/*
 * FreeRTOS V202212.00
 * Copyright (C) 2020 Amazon.com, Inc. or its affiliates. All Rights Reserved.
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy of
 * this software and associated documentation files (the "Software"), to deal in
 * the Software without restriction, including without limitation the rights to
 * use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of
 * the Software, and to permit persons to whom the Software is furnished to do so,
 * subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in all
 * copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
 * FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
 * COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER
 * IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
 * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 *
 * https://www.FreeRTOS.org
 * https://github.com/FreeRTOS
 *
 */

/**
 * The first test creates three tasks - two counter tasks (one continuous count
 * and one limited count) and one controller.  A "count" variable is shared
 * between all three tasks.  The two counter tasks should never be in a "ready"
 * state at the same time.  The controller task runs at the same priority as
 * the continuous count task, and at a lower priority than the limited count
 * task.
 *
 * One counter task loops indefinitely, incrementing the shared count variable
 * on each iteration.  To ensure it has exclusive access to the variable it
 * raises it's priority above that of the controller task before each
 * increment, lowering it again to it's original priority before starting the
 * next iteration.
 *
 * The other counter task increments the shared count variable on each
 * iteration of it's loop until the count has reached a limit of 0xff - at
 * which point it suspends itself.  It will not start a new loop until the
 * controller task has made it "ready" again by calling vTaskResume ().
 * This second counter task operates at a higher priority than controller
 * task so does not need to worry about mutual exclusion of the counter
 * variable.
 *
 * The controller task is in two sections.  The first section controls and
 * monitors the continuous count task.  When this section is operational the
 * limited count task is suspended.  Likewise, the second section controls
 * and monitors the limited count task.  When this section is operational the
 * continuous count task is suspended.
 *
 * In the first section the controller task first takes a copy of the shared
 * count variable.  To ensure mutual exclusion on the count variable it
 * suspends the continuous count task, resuming it again when the copy has been
 * taken.  The controller task then sleeps for a fixed period - during which
 * the continuous count task will execute and increment the shared variable.
 * When the controller task wakes it checks that the continuous count task
 * has executed by comparing the copy of the shared variable with its current
 * value.  This time, to ensure mutual exclusion, the scheduler itself is
 * suspended with a call to vTaskSuspendAll ().  This is for demonstration
 * purposes only and is not a recommended technique due to its inefficiency.
 *
 * After a fixed number of iterations the controller task suspends the
 * continuous count task, and moves on to its second section.
 *
 * At the start of the second section the shared variable is cleared to zero.
 * The limited count task is then woken from it's suspension by a call to
 * vTaskResume ().  As this counter task operates at a higher priority than
 * the controller task the controller task should not run again until the
 * shared variable has been counted up to the limited value causing the counter
 * task to suspend itself.  The next line after vTaskResume () is therefore
 * a check on the shared variable to ensure everything is as expected.
 *
 *
 * The second test consists of a couple of very simple tasks that post onto a
 * queue while the scheduler is suspended.  This test was added to test parts
 * of the scheduler not exercised by the first test.
 *
 *
 * The final set of two tasks implements a third test.  This simply raises the
 * priority of a task while the scheduler is suspended.  Again this test was
 * added to exercise parts of the code not covered by the first test.
 *
 * \page Priorities dynamic.c
 * \ingroup DemoFiles
 * <HR>
 */

/*
 * Changes from V2.0.0
 *
 + Delay periods are now specified using variables and constants of
 +    TickType_t rather than unsigned long.
 + Added a second, simple test that uses the functions
 +    vQueueReceiveWhenSuspendedTask() and vQueueSendWhenSuspendedTask().
 +
 + Changes from V3.1.1
 +
 + Added a third simple test that uses the vTaskPrioritySet() function
 +    while the scheduler is suspended.
 + Modified the controller task slightly to test the calling of
 +    vTaskResumeAll() while the scheduler is suspended.
 */

#include <stdlib.h>

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

/* Demo app include files. */
#include "dynamic.h"
#include "print.h"

