1*1fb62fb0SOlivier Houchard /*
2*1fb62fb0SOlivier Houchard * Copyright 2011-2015 Samy Al Bahra.
3*1fb62fb0SOlivier Houchard * Copyright 2011 David Joseph.
4*1fb62fb0SOlivier Houchard * All rights reserved.
5*1fb62fb0SOlivier Houchard *
6*1fb62fb0SOlivier Houchard * Redistribution and use in source and binary forms, with or without
7*1fb62fb0SOlivier Houchard * modification, are permitted provided that the following conditions
8*1fb62fb0SOlivier Houchard * are met:
9*1fb62fb0SOlivier Houchard * 1. Redistributions of source code must retain the above copyright
10*1fb62fb0SOlivier Houchard * notice, this list of conditions and the following disclaimer.
11*1fb62fb0SOlivier Houchard * 2. Redistributions in binary form must reproduce the above copyright
12*1fb62fb0SOlivier Houchard * notice, this list of conditions and the following disclaimer in the
13*1fb62fb0SOlivier Houchard * documentation and/or other materials provided with the distribution.
14*1fb62fb0SOlivier Houchard *
15*1fb62fb0SOlivier Houchard * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
16*1fb62fb0SOlivier Houchard * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
17*1fb62fb0SOlivier Houchard * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
18*1fb62fb0SOlivier Houchard * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
19*1fb62fb0SOlivier Houchard * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
20*1fb62fb0SOlivier Houchard * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
21*1fb62fb0SOlivier Houchard * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
22*1fb62fb0SOlivier Houchard * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
23*1fb62fb0SOlivier Houchard * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
24*1fb62fb0SOlivier Houchard * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
25*1fb62fb0SOlivier Houchard * SUCH DAMAGE.
26*1fb62fb0SOlivier Houchard */
27*1fb62fb0SOlivier Houchard
28*1fb62fb0SOlivier Houchard #include <ck_barrier.h>
29*1fb62fb0SOlivier Houchard #include <ck_pr.h>
30*1fb62fb0SOlivier Houchard
31*1fb62fb0SOlivier Houchard void
ck_barrier_centralized(struct ck_barrier_centralized * barrier,struct ck_barrier_centralized_state * state,unsigned int n_threads)32*1fb62fb0SOlivier Houchard ck_barrier_centralized(struct ck_barrier_centralized *barrier,
33*1fb62fb0SOlivier Houchard struct ck_barrier_centralized_state *state,
34*1fb62fb0SOlivier Houchard unsigned int n_threads)
35*1fb62fb0SOlivier Houchard {
36*1fb62fb0SOlivier Houchard unsigned int sense, value;
37*1fb62fb0SOlivier Houchard
38*1fb62fb0SOlivier Houchard /*
39*1fb62fb0SOlivier Houchard * Every execution context has a sense associated with it.
40*1fb62fb0SOlivier Houchard * This sense is reversed when the barrier is entered. Every
41*1fb62fb0SOlivier Houchard * thread will spin on the global sense until the last thread
42*1fb62fb0SOlivier Houchard * reverses it.
43*1fb62fb0SOlivier Houchard */
44*1fb62fb0SOlivier Houchard sense = state->sense = ~state->sense;
45*1fb62fb0SOlivier Houchard value = ck_pr_faa_uint(&barrier->value, 1);
46*1fb62fb0SOlivier Houchard if (value == n_threads - 1) {
47*1fb62fb0SOlivier Houchard ck_pr_store_uint(&barrier->value, 0);
48*1fb62fb0SOlivier Houchard ck_pr_fence_memory();
49*1fb62fb0SOlivier Houchard ck_pr_store_uint(&barrier->sense, sense);
50*1fb62fb0SOlivier Houchard return;
51*1fb62fb0SOlivier Houchard }
52*1fb62fb0SOlivier Houchard
53*1fb62fb0SOlivier Houchard ck_pr_fence_atomic_load();
54*1fb62fb0SOlivier Houchard while (sense != ck_pr_load_uint(&barrier->sense))
55*1fb62fb0SOlivier Houchard ck_pr_stall();
56*1fb62fb0SOlivier Houchard
57*1fb62fb0SOlivier Houchard ck_pr_fence_acquire();
58*1fb62fb0SOlivier Houchard return;
59*1fb62fb0SOlivier Houchard }
60