futex.h

/*
 * Copyright 2009  Raphael Kubo da Costa <kubito@gmail.com>
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

#ifndef __FUTEX_H
#define __FUTEX_H

/**
 * Wrapper around SYS_futex with FUTEX_WAIT.
 *
 * @param addr The address of the futex.
 * @param val1 The value to compare the futex to.
 *
 * @retval 0           Woken by a @p FUTEX_WAKE call.
 * @retval ETIMEDOUT   The wait has timed out.
 * @retval EWOULDBLOCK @p addr is not equal to @p val1.
 * @retval EINTR       A signal has interrupted the wait.
 */
int futex_wait(void *addr, int val1);

/**
 * Wrapper around SYS_futex with FUTEX_WAKE.
 *
 * @param addr The address of the futex.
 * @param n    The number of threads to awake (or INT_MAX to wake all)
 *
 * @return The number of threads which were awakened.
 */
int futex_wake(void *addr, int n);

#endif /* __FUTEX_H */