure not to starve out other tests. */
        ulMasterLoops++;
        vTaskDelay( intsemINTERRUPT_MUTEX_GIVE_PERIOD_MS );
    }
}
/*-----------------------------------------------------------*/

static void prvTakeAndGiveInTheSameOrder( void )
{
    /* Ensure the slave is suspended, and that this task is running at the
     * lower priority as expected as the start conditions. */
    #if ( INCLUDE_eTaskGetState == 1 )
        {
            configASSERT( eTaskGetState( xSlaveHandle ) == eSuspended );
        }
    #endif /* INCLUDE_eTaskGetState */

    if( uxTaskPriorityGet( NULL ) != intsemMASTER_PRIORITY )
    {
        xErrorDetected = pdTRUE;
    }

    /* Take the semaphore that is shared with the slave. */
    if( xSemaphoreTake( xMasterSlaveMutex, intsemNO_BLOCK ) != pdPASS )
    {
        xErrorDetected = pdTRUE;
    }

    /* This task now has the mutex.  Unsuspend the slave so it too
     * attempts to take the mutex. */
    vTaskResume( xSlaveHandle );

    /* The slave has the higher priority so should now have executed and
     * blocked on the semaphore. */
    #if ( INCLUDE_eTaskGetState == 1 )
        {
            configASSERT( eTaskGetState( xSlaveHandle ) == eBlocked );
        }
    #endif /* INCLUDE_eTaskGetState */

    /* This task should now have inherited the priority of the slave
     * task. */
    if( uxTaskPriorityGet( NULL ) != intsemSLAVE_PRIORITY )
    {
        xErrorDetected = pdTRUE;
    }

    /* Now wait a little longer than the time between ISR gives to also
     * obtain the ISR mutex. */
    xOkToGiveMutex = pdTRUE;

    if( xSemaphoreTake( xISRMutex, ( xInterruptGivePeriod * 2 ) ) != pdPASS )
    {
        xErrorDetected = pdTRUE;
    }

    xOkToGiveMutex = pdFALSE;

    /* Attempting to take again immediately should fail as the mutex is
     * already held. */
    if( xSemaphoreTake( xISRMutex, intsemNO_BLOCK ) != pdFAIL )
    {
        xErrorDetected = pdTRUE;
    }

    /* Should still be at the priority of the slave task. */
    if( uxTaskPriorityGet( NULL ) != intsemSLAVE_PRIORITY )
    {
        xErrorDetected = pdTRUE;
    }

    /* Give back the ISR semaphore to ensure the priority is not
     * disinherited as the shared mutex (which the higher priority task is
     * attempting to obtain) is still held. */
    if( xSemaphoreGive( xISRMutex ) != pdPASS )
    {
        xErrorDetected = pdTRUE;
    }

    if( uxTaskPriorityGet( NULL ) != intsemSLAVE_PRIORITY )
    {
        xErrorDetected = pdTRUE;
    }

    /* Finally give back the shared mutex.  This time the higher priority
     * task should run before this task runs again - so this task should have
     * disinherited the priority and the higher priority task should be in the
     * suspended state again. */
    if( xSemaphoreGive( xMasterSlaveMutex ) != pdPASS )
    {
        xErrorDetected = pdTRUE;
    }

    if( uxTaskPriorityGet( NULL ) != intsemMASTER_PRIORITY )
    {
        xErrorDetected = pdTRUE;
    }

    #if ( INCLUDE_eTaskGetState == 1 )
        {
            configASSERT( eTaskGetState( xSlaveHandle ) == eSuspended );
        }
    #endif /* INCLUDE_eTaskGetState */

    /* Reset the mutex ready for the next round. */
    xQueueReset( xISRMutex );
}
/*-----------------------------------------------------------*/

static void prvTakeAndGiveInTheOppositeOrder( void )
{
    /* Ensure the slave is suspended, and that this task is running at the
     * lower priority as expected as the start conditions. */
    #if ( INCLUDE_eTaskGetState == 1 )
        {
            configASSERT( eTaskGetState( xSlaveHandle ) == eSuspended );
        }
    #endif /* INCLUDE_eTaskGetState */

    if( uxTaskPriorityGet( NULL ) != intsemMASTER_PRIORITY )
    {
        xErrorDetected = pdTRUE;
    }