/* Function that implements the "limited count" task as described above. */
static void vLimitedIncrementTask( void * pvParameters );

/* Function that implements the "continuous count" task as described above. */
static void vContinuousIncrementTask( void * pvParameters );

/* Function that implements the controller task as described above. */
static void vCounterControlTask( void * pvParameters );

/* The simple test functions that check sending and receiving while the
 * scheduler is suspended. */
static void vQueueReceiveWhenSuspendedTask( void * pvParameters );
static void vQueueSendWhenSuspendedTask( void * pvParameters );

/* The simple test functions that check raising and lowering of task priorities
 * while the scheduler is suspended. */
static void prvChangePriorityWhenSuspendedTask( void * pvParameters );
static void prvChangePriorityHelperTask( void * pvParameters );


/* Demo task specific constants. */
#define priSTACK_SIZE                ( ( unsigned short ) configMINIMAL_STACK_SIZE )
#define priSLEEP_TIME                ( ( TickType_t ) 50 )
#define priLOOPS                     ( 5 )
#define priMAX_COUNT                 ( ( unsigned long ) 0xff )
#define priNO_BLOCK                  ( ( TickType_t ) 0 )
#define priSUSPENDED_QUEUE_LENGTH    ( 1 )

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

/* Handles to the two counter tasks.  These could be passed in as parameters
 * to the controller task to prevent them having to be file scope. */
static TaskHandle_t xContinuousIncrementHandle, xLimitedIncrementHandle, xChangePriorityWhenSuspendedHandle;

/* The shared counter variable.  This is passed in as a parameter to the two
 * counter variables for demonstration purposes. */
static unsigned long ulCounter;

/* Variable used in a similar way by the test that checks the raising and
 * lowering of task priorities while the scheduler is suspended. */
static unsigned long ulPrioritySetCounter;

/* Variables used to check that the tasks are still operating without error.
 * Each complete iteration of the controller task increments this variable
 * provided no errors have been found.  The variable maintaining the same value
 * is therefore indication of an error. */
static unsigned short usCheckVariable = ( unsigned short ) 0;
static portBASE_TYPE xSuspendedQueueSendError = pdFALSE;
static portBASE_TYPE xSuspendedQueueReceiveError = pdFALSE;
static portBASE_TYPE xPriorityRaiseWhenSuspendedError = pdFALSE;

/* Queue used by the second test. */
QueueHandle_t xSuspendedTestQueue;

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

/*
 * Start the seven tasks as described at the top of the file.
 * Note that the limited count task is given a higher priority.
 */
void vStartDynamicPriorityTasks( void )
{
    xSuspendedTestQueue = xQueueCreate( priSUSPENDED_QUEUE_LENGTH, sizeof( unsigned long ) );
    xTaskCreate( vContinuousIncrementTask, "CONT_INC", priSTACK_SIZE, ( void * ) &ulCounter, tskIDLE_PRIORITY, &xContinuousIncrementHandle );
    xTaskCreate( vLimitedIncrementTask, "LIM_INC", priSTACK_SIZE, ( void * ) &ulCounter, tskIDLE_PRIORITY + 1, &xLimitedIncrementHandle );
    xTaskCreate( vCounterControlTask, "C_CTRL", priSTACK_SIZE, NULL, tskIDLE_PRIORITY, NULL );
    xTaskCreate( vQueueSendWhenSuspendedTask, "SUSP_SEND", priSTACK_SIZE, NULL, tskIDLE_PRIORITY, NULL );
    xTaskCreate( vQueueReceiveWhenSuspendedTask, "SUSP_RECV", priSTACK_SIZE, NULL, tskIDLE_PRIORITY, NULL );
    xTaskCreate( prvChangePriorityWhenSuspendedTask, "1st_P_CHANGE", priSTACK_SIZE, NULL, tskIDLE_PRIORITY + 1, NULL );
    xTaskCreate( prvChangePriorityHelperTask, "2nd_P_CHANGE", priSTACK_SIZE, NULL, tskIDLE_PRIORITY, &xChangePriorityWhenSuspendedHandle );
}
/*-----------------------------------------------------------*/

