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/*
* RTLinux semaphore implementation
*
* Written by Michael Barabanov <baraban@fsmlabs.com>
* Copyright (C) Finite State Machine Labs Inc., 2000
* Released under the terms of the GPL Version 2
*
*/
#include <rtl_sched.h>
#include <rtl_sema.h>
#include <rtl_sync.h>
#include <errno.h>
int sem_init(sem_t *sem, int pshared, unsigned int value)
{
rtl_wait_init (&sem->wait);
sem->value = value;
rtl_spin_lock_init(&sem->lock);
return 0;
}
int sem_destroy(sem_t *sem)
{
return 0;
}
int sem_getvalue(sem_t *sem, int *sval)
{
return sem->value;
}
int __sem_trywait(sem_t *sem)
{
if (sem->value > 0) {
--(sem->value);
return 0;
} else {
errno = EAGAIN;
return -1;
}
}
int sem_trywait(sem_t *sem)
{
rtl_irqstate_t flags;
int ret;
rtl_spin_lock_irqsave (&sem->lock, flags);
ret = __sem_trywait(sem);
rtl_spin_unlock_irqrestore(&sem->lock, flags);
return ret;
}
int sem_wait(sem_t *sem)
{
int ret;
rtl_irqstate_t flags;
rtl_spin_lock_irqsave (&sem->lock, flags);
while (__sem_trywait(sem)) {
if (errno != EAGAIN) {
rtl_spin_unlock_irqrestore(&sem->lock, flags);
return -1;
}
ret = rtl_wait_sleep (&sem->wait, &sem->lock);
pthread_testcancel();
rtl_spin_lock(&sem->lock);
}
rtl_spin_unlock_irqrestore(&sem->lock, flags);
return 0;
}
#ifdef _RTL_POSIX_TIMEOUTS
int sem_timedwait(sem_t *sem, const struct timespec *abstime)
{
rtl_sigset_t ret;
rtl_irqstate_t flags;
hrtime_t save_resume_time;
pthread_t self = pthread_self();
hrtime_t timeout;
if (abstime == (const struct timespec *) &self->timeval) {
timeout = self->timeval;
} else {
timeout = timespec_to_ns(abstime);
}
timeout = __rtl_fix_timeout_for_clock(CLOCK_REALTIME, timeout);
rtl_spin_lock_irqsave (&sem->lock, flags);
while (__sem_trywait(sem)) {
if (errno != EAGAIN) {
rtl_spin_unlock_irqrestore(&sem->lock, flags);
return -1;
}
save_resume_time = self->resume_time;
__rtl_setup_timeout(self, timeout);
ret = rtl_wait_sleep (&sem->wait, &sem->lock);
pthread_testcancel();
rtl_spin_lock(&sem->lock);
self->resume_time = save_resume_time;
if (RTL_TIMED_OUT(&ret)) {
errno = ETIMEDOUT;
rtl_spin_unlock_irqrestore(&sem->lock, flags);
return -1;
}
if (RTL_SIGINTR(&ret)) {
errno = EINTR;
rtl_spin_unlock_irqrestore(&sem->lock, flags);
return -1;
}
}
rtl_spin_unlock_irqrestore(&sem->lock, flags);
return 0;
}
#endif
int sem_post(sem_t *sem)
{
rtl_irqstate_t flags;
rtl_spin_lock_irqsave (&sem->lock, flags);
++(sem->value);
rtl_wait_wakeup (&sem->wait);
rtl_spin_unlock_irqrestore(&sem->lock, flags);
rtl_schedule(); /* make it fast! */
return 0;
}
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