    /* Take the semaphore that is shared with the slave. */
    if( xSemaphoreTake( xMasterSlaveMutex, intsemNO_BLOCK ) != pdPASS )
    {
        xErrorDetected = pdTRUE;
    }

    /* This task now has the mutex.  Unsuspend the slave so it too
     * attempts to take the mutex. */
    vTaskResume( xSlaveHandle );

    /* The slave has the higher priority so should now have executed and
     * blocked on the semaphore. */
    #if ( INCLUDE_eTaskGetState == 1 )
        {
            configASSERT( eTaskGetState( xSlaveHandle ) == eBlocked );
        }
    #endif /* INCLUDE_eTaskGetState */

    /* This task should now have inherited the priority of the slave
     * task. */
    if( uxTaskPriorityGet( NULL ) != intsemSLAVE_PRIORITY )
    {
        xErrorDetected = pdTRUE;
    }

    /* Now wait a little longer than the time between ISR gives to also
     * obtain the ISR mutex. */
    xOkToGiveMutex = pdTRUE;

    if( xSemaphoreTake( xISRMutex, ( xInterruptGivePeriod * 2 ) ) != pdPASS )
    {
        xErrorDetected = pdTRUE;
    }

    xOkToGiveMutex = pdFALSE;

    /* Attempting to take again immediately should fail as the mutex is
     * already held. */
    if( xSemaphoreTake( xISRMutex, intsemNO_BLOCK ) != pdFAIL )
    {
        xErrorDetected = pdTRUE;
    }

    /* Should still be at the priority of the slave task. */
    if( uxTaskPriorityGet( NULL ) != intsemSLAVE_PRIORITY )
    {
        xErrorDetected = pdTRUE;
    }

    /* Give back the shared semaphore to ensure the priority is not disinherited
     * as the ISR mutex is still held.  The higher priority slave task should run
     * before this task runs again. */
    if( xSemaphoreGive( xMasterSlaveMutex ) != pdPASS )
    {
        xErrorDetected = pdTRUE;
    }

    /* Should still be at the priority of the slave task as this task still
     * holds one semaphore (this is a simplification in the priority inheritance
     * mechanism. */
    if( uxTaskPriorityGet( NULL ) != intsemSLAVE_PRIORITY )
    {
        xErrorDetected = pdTRUE;
    }

    /* Give back the ISR semaphore, which should result in the priority being
     * disinherited as it was the last mutex held. */
    if( xSemaphoreGive( xISRMutex ) != pdPASS )
    {
        xErrorDetected = pdTRUE;
    }

    if( uxTaskPriorityGet( NULL ) != intsemMASTER_PRIORITY )
    {
        xErrorDetected = pdTRUE;
    }

    /* Reset the mutex ready for the next round. */
    xQueueReset( xISRMutex );
}
/*-----------------------------------------------------------*/

static void vInterruptMutexSlaveTask( void * pvParameters )
{
    /* Just to avoid compiler warnings. */
    ( void ) pvParameters;

    for( ; ; )
    {
        /* This task starts by suspending itself so when it executes can be
         * controlled by the master task. */
        vTaskSuspend( NULL );

        /* This task will execute when the master task already holds the mutex.
         * Attempting to take the mutex will place this task in the Blocked
         * state. */
        if( xSemaphoreTake( xMasterSlaveMutex, portMAX_DELAY ) != pdPASS )
        {
            xErrorDetected = pdTRUE;
        }

        if( xSemaphoreGive( xMasterSlaveMutex ) != pdPASS )
        {
            xErrorDetected = pdTRUE;
        }
    }
}
/*-----------------------------------------------------------*/

static void vInterruptCountingSemaphoreTask( void * pvParameters )
{
    BaseType_t xCount;
    const TickType_t xDelay = pdMS_TO_TICKS( intsemINTERRUPT_MUTEX_GIVE_PERIOD_MS ) * ( intsemMAX_COUNT + 1 );

    ( void ) pvParameters;

    for( ; ; )
    {
        /* Expect to start with the counting semaphore empty. */
        if( uxQueueMessagesWaiting( ( QueueHandle_t ) xISRCountingSemaphore ) != 0 )
        {
            xErrorDetected = pdTRUE;
        }

