text: /*
    Simple DirectMedia Layer
    Copyright (C) 1997-2014 Sam Lantinga <slouken@libsdl.org>
  
    This software is provided 'as-is', without any express or implied
    warranty.  In no event will the authors be held liable for any damages
    arising from the use of this software.
  
    Permission is granted to anyone to use this software for any purpose,
    including commercial applications, and to alter it and redistribute it
    freely, subject to the following restrictions:
  
    1. The origin of this software must not be misrepresented; you must not
       claim that you wrote the original software. If you use this software
       in a product, an acknowledgment in the product documentation would be
       appreciated but is not required.
    2. Altered source versions must be plainly marked as such, and must not be
       misrepresented as being the original software.
    3. This notice may not be removed or altered from any source distribution.
  */
  #include "../../SDL_internal.h"
  
  #include <errno.h>
  #include <pthread.h>
  #include <semaphore.h>
  #include <sys/time.h>
  
  #include "SDL_thread.h"
  #include "SDL_timer.h"
  
  /* Wrapper around POSIX 1003.1b semaphores */
  
  #if defined(__MACOSX__) || defined(__IPHONEOS__)
  /* Mac OS X doesn't support sem_getvalue() as of version 10.4 */
  #include "../generic/SDL_syssem.c"
  #else
  
  struct SDL_semaphore
  {
      sem_t sem;
  };
  
  /* Create a semaphore, initialized with value */
  SDL_sem *
  SDL_CreateSemaphore(Uint32 initial_value)
  {
      SDL_sem *sem = (SDL_sem *) SDL_malloc(sizeof(SDL_sem));
      if (sem) {
          if (sem_init(&sem->sem, 0, initial_value) < 0) {
              SDL_SetError("sem_init() failed");
              SDL_free(sem);
              sem = NULL;
          }
      } else {
          SDL_OutOfMemory();
      }
      return sem;
  }
  
  void
  SDL_DestroySemaphore(SDL_sem * sem)
  {
      if (sem) {
          sem_destroy(&sem->sem);
          SDL_free(sem);
      }
  }
  
  int
  SDL_SemTryWait(SDL_sem * sem)
  {
      int retval;
  
      if (!sem) {
          return SDL_SetError("Passed a NULL semaphore");
      }
      retval = SDL_MUTEX_TIMEDOUT;
      if (sem_trywait(&sem->sem) == 0) {
          retval = 0;
      }
      return retval;
  }
  
  int
  SDL_SemWait(SDL_sem * sem)
  {
      int retval;
  
      if (!sem) {
          return SDL_SetError("Passed a NULL semaphore");
      }
  
      retval = sem_wait(&sem->sem);
      if (retval < 0) {
          retval = SDL_SetError("sem_wait() failed");
      }
      return retval;
  }
  
  int
  SDL_SemWaitTimeout(SDL_sem * sem, Uint32 timeout)
  {
      int retval;
  #ifdef HAVE_SEM_TIMEDWAIT
      struct timeval now;
      struct timespec ts_timeout;
  #else
      Uint32 end;
  #endif
  
      if (!sem) {
          return SDL_SetError("Passed a NULL semaphore");
      }
  
      /* Try the easy cases first */
      if (timeout == 0) {
          return SDL_SemTryWait(sem);
      }
      if (timeout == SDL_MUTEX_MAXWAIT) {
          return SDL_SemWait(sem);
      }
  
  #ifdef HAVE_SEM_TIMEDWAIT
      /* Setup the timeout. sem_timedwait doesn't wait for
      * a lapse of time, but until we reach a certain time.
      * This time is now plus the timeout.
      */
      gettimeofday(&now, NULL);
  
      /* Add our timeout to current time */
      now.tv_usec += (timeout % 1000) * 1000;
      now.tv_sec += timeout / 1000;
  
      /* Wrap the second if needed */
      if ( now.tv_usec >= 1000000 ) {
          now.tv_usec -= 1000000;
          now.tv_sec ++;
      }
  
      /* Convert to timespec */
      ts_timeout.tv_sec = now.tv_sec;
      ts_timeout.tv_nsec = now.tv_usec * 1000;
  
      /* Wait. */
      do {
          retval = sem_timedwait(&sem->sem, &ts_timeout);
      } while (retval < 0 && errno == EINTR);
  
      if (retval < 0) {
          if (errno == ETIMEDOUT) {
              retval = SDL_MUTEX_TIMEDOUT;
          } else {
              SDL_SetError(strerror(errno));
          }
      }
  #else
      end = SDL_GetTicks() + timeout;
      while ((retval = SDL_SemTryWait(sem)) == SDL_MUTEX_TIMEDOUT) {
          if (SDL_TICKS_PASSED(SDL_GetTicks(), end)) {
              break;
          }
          SDL_Delay(1);
      }
  #endif /* HAVE_SEM_TIMEDWAIT */
  
      return retval;
  }
  
  Uint32
  SDL_SemValue(SDL_sem * sem)
  {
      int ret = 0;
      if (sem) {
          sem_getvalue(&sem->sem, &ret);
          if (ret < 0) {
              ret = 0;
          }
      }
      return (Uint32) ret;
  }
  
  int
  SDL_SemPost(SDL_sem * sem)
  {
      int retval;
  
      if (!sem) {
          return SDL_SetError("Passed a NULL semaphore");
      }
  
      retval = sem_post(&sem->sem);
      if (retval < 0) {
          SDL_SetError("sem_post() failed");
      }
      return retval;
  }
  
  #endif /* __MACOSX__ */
  /* vi: set ts=4 sw=4 expandtab: */
  