FreeRTOS-Plus/Source/Reliance-Edge/os/freertos/services/osmutex.c

/*             ----> DO NOT REMOVE THE FOLLOWING NOTICE <----

                   Copyright (c) 2014-2015 Datalight, Inc.
                       All Rights Reserved Worldwide.

    This program is free software; you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation; use version 2 of the License.

    This program is distributed in the hope that it will be useful,
    but "AS-IS," 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 along
    with this program; if not, write to the Free Software Foundation, Inc.,
    51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
*/
/*  Businesses and individuals that for commercial or other reasons cannot
    comply with the terms of the GPLv2 license may obtain a commercial license
    before incorporating Reliance Edge into proprietary software for
    distribution in any form.  Visit http://www.datalight.com/reliance-edge for
    more information.
*/
/** @file
    @brief Implements a synchronization object to provide mutual exclusion.
*/
#include <FreeRTOS.h>
#include <semphr.h>

#include <redfs.h>
#include <redosdeviations.h>

#if REDCONF_TASK_COUNT > 1U


static SemaphoreHandle_t xMutex;
#if defined(configSUPPORT_STATIC_ALLOCATION) && (configSUPPORT_STATIC_ALLOCATION == 1)
static StaticSemaphore_t xMutexBuffer;
#endif


/** @brief Initialize the mutex.

    After initialization, the mutex is in the released state.

    The behavior of calling this function when the mutex is still initialized
    is undefined.

    @return A negated ::REDSTATUS code indicating the operation result.

    @retval 0   Operation was successful.
*/
REDSTATUS RedOsMutexInit(void)
{
    REDSTATUS ret = 0;
    
  #if defined(configSUPPORT_STATIC_ALLOCATION) && (configSUPPORT_STATIC_ALLOCATION == 1)
    xMutex = xSemaphoreCreateMutexStatic(&xMutexBuffer);
    
    if(xMutex == NULL)
    {
        /*  The only error case for xSemaphoreCreateMutexStatic is that the mutex
            buffer parameter is NULL, which is not the case.
        */
        REDERROR();
        ret = -RED_EINVAL;
    }        
    
  #else
    xMutex = xSemaphoreCreateMutex();
    if(xMutex == NULL)
    {
        ret = -RED_ENOMEM;
    }
  #endif

    return ret;
}


/** @brief Uninitialize the mutex.

    The behavior of calling this function when the mutex is not initialized is
    undefined; likewise, the behavior of uninitializing the mutex when it is
    in the acquired state is undefined.

    @return A negated ::REDSTATUS code indicating the operation result.

    @retval 0   Operation was successful.
*/
REDSTATUS RedOsMutexUninit(void)
{
    vSemaphoreDelete(xMutex);
    xMutex = NULL;

    return 0;
}


/** @brief Acquire the mutex.

    The behavior of calling this function when the mutex is not initialized is
    undefined; likewise, the behavior of recursively acquiring the mutex is
    undefined.
*/
void RedOsMutexAcquire(void)
{
    while(xSemaphoreTake(xMutex, portMAX_DELAY) != pdTRUE)
    {
    }
}


/** @brief Release the mutex.

    The behavior is undefined in the following cases:

    - Releasing the mutex when the mutex is not initialized.
    - Releasing the mutex when it is not in the acquired state.
    - Releasing the mutex from a task or thread other than the one which
      acquired the mutex.
*/
void RedOsMutexRelease(void)
{
    BaseType_t xSuccess;

    xSuccess = xSemaphoreGive(xMutex);
    REDASSERT(xSuccess == pdTRUE);
    IGNORE_ERRORS(xSuccess);
}

#endif