SDL_syssem.c
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/*
Simple DirectMedia Layer
Copyright (C) 1997-2016 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"
#ifndef _GNU_SOURCE
#define _GNU_SOURCE
#endif
#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");
}
retval = sem_wait(&sem->sem);
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: */
Uint32
uint32_t Uint32
An unsigned 32-bit integer type.
Definition: SDL_stdinc.h:155
end
GLuint GLuint end
Definition: SDL_opengl.h:1564
SDL_SemPost
int SDL_SemPost(SDL_sem *sem)
Definition: SDL_syssem.c:200
SDL_MUTEX_TIMEDOUT
#define SDL_MUTEX_TIMEDOUT
Definition: SDL_mutex.h:44
SDL_thread.h
retval
SDL_bool retval
Definition: testgamecontroller.c:65
SDL_MUTEX_MAXWAIT
#define SDL_MUTEX_MAXWAIT
Definition: SDL_mutex.h:49
SDL_GetTicks
Uint32 SDL_GetTicks(void)
Get the number of milliseconds since the SDL library initialization.
SDL_SemWaitTimeout
int SDL_SemWaitTimeout(SDL_sem *sem, Uint32 timeout)
Definition: SDL_syssem.c:150
SDL_SemTryWait
int SDL_SemTryWait(SDL_sem *sem)
Definition: SDL_syssem.c:130
SDL_SemWait
int SDL_SemWait(SDL_sem *sem)
Definition: SDL_syssem.c:180
SDL_free
void SDL_free(void *mem)
SDL_semaphore
Definition: SDL_syssem.c:76
SDL_Delay
#define SDL_Delay
Definition: SDL_dynapi_overrides.h:490
NULL
#define NULL
Definition: begin_code.h:143
SDL_OutOfMemory
#define SDL_OutOfMemory()
Definition: SDL_error.h:52
SDL_SetError
#define SDL_SetError
Definition: SDL_dynapi_overrides.h:36
SDL_SemValue
Uint32 SDL_SemValue(SDL_sem *sem)
Definition: SDL_syssem.c:186
timeout
GLbitfield GLuint64 timeout
Definition: SDL_opengl_glext.h:1483
SDL_semaphore::sem
sem_t sem
Definition: SDL_syssem.c:44
SDL_malloc
#define SDL_malloc
Definition: SDL_dynapi_overrides.h:380
SDL_timer.h
SDL_TICKS_PASSED
#define SDL_TICKS_PASSED(A, B)
Compare SDL ticks values, and return true if A has passed B.
Definition: SDL_timer.h:56
SDL_DestroySemaphore
void SDL_DestroySemaphore(SDL_sem *sem)
Definition: SDL_syssem.c:111
SDL_CreateSemaphore
SDL_sem * SDL_CreateSemaphore(Uint32 initial_value)
Definition: SDL_syssem.c:85