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/*

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

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

    *                                                                         *

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

    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.

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    critical systems.

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    licensing and training services.

*/

/*

 * This file defines the button push task and ISR as described at the top of

 * main.c.  The ISR is called from a wrapper function defined in ButtonISR.s26.

 */

/* Kernel includes. */

#include "FreeRTOS.h"

#include "task.h"

#include "semphr.h"

/* The LED output used by the button push task. */

#define butLED1   P7_bit.no7

/* A short delay used for button debouncing. */

#define butDEBOUNCE_DELAY       ( 200 / portTICK_RATE_MS )

/* The semaphore used to synchronise the button push task with the interrupt. */

static xSemaphoreHandle xButtonSemaphore;

/*

 * The definition of the button task itself.  See the comments at the top of

 * main.c.

 */

void vButtonTask( void *pvParameters )

{

        /* Ensure the semaphore is created before it gets used. */

        vSemaphoreCreateBinary( xButtonSemaphore );

        for( ;; )

        {

                /* Block on the semaphore to wait for an interrupt event.  The semaphore

                is 'given' from vButtonISRHandler() below.  Using portMAX_DELAY as the

                block time will cause the task to block indefinitely provided

                INCLUDE_vTaskSuspend is set to 1 in FreeRTOSConfig.h. */

                xSemaphoreTake( xButtonSemaphore, portMAX_DELAY );

                /* The button must have been pushed for this line to be executed.

                Simply toggle the LED. */

                butLED1 = !butLED1;

                /* Wait a short time then clear any pending button pushes as a crude

                method of debouncing the switch.  xSemaphoreTake() uses a block time of

                zero this time so it returns immediately rather than waiting for the

                interrupt to occur. */

                vTaskDelay( butDEBOUNCE_DELAY );

                xSemaphoreTake( xButtonSemaphore, 0 );

        }

}

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

/*

 * The C portion of the interrupt handler.  Interrupts are triggered by pushing

 * the button on the target board.  This interrupt can cause a context switch

 * so has an assembly file wrapper defined within ButtonISR.s26.

 */

void vButtonISRHandler( void )

{

short sHigherPriorityTaskWoken = pdFALSE;

        /* 'Give' the semaphore to unblock the button task. */

        xSemaphoreGiveFromISR( xButtonSemaphore, &sHigherPriorityTaskWoken );

        /* If giving the semaphore unblocked a task, and the unblocked task has a

        priority that is higher than the currently running task, then

        sHigherPriorityTaskWoken will have been set to pdTRUE.  Passing a pdTRUE

        value to portYIELD_FROM_ISR() will cause this interrupt to return directly

        to the higher priority unblocked task. */

        portYIELD_FROM_ISR( sHigherPriorityTaskWoken );

}

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