src/thread/pthread/SDL_syssem.c
changeset 1361 19418e4422cb
child 1402 d910939febfa
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/thread/pthread/SDL_syssem.c	Thu Feb 16 10:11:48 2006 +0000
@@ -0,0 +1,174 @@
+/*
+    SDL - Simple DirectMedia Layer
+    Copyright (C) 1997-2006 Sam Lantinga
+
+    This library is free software; you can redistribute it and/or
+    modify it under the terms of the GNU Lesser General Public
+    License as published by the Free Software Foundation; either
+    version 2.1 of the License, or (at your option) any later version.
+
+    This library is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+    Lesser General Public License for more details.
+
+    You should have received a copy of the GNU Lesser General Public
+    License along with this library; if not, write to the Free Software
+    Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
+
+    Sam Lantinga
+    slouken@libsdl.org
+*/
+
+#include <pthread.h>
+#include <semaphore.h>
+
+#include "SDL_thread.h"
+#include "SDL_timer.h"
+
+/* Wrapper around POSIX 1003.1b semaphores */
+
+#if MACOSX
+#define USE_NAMED_SEMAPHORES 1
+#endif /* MACOSX */
+
+struct SDL_semaphore {
+	sem_t *sem;
+#if !USE_NAMED_SEMAPHORES
+	sem_t sem_data;
+#endif
+};
+
+/* 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 USE_NAMED_SEMAPHORES
+		static int semnum = 0;
+		char name[32];
+
+		SDL_snprintf(name, SDL_arraysize(name), "/SDL_sem-%d-%4.4d", getpid(), semnum++);
+		sem->sem = sem_open(name, O_CREAT, 0600, initial_value);
+		if ( sem->sem == (sem_t *)SEM_FAILED ) {
+			SDL_SetError("sem_open(%s) failed", name);
+			SDL_free(sem);
+			sem = NULL;
+		} else {
+			sem_unlink(name);
+		}
+#else
+		if ( sem_init(&sem->sem_data, 0, initial_value) < 0 ) {
+			SDL_SetError("sem_init() failed");
+			SDL_free(sem);
+			sem = NULL;
+		} else {
+			sem->sem = &sem->sem_data;
+		}
+#endif /* USE_NAMED_SEMAPHORES */
+	} else {
+		SDL_OutOfMemory();
+	}
+	return sem;
+}
+
+void SDL_DestroySemaphore(SDL_sem *sem)
+{
+	if ( sem ) {
+#if USE_NAMED_SEMAPHORES
+		sem_close(sem->sem);
+#else
+		sem_destroy(sem->sem);
+#endif
+		SDL_free(sem);
+	}
+}
+
+int SDL_SemTryWait(SDL_sem *sem)
+{
+	int retval;
+
+	if ( ! sem ) {
+		SDL_SetError("Passed a NULL semaphore");
+		return -1;
+	}
+	retval = SDL_MUTEX_TIMEDOUT;
+	if ( sem_trywait(sem->sem) == 0 ) {
+		retval = 0;
+	}
+	return retval;
+}
+
+int SDL_SemWait(SDL_sem *sem)
+{
+	int retval;
+
+	if ( ! sem ) {
+		SDL_SetError("Passed a NULL semaphore");
+		return -1;
+	}
+
+	retval = sem_wait(sem->sem);
+	if ( retval < 0 ) {
+		SDL_SetError("sem_wait() failed");
+	}
+	return retval;
+}
+
+int SDL_SemWaitTimeout(SDL_sem *sem, Uint32 timeout)
+{
+	int retval;
+
+	if ( ! sem ) {
+		SDL_SetError("Passed a NULL semaphore");
+		return -1;
+	}
+
+	/* Try the easy cases first */
+	if ( timeout == 0 ) {
+		return SDL_SemTryWait(sem);
+	}
+	if ( timeout == SDL_MUTEX_MAXWAIT ) {
+		return SDL_SemWait(sem);
+	}
+
+	/* Ack!  We have to busy wait... */
+	timeout += SDL_GetTicks();
+	do {
+		retval = SDL_SemTryWait(sem);
+		if ( retval == 0 ) {
+			break;
+		}
+		SDL_Delay(1);
+	} while ( SDL_GetTicks() < timeout );
+
+	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 ) {
+		SDL_SetError("Passed a NULL semaphore");
+		return -1;
+	}
+
+	retval = sem_post(sem->sem);
+	if ( retval < 0 ) {
+		SDL_SetError("sem_post() failed");
+	}
+	return retval;
+}