initial commit, 4.5 stable

thirdparty/sdl/thread/pthread/SDL_syssem.c

@@ -0,0 +1,160 @@
+/*
+  Simple DirectMedia Layer
+  Copyright (C) 1997-2025 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>
+
+// Wrapper around POSIX 1003.1b semaphores
+
+#if defined(SDL_PLATFORM_MACOS) || defined(SDL_PLATFORM_IOS)
+// macOS 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_Semaphore *SDL_CreateSemaphore(Uint32 initial_value)
+{
+    SDL_Semaphore *sem = (SDL_Semaphore *)SDL_malloc(sizeof(SDL_Semaphore));
+    if (sem) {
+        if (sem_init(&sem->sem, 0, initial_value) < 0) {
+            SDL_SetError("sem_init() failed");
+            SDL_free(sem);
+            sem = NULL;
+        }
+    }
+    return sem;
+}
+
+void SDL_DestroySemaphore(SDL_Semaphore *sem)
+{
+    if (sem) {
+        sem_destroy(&sem->sem);
+        SDL_free(sem);
+    }
+}
+
+bool SDL_WaitSemaphoreTimeoutNS(SDL_Semaphore *sem, Sint64 timeoutNS)
+{
+#ifdef HAVE_SEM_TIMEDWAIT
+#ifndef HAVE_CLOCK_GETTIME
+    struct timeval now;
+#endif
+    struct timespec ts_timeout;
+#else
+    Uint64 stop_time;
+#endif
+
+    if (!sem) {
+        return true;
+    }
+
+    // Try the easy cases first
+    if (timeoutNS == 0) {
+        return (sem_trywait(&sem->sem) == 0);
+    }
+
+    if (timeoutNS < 0) {
+        int rc;
+        do {
+            rc = sem_wait(&sem->sem);
+        } while (rc < 0 && errno == EINTR);
+
+        return (rc == 0);
+    }
+
+#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_sec += (timeoutNS / SDL_NS_PER_SECOND);
+    ts_timeout.tv_nsec += (timeoutNS % SDL_NS_PER_SECOND);
+#else
+    gettimeofday(&now, NULL);
+
+    // Add our timeout to current time
+    ts_timeout.tv_sec = now.tv_sec + (timeoutNS / SDL_NS_PER_SECOND);
+    ts_timeout.tv_nsec = SDL_US_TO_NS(now.tv_usec) + (timeoutNS % SDL_NS_PER_SECOND);
+#endif
+
+    // Wrap the second if needed
+    while (ts_timeout.tv_nsec >= 1000000000) {
+        ts_timeout.tv_sec += 1;
+        ts_timeout.tv_nsec -= 1000000000;
+    }
+
+    // Wait.
+    int rc;
+    do {
+        rc = sem_timedwait(&sem->sem, &ts_timeout);
+    } while (rc < 0 && errno == EINTR);
+
+    return (rc == 0);
+#else
+    stop_time = SDL_GetTicksNS() + timeoutNS;
+    while (sem_trywait(&sem->sem) != 0) {
+        if (SDL_GetTicksNS() >= stop_time) {
+            return false;
+        }
+        SDL_DelayNS(100);
+    }
+    return true;
+#endif // HAVE_SEM_TIMEDWAIT
+}
+
+Uint32 SDL_GetSemaphoreValue(SDL_Semaphore *sem)
+{
+    int ret = 0;
+
+    if (!sem) {
+        return 0;
+    }
+
+    sem_getvalue(&sem->sem, &ret);
+    if (ret < 0) {
+        ret = 0;
+    }
+    return (Uint32)ret;
+}
+
+void SDL_SignalSemaphore(SDL_Semaphore *sem)
+{
+    if (!sem) {
+        return;
+    }
+
+    sem_post(&sem->sem);
+}
+
+#endif // SDL_PLATFORM_MACOS