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

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• Hash : 24c86b55
  Author :
  Date : 2014-09-11T19:24:42
  

  [X11] Reconcile logical keyboard state with physical state on FocusIn since the window system doesn't do it for us like other platforms. This prevents sticky keys and missed keys when going in and out of focus, for example Alt would appear to stick if switching away from an SDL app with Alt-Tab and had to be pressed again. CR: Sam

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• src/thread/generic/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"
  
  /* An implementation of semaphores using mutexes and condition variables */
  
  #include "SDL_timer.h"
  #include "SDL_thread.h"
  #include "SDL_systhread_c.h"
  
  
  #if SDL_THREADS_DISABLED
  
  SDL_sem *
  SDL_CreateSemaphore(Uint32 initial_value)
  {
      SDL_SetError("SDL not built with thread support");
      return (SDL_sem *) 0;
  }
  
  void
  SDL_DestroySemaphore(SDL_sem * sem)
  {
  }
  
  int
  SDL_SemTryWait(SDL_sem * sem)
  {
      return SDL_SetError("SDL not built with thread support");
  }
  
  int
  SDL_SemWaitTimeout(SDL_sem * sem, Uint32 timeout)
  {
      return SDL_SetError("SDL not built with thread support");
  }
  
  int
  SDL_SemWait(SDL_sem * sem)
  {
      return SDL_SetError("SDL not built with thread support");
  }
  
  Uint32
  SDL_SemValue(SDL_sem * sem)
  {
      return 0;
  }
  
  int
  SDL_SemPost(SDL_sem * sem)
  {
      return SDL_SetError("SDL not built with thread support");
  }
  
  #else
  
  struct SDL_semaphore
  {
      Uint32 count;
      Uint32 waiters_count;
      SDL_mutex *count_lock;
      SDL_cond *count_nonzero;
  };
  
  SDL_sem *
  SDL_CreateSemaphore(Uint32 initial_value)
  {
      SDL_sem *sem;
  
      sem = (SDL_sem *) SDL_malloc(sizeof(*sem));
      if (!sem) {
          SDL_OutOfMemory();
          return NULL;
      }
      sem->count = initial_value;
      sem->waiters_count = 0;
  
      sem->count_lock = SDL_CreateMutex();
      sem->count_nonzero = SDL_CreateCond();
      if (!sem->count_lock || !sem->count_nonzero) {
          SDL_DestroySemaphore(sem);
          return NULL;
      }
  
      return sem;
  }
  
  /* WARNING:
     You cannot call this function when another thread is using the semaphore.
  */
  void
  SDL_DestroySemaphore(SDL_sem * sem)
  {
      if (sem) {
          sem->count = 0xFFFFFFFF;
          while (sem->waiters_count > 0) {
              SDL_CondSignal(sem->count_nonzero);
              SDL_Delay(10);
          }
          SDL_DestroyCond(sem->count_nonzero);
          if (sem->count_lock) {
              SDL_LockMutex(sem->count_lock);
              SDL_UnlockMutex(sem->count_lock);
              SDL_DestroyMutex(sem->count_lock);
          }
          SDL_free(sem);
      }
  }
  
  int
  SDL_SemTryWait(SDL_sem * sem)
  {
      int retval;
  
      if (!sem) {
          return SDL_SetError("Passed a NULL semaphore");
      }
  
      retval = SDL_MUTEX_TIMEDOUT;
      SDL_LockMutex(sem->count_lock);
      if (sem->count > 0) {
          --sem->count;
          retval = 0;
      }
      SDL_UnlockMutex(sem->count_lock);
  
      return retval;
  }
  
  int
  SDL_SemWaitTimeout(SDL_sem * sem, Uint32 timeout)
  {
      int retval;
  
      if (!sem) {
          return SDL_SetError("Passed a NULL semaphore");
      }
  
      /* A timeout of 0 is an easy case */
      if (timeout == 0) {
          return SDL_SemTryWait(sem);
      }
  
      SDL_LockMutex(sem->count_lock);
      ++sem->waiters_count;
      retval = 0;
      while ((sem->count == 0) && (retval != SDL_MUTEX_TIMEDOUT)) {
          retval = SDL_CondWaitTimeout(sem->count_nonzero,
                                       sem->count_lock, timeout);
      }
      --sem->waiters_count;
      if (retval == 0) {
          --sem->count;
      }
      SDL_UnlockMutex(sem->count_lock);
  
      return retval;
  }
  
  int
  SDL_SemWait(SDL_sem * sem)
  {
      return SDL_SemWaitTimeout(sem, SDL_MUTEX_MAXWAIT);
  }
  
  Uint32
  SDL_SemValue(SDL_sem * sem)
  {
      Uint32 value;
  
      value = 0;
      if (sem) {
          SDL_LockMutex(sem->count_lock);
          value = sem->count;
          SDL_UnlockMutex(sem->count_lock);
      }
      return value;
  }
  
  int
  SDL_SemPost(SDL_sem * sem)
  {
      if (!sem) {
          return SDL_SetError("Passed a NULL semaphore");
      }
  
      SDL_LockMutex(sem->count_lock);
      if (sem->waiters_count > 0) {
          SDL_CondSignal(sem->count_nonzero);
      }
      ++sem->count;
      SDL_UnlockMutex(sem->count_lock);
  
      return 0;
  }
  
  #endif /* SDL_THREADS_DISABLED */
  /* vi: set ts=4 sw=4 expandtab: */
  

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