kc3-lang/SDL/src/thread/windows/SDL_syssem.c

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• Hash : 9c398852
  Author :
  Date : 2014-11-22T22:20:40
  

  Corrected header file documentation comment.

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• src/thread/windows/SDL_syssem.c

• /*
    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"
  
  #if SDL_THREAD_WINDOWS
  
  /* Semaphore functions using the Win32 API */
  
  #include "../../core/windows/SDL_windows.h"
  
  #include "SDL_thread.h"
  
  struct SDL_semaphore
  {
      HANDLE id;
      LONG count;
  };
  
  
  /* Create a semaphore */
  SDL_sem *
  SDL_CreateSemaphore(Uint32 initial_value)
  {
      SDL_sem *sem;
  
      /* Allocate sem memory */
      sem = (SDL_sem *) SDL_malloc(sizeof(*sem));
      if (sem) {
          /* Create the semaphore, with max value 32K */
          sem->id = CreateSemaphore(NULL, initial_value, 32 * 1024, NULL);
          sem->count = initial_value;
          if (!sem->id) {
              SDL_SetError("Couldn't create semaphore");
              SDL_free(sem);
              sem = NULL;
          }
      } else {
          SDL_OutOfMemory();
      }
      return (sem);
  }
  
  /* Free the semaphore */
  void
  SDL_DestroySemaphore(SDL_sem * sem)
  {
      if (sem) {
          if (sem->id) {
              CloseHandle(sem->id);
              sem->id = 0;
          }
          SDL_free(sem);
      }
  }
  
  int
  SDL_SemWaitTimeout(SDL_sem * sem, Uint32 timeout)
  {
      int retval;
      DWORD dwMilliseconds;
  
      if (!sem) {
          return SDL_SetError("Passed a NULL sem");
      }
  
      if (timeout == SDL_MUTEX_MAXWAIT) {
          dwMilliseconds = INFINITE;
      } else {
          dwMilliseconds = (DWORD) timeout;
      }
      switch (WaitForSingleObject(sem->id, dwMilliseconds)) {
      case WAIT_OBJECT_0:
          InterlockedDecrement(&sem->count);
          retval = 0;
          break;
      case WAIT_TIMEOUT:
          retval = SDL_MUTEX_TIMEDOUT;
          break;
      default:
          retval = SDL_SetError("WaitForSingleObject() failed");
          break;
      }
      return retval;
  }
  
  int
  SDL_SemTryWait(SDL_sem * sem)
  {
      return SDL_SemWaitTimeout(sem, 0);
  }
  
  int
  SDL_SemWait(SDL_sem * sem)
  {
      return SDL_SemWaitTimeout(sem, SDL_MUTEX_MAXWAIT);
  }
  
  /* Returns the current count of the semaphore */
  Uint32
  SDL_SemValue(SDL_sem * sem)
  {
      if (!sem) {
          SDL_SetError("Passed a NULL sem");
          return 0;
      }
      return (Uint32)sem->count;
  }
  
  int
  SDL_SemPost(SDL_sem * sem)
  {
      if (!sem) {
          return SDL_SetError("Passed a NULL sem");
      }
      /* Increase the counter in the first place, because
       * after a successful release the semaphore may
       * immediately get destroyed by another thread which
       * is waiting for this semaphore.
       */
      InterlockedIncrement(&sem->count);
      if (ReleaseSemaphore(sem->id, 1, NULL) == FALSE) {
          InterlockedDecrement(&sem->count);      /* restore */
          return SDL_SetError("ReleaseSemaphore() failed");
      }
      return 0;
  }
  
  #endif /* SDL_THREAD_WINDOWS */
  
  /* vi: set ts=4 sw=4 expandtab: */
  

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