/*
 * Copyright (c) 2013, 2021 Jonas 'Sortie' Termansen.
 *
 * Permission to use, copy, modify, and distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 *
 * pthread/pthread_cond_signal.c
 * Signals a condition.
 */

#include <sys/futex.h>

#include <stddef.h>
#include <pthread.h>

int pthread_cond_signal(pthread_cond_t* cond)
{
	pthread_mutex_lock(&cond->lock);
	if ( cond->first )
	{
		struct pthread_cond_elem* elem = cond->first;
		if ( elem->next )
			elem->next->prev = elem->prev;
		else
			cond->last = elem->prev;
		cond->first = elem->next;
		elem->next = NULL;
		elem->prev = NULL;
		__atomic_store_n(&elem->woken, 1, __ATOMIC_SEQ_CST);
		futex(&elem->woken, FUTEX_WAKE, 1, NULL);
	}
	pthread_mutex_unlock(&cond->lock);
	return 0;
}