/*
 * Just loops around incrementing the shared variable until the limit has been
 * reached.  Once the limit has been reached it suspends itself.
 */
static void vLimitedIncrementTask( void * pvParameters )
{
    unsigned long * pulCounter;

    /* Take a pointer to the shared variable from the parameters passed into
     * the task. */
    pulCounter = ( unsigned long * ) pvParameters;

    /* This will run before the control task, so the first thing it does is
     * suspend - the control task will resume it when ready. */
    vTaskSuspend( NULL );

    for( ; ; )
    {
        /* Just count up to a value then suspend. */
        ( *pulCounter )++;

        if( *pulCounter >= priMAX_COUNT )
        {
            vTaskSuspend( NULL );
        }
    }
}
/*-----------------------------------------------------------*/

/*
 * Just keep counting the shared variable up.  The control task will suspend
 * this task when it wants.
 */
static void vContinuousIncrementTask( void * pvParameters )
{
    unsigned long * pulCounter;
    unsigned portBASE_TYPE uxOurPriority;

    /* Take a pointer to the shared variable from the parameters passed into
     * the task. */
    pulCounter = ( unsigned long * ) pvParameters;

    /* Query our priority so we can raise it when exclusive access to the
     * shared variable is required. */
    uxOurPriority = uxTaskPriorityGet( NULL );

    for( ; ; )
    {
        /* Raise our priority above the controller task to ensure a context
         * switch does not occur while we are accessing this variable. */
        vTaskPrioritySet( NULL, uxOurPriority + 1 );
        ( *pulCounter )++;
        vTaskPrioritySet( NULL, uxOurPriority );

        #if configUSE_PREEMPTION == 0
            taskYIELD();
        #endif
    }
}
/*-----------------------------------------------------------*/

/*
 * Controller task as described above.
 */
static void vCounterControlTask( void * pvParameters )
{
    unsigned long ulLastCounter;
    short sLoops;
    short sError = pdFALSE;
    const char * const pcTaskStartMsg = "Priority manipulation tasks started.\r\n";
    const char * const pcTaskFailMsg = "Priority manipulation Task Failed\r\n";

    /* Just to stop warning messages. */
    ( void ) pvParameters;

    /* Queue a message for printing to say the task has started. */
    vPrintDisplayMessage( &pcTaskStartMsg );

    for( ; ; )
    {
        /* Start with the counter at zero. */
        ulCounter = ( unsigned long ) 0;

        /* First section : */

        /* Check the continuous count task is running. */
        for( sLoops = 0; sLoops < priLOOPS; sLoops++ )
        {
            /* Suspend the continuous count task so we can take a mirror of the
             * shared variable without risk of corruption. */
            vTaskSuspend( xContinuousIncrementHandle );
            ulLastCounter = ulCounter;
            vTaskResume( xContinuousIncrementHandle );

            /* Now delay to ensure the other task has processor time. */
            vTaskDelay( priSLEEP_TIME );

            /* Check the shared variable again.  This time to ensure mutual
             * exclusion the whole scheduler will be locked.  This is just for
             * demo purposes! */
            vTaskSuspendAll();
            {
                if( ulLastCounter == ulCounter )
                {
                    /* The shared variable has not changed.  There is a problem
                     * with the continuous count task so flag an error. */
                    sError = pdTRUE;
                    xTaskResumeAll();
                    vPrintDisplayMessage( &pcTaskFailMsg );
                    vTaskSuspendAll();
                }
            }
            xTaskResumeAll();
        }

        /* Second section: */

        /* Suspend the continuous counter task so it stops accessing the shared variable. */
        vTaskSuspend( xContinuousIncrementHandle );

        /* Reset the variable. */
        ulCounter = ( unsigned long ) 0;

        /* Resume the limited count task which has a higher priority than us.
         * We should therefore not return from this call until the limited count
         * task has suspended itself with a known value in the counter variable.
         * The scheduler suspension is not necessary but is included for test
         * purposes. */
        vTaskSuspendAll();
        vTaskResume( xLimitedIncrementHandle );
        xTaskResumeAll();