        /* Wait until it is expected that the interrupt will have filled the
         * counting semaphore. */
        xOkToGiveCountingSemaphore = pdTRUE;
        vTaskDelay( xDelay );
        xOkToGiveCountingSemaphore = pdFALSE;

        /* Now it is expected that the counting semaphore is full. */
        if( uxQueueMessagesWaiting( ( QueueHandle_t ) xISRCountingSemaphore ) != intsemMAX_COUNT )
        {
            xErrorDetected = pdTRUE;
        }

        if( uxQueueSpacesAvailable( ( QueueHandle_t ) xISRCountingSemaphore ) != 0 )
        {
            xErrorDetected = pdTRUE;
        }

        ulCountingSemaphoreLoops++;

        /* Expect to be able to take the counting semaphore intsemMAX_COUNT
         * times.  A block time of 0 is used as the semaphore should already be
         * there. */
        xCount = 0;

        while( xSemaphoreTake( xISRCountingSemaphore, 0 ) == pdPASS )
        {
            xCount++;
        }

        if( xCount != intsemMAX_COUNT )
        {
            xErrorDetected = pdTRUE;
        }

        /* Now raise the priority of this task so it runs immediately that the
         * semaphore is given from the interrupt. */
        vTaskPrioritySet( NULL, configMAX_PRIORITIES - 1 );

        /* Block to wait for the semaphore to be given from the interrupt. */
        xOkToGiveCountingSemaphore = pdTRUE;
        xSemaphoreTake( xISRCountingSemaphore, portMAX_DELAY );
        xSemaphoreTake( xISRCountingSemaphore, portMAX_DELAY );
        xOkToGiveCountingSemaphore = pdFALSE;

        /* Reset the priority so as not to disturbe other tests too much. */
        vTaskPrioritySet( NULL, tskIDLE_PRIORITY );

        ulCountingSemaphoreLoops++;
    }
}
/*-----------------------------------------------------------*/

void vInterruptSemaphorePeriodicTest( void )
{
    static TickType_t xLastGiveTime = 0;
    BaseType_t xHigherPriorityTaskWoken = pdFALSE;
    TickType_t xTimeNow;

    /* No mutual exclusion on xOkToGiveMutex, but this is only test code (and
    * only executed on a 32-bit architecture) so ignore that in this case. */
    xTimeNow = xTaskGetTickCountFromISR();

    if( ( ( TickType_t ) ( xTimeNow - xLastGiveTime ) ) >= pdMS_TO_TICKS( intsemINTERRUPT_MUTEX_GIVE_PERIOD_MS ) )
    {
        configASSERT( xISRMutex );

        if( xOkToGiveMutex != pdFALSE )
        {
            /* Null is used as the second parameter in this give, and non-NULL
             * in the other gives for code coverage reasons. */
            xSemaphoreGiveFromISR( xISRMutex, NULL );

            /* Second give attempt should fail. */
            configASSERT( xSemaphoreGiveFromISR( xISRMutex, &xHigherPriorityTaskWoken ) == pdFAIL );
        }

        if( xOkToGiveCountingSemaphore != pdFALSE )
        {
            xSemaphoreGiveFromISR( xISRCountingSemaphore, &xHigherPriorityTaskWoken );
        }

        xLastGiveTime = xTimeNow;
    }

    /* Remove compiler warnings about the value being set but not used. */
    ( void ) xHigherPriorityTaskWoken;
}
/*-----------------------------------------------------------*/

/* This is called to check that all the created tasks are still running. */
BaseType_t xAreInterruptSemaphoreTasksStillRunning( void )
{
    static uint32_t ulLastMasterLoopCounter = 0, ulLastCountingSemaphoreLoops = 0;

    /* If the demo tasks are running then it is expected that the loop counters
     * will have changed since this function was last called. */
    if( ulLastMasterLoopCounter == ulMasterLoops )
    {
        xErrorDetected = pdTRUE;
    }

    ulLastMasterLoopCounter = ulMasterLoops;

    if( ulLastCountingSemaphoreLoops == ulCountingSemaphoreLoops )
    {
        xErrorDetected = pdTRUE;
    }

    ulLastCountingSemaphoreLoops = ulCountingSemaphoreLoops++;

    /* Errors detected in the task itself will have latched xErrorDetected
     * to true. */

    return ( BaseType_t ) !xErrorDetected;
}
