kc3-lang/SDL/src/thread/psp/SDL_sysmutex.c

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• Hash : 3dcb451f
  Author :
  Date : 2014-04-09T21:29:19
  

  Added a README file regarding WinRT support To note, this file is currently formatted with CRLF line endings, rather than LF, to allow the file to be viewed with Notepad.

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• src/thread/psp/SDL_sysmutex.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 mutexes using semaphores */
  
  #include "SDL_thread.h"
  #include "SDL_systhread_c.h"
  
  
  struct SDL_mutex
  {
      int recursive;
      SDL_threadID owner;
      SDL_sem *sem;
  };
  
  /* Create a mutex */
  SDL_mutex *
  SDL_CreateMutex(void)
  {
      SDL_mutex *mutex;
  
      /* Allocate mutex memory */
      mutex = (SDL_mutex *) SDL_malloc(sizeof(*mutex));
      if (mutex) {
          /* Create the mutex semaphore, with initial value 1 */
          mutex->sem = SDL_CreateSemaphore(1);
          mutex->recursive = 0;
          mutex->owner = 0;
          if (!mutex->sem) {
              SDL_free(mutex);
              mutex = NULL;
          }
      } else {
          SDL_OutOfMemory();
      }
      return mutex;
  }
  
  /* Free the mutex */
  void
  SDL_DestroyMutex(SDL_mutex * mutex)
  {
      if (mutex) {
          if (mutex->sem) {
              SDL_DestroySemaphore(mutex->sem);
          }
          SDL_free(mutex);
      }
  }
  
  /* Lock the semaphore */
  int
  SDL_mutexP(SDL_mutex * mutex)
  {
  #if SDL_THREADS_DISABLED
      return 0;
  #else
      SDL_threadID this_thread;
  
      if (mutex == NULL) {
          return SDL_SetError("Passed a NULL mutex");
      }
  
      this_thread = SDL_ThreadID();
      if (mutex->owner == this_thread) {
          ++mutex->recursive;
      } else {
          /* The order of operations is important.
             We set the locking thread id after we obtain the lock
             so unlocks from other threads will fail.
           */
          SDL_SemWait(mutex->sem);
          mutex->owner = this_thread;
          mutex->recursive = 0;
      }
  
      return 0;
  #endif /* SDL_THREADS_DISABLED */
  }
  
  /* Unlock the mutex */
  int
  SDL_mutexV(SDL_mutex * mutex)
  {
  #if SDL_THREADS_DISABLED
      return 0;
  #else
      if (mutex == NULL) {
          return SDL_SetError("Passed a NULL mutex");
      }
  
      /* If we don't own the mutex, we can't unlock it */
      if (SDL_ThreadID() != mutex->owner) {
          return SDL_SetError("mutex not owned by this thread");
      }
  
      if (mutex->recursive) {
          --mutex->recursive;
      } else {
          /* The order of operations is important.
             First reset the owner so another thread doesn't lock
             the mutex and set the ownership before we reset it,
             then release the lock semaphore.
           */
          mutex->owner = 0;
          SDL_SemPost(mutex->sem);
      }
      return 0;
  #endif /* SDL_THREADS_DISABLED */
  }
  
  /* vi: set ts=4 sw=4 expandtab: */
  

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