sdl

SDL_syssem.c (4850B)

---

 /*
   Simple DirectMedia Layer
   Copyright (C) 1997-2020 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 <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");
     }
 
     do {
         retval = sem_wait(&sem->sem);
     } while (retval < 0 && errno == EINTR);
 
     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
 #ifndef HAVE_CLOCK_GETTIME
     struct timeval now;
 #endif
     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.
     */
 #ifdef HAVE_CLOCK_GETTIME
     clock_gettime(CLOCK_REALTIME, &ts_timeout);
 
     /* Add our timeout to current time */
     ts_timeout.tv_nsec += (timeout % 1000) * 1000000;
     ts_timeout.tv_sec += timeout / 1000;
 #else
     gettimeofday(&now, NULL);
 
     /* Add our timeout to current time */
     ts_timeout.tv_sec = now.tv_sec + (timeout / 1000);
     ts_timeout.tv_nsec = (now.tv_usec + (timeout % 1000) * 1000) * 1000;
 #endif
 
     /* Wrap the second if needed */
     if (ts_timeout.tv_nsec > 1000000000) {
         ts_timeout.tv_sec += 1;
         ts_timeout.tv_nsec -= 1000000000;
     }
 
     /* 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("sem_timedwait returned an error: %s", 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: */