        /* Does the counter variable have the expected value? */
        if( ulCounter != priMAX_COUNT )
        {
            sError = pdTRUE;
            vPrintDisplayMessage( &pcTaskFailMsg );
        }

        if( sError == pdFALSE )
        {
            /* If no errors have occurred then increment the check variable. */
            portENTER_CRITICAL();
            usCheckVariable++;
            portEXIT_CRITICAL();
        }

        #if configUSE_PREEMPTION == 0
            taskYIELD();
        #endif

        /* Resume the continuous count task and do it all again. */
        vTaskResume( xContinuousIncrementHandle );
    }
}
/*-----------------------------------------------------------*/

static void vQueueSendWhenSuspendedTask( void * pvParameters )
{
    static unsigned long ulValueToSend = ( unsigned long ) 0;
    const char * const pcTaskStartMsg = "Queue send while suspended task started.\r\n";
    const char * const pcTaskFailMsg = "Queue send while suspended failed.\r\n";

    /* Just to stop warning messages. */
    ( void ) pvParameters;

    /* Queue a message for printing to say the task has started. */
    vPrintDisplayMessage( &pcTaskStartMsg );

    for( ; ; )
    {
        vTaskSuspendAll();
        {
            /* We must not block while the scheduler is suspended! */
            if( xQueueSend( xSuspendedTestQueue, ( void * ) &ulValueToSend, priNO_BLOCK ) != pdTRUE )
            {
                if( xSuspendedQueueSendError == pdFALSE )
                {
                    xTaskResumeAll();
                    vPrintDisplayMessage( &pcTaskFailMsg );
                    vTaskSuspendAll();
                }

                xSuspendedQueueSendError = pdTRUE;
            }
        }
        xTaskResumeAll();

        vTaskDelay( priSLEEP_TIME );

        ++ulValueToSend;
    }
}
/*-----------------------------------------------------------*/

static void vQueueReceiveWhenSuspendedTask( void * pvParameters )
{
    static unsigned long ulExpectedValue = ( unsigned long ) 0, ulReceivedValue;
    const char * const pcTaskStartMsg = "Queue receive while suspended task started.\r\n";
    const char * const pcTaskFailMsg = "Queue receive while suspended failed.\r\n";
    portBASE_TYPE xGotValue;

    /* Just to stop warning messages. */
    ( void ) pvParameters;

    /* Queue a message for printing to say the task has started. */
    vPrintDisplayMessage( &pcTaskStartMsg );

    for( ; ; )
    {
        do
        {
            /* Suspending the scheduler here is fairly pointless and
             * undesirable for a normal application.  It is done here purely
             * to test the scheduler.  The inner xTaskResumeAll() should
             * never return pdTRUE as the scheduler is still locked by the
             * outer call. */
            vTaskSuspendAll();
            {
                vTaskSuspendAll();
                {
                    xGotValue = xQueueReceive( xSuspendedTestQueue, ( void * ) &ulReceivedValue, priNO_BLOCK );
                }

                if( xTaskResumeAll() )
                {
                    xSuspendedQueueReceiveError = pdTRUE;
                }
            }
            xTaskResumeAll();

            #if configUSE_PREEMPTION == 0
                taskYIELD();
            #endif
        } while( xGotValue == pdFALSE );

        if( ulReceivedValue != ulExpectedValue )
        {
            if( xSuspendedQueueReceiveError == pdFALSE )
            {
                vPrintDisplayMessage( &pcTaskFailMsg );
            }

            xSuspendedQueueReceiveError = pdTRUE;
        }

        ++ulExpectedValue;
    }
}
/*-----------------------------------------------------------*/

static void prvChangePriorityWhenSuspendedTask( void * pvParameters )
{
    const char * const pcTaskStartMsg = "Priority change when suspended task started.\r\n";
    const char * const pcTaskFailMsg = "Priority change when suspended task failed.\r\n";

    /* Just to stop warning messages. */
    ( void ) pvParameters;

