text: /*
   * Amazon FreeRTOS+POSIX V1.0.3
   * Copyright (C) 2018 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.
   *
   * http://aws.amazon.com/freertos
   * http://www.FreeRTOS.org
   */
  
  /**
   * @file semaphore.h
   * @brief Semaphores.
   *
   * http://pubs.opengroup.org/onlinepubs/9699919799/basedefs/semaphore.h.html
   */
  
  #ifndef _FREERTOS_POSIX_SEMAPHORE_H_
  #define _FREERTOS_POSIX_SEMAPHORE_H_
  
  /* FreeRTOS+POSIX includes. */
  #include "FreeRTOS_POSIX/time.h"
  #include "FreeRTOS_POSIX_types.h"
  
  /**
   * @brief Semaphore type.
   */
  typedef PosixSemType_t sem_t;
  
  /**
   * @brief Destroy an unnamed semaphore.
   *
   * http://pubs.opengroup.org/onlinepubs/9699919799/functions/sem_destroy.html
   */
  int sem_destroy( sem_t * sem );
  
  /**
   * @brief Get the value of a semaphore.
   *
   * http://pubs.opengroup.org/onlinepubs/9699919799/functions/sem_getvalue.html
   */
  int sem_getvalue( sem_t * sem,
                    int * sval );
  
  /**
   * @brief Initialize an unnamed semaphore.
   *
   * http://pubs.opengroup.org/onlinepubs/9699919799/functions/sem_init.html
   *
   * @note pshared is ignored. Semaphores will always be considered "shared".
   */
  int sem_init( sem_t * sem,
                int pshared,
                unsigned value );
  
  /**
   * @brief Unlock a semaphore.
   *
   * http://pubs.opengroup.org/onlinepubs/9699919799/functions/sem_post.html
   */
  int sem_post( sem_t * sem );
  
  /**
   * @brief Lock a semaphore with timeout.
   *
   * http://pubs.opengroup.org/onlinepubs/9699919799/functions/sem_timedwait.html
   */
  int sem_timedwait( sem_t * sem,
                     const struct timespec * abstime );
  
  /**
   * @brief Lock a semaphore if available.
   *
   * http://pubs.opengroup.org/onlinepubs/9699919799/functions/sem_trywait.html
   */
  int sem_trywait( sem_t * sem );
  
  /**
   * @brief Lock a semaphore.
   *
   * http://pubs.opengroup.org/onlinepubs/9699919799/functions/sem_wait.html
   *
   * @note Deadlock detection is not implemented.
   */
  int sem_wait( sem_t * sem );
  
  #endif /* ifndef _FREERTOS_POSIX_SEMAPHORE_H_ */
  