    /* Queue a message for printing to say the task has started. */
    vPrintDisplayMessage( &pcTaskStartMsg );

    for( ; ; )
    {
        /* Start with the counter at 0 so we know what the counter should be
         * when we check it next. */
        ulPrioritySetCounter = ( unsigned long ) 0;

        /* Resume the helper task.  At this time it has a priority lower than
         * ours so no context switch should occur. */
        vTaskResume( xChangePriorityWhenSuspendedHandle );

        /* Check to ensure the task just resumed has not executed. */
        portENTER_CRITICAL();
        {
            if( ulPrioritySetCounter != ( unsigned long ) 0 )
            {
                xPriorityRaiseWhenSuspendedError = pdTRUE;
                vPrintDisplayMessage( &pcTaskFailMsg );
            }
        }
        portEXIT_CRITICAL();

        /* Now try raising the priority while the scheduler is suspended. */
        vTaskSuspendAll();
        {
            vTaskPrioritySet( xChangePriorityWhenSuspendedHandle, ( configMAX_PRIORITIES - 1 ) );

            /* Again, even though the helper task has a priority greater than
             * ours, it should not have executed yet because the scheduler is
             * suspended. */
            portENTER_CRITICAL();
            {
                if( ulPrioritySetCounter != ( unsigned long ) 0 )
                {
                    xPriorityRaiseWhenSuspendedError = pdTRUE;
                    vPrintDisplayMessage( &pcTaskFailMsg );
                }
            }
            portEXIT_CRITICAL();
        }
        xTaskResumeAll();

        /* Now the scheduler has been resumed the helper task should
         * immediately preempt us and execute.  When it executes it will increment
         * the ulPrioritySetCounter exactly once before suspending itself.
         *
         * We should now always find the counter set to 1. */
        portENTER_CRITICAL();
        {
            if( ulPrioritySetCounter != ( unsigned long ) 1 )
            {
                xPriorityRaiseWhenSuspendedError = pdTRUE;
                vPrintDisplayMessage( &pcTaskFailMsg );
            }
        }
        portEXIT_CRITICAL();

        /* Delay until we try this again. */
        vTaskDelay( priSLEEP_TIME * 2 );

        /* Set the priority of the helper task back ready for the next
         * execution of this task. */
        vTaskSuspendAll();
        vTaskPrioritySet( xChangePriorityWhenSuspendedHandle, tskIDLE_PRIORITY );
        xTaskResumeAll();
    }
}
/*-----------------------------------------------------------*/

static void prvChangePriorityHelperTask( void * pvParameters )
{
    /* Just to stop warning messages. */
    ( void ) pvParameters;

    for( ; ; )
    {
        /* This is the helper task for prvChangePriorityWhenSuspendedTask().
         * It has it's priority raised and lowered.  When it runs it simply
         * increments the counter then suspends itself again.  This allows
         * prvChangePriorityWhenSuspendedTask() to know how many times it has
         * executed. */
        ulPrioritySetCounter++;
        vTaskSuspend( NULL );
    }
}
/*-----------------------------------------------------------*/

/* Called to check that all the created tasks are still running without error. */
portBASE_TYPE xAreDynamicPriorityTasksStillRunning( void )
{
/* Keep a history of the check variables so we know if it has been incremented
 * since the last call. */
    static unsigned short usLastTaskCheck = ( unsigned short ) 0;
    portBASE_TYPE xReturn = pdTRUE;

    /* Check the tasks are still running by ensuring the check variable
     * is still incrementing. */

    if( usCheckVariable == usLastTaskCheck )
    {
        /* The check has not incremented so an error exists. */
        xReturn = pdFALSE;
    }

    if( xSuspendedQueueSendError == pdTRUE )
    {
        xReturn = pdFALSE;
    }

    if( xSuspendedQueueReceiveError == pdTRUE )
    {
        xReturn = pdFALSE;
    }

    if( xPriorityRaiseWhenSuspendedError == pdTRUE )
    {
        xReturn = pdFALSE;
    }

    usLastTaskCheck = usCheckVariable;
    return xReturn;
}