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/* Copyright (c) 2013, Linaro Limited
* All rights reserved.
*
* SPDX-License-Identifier: BSD-3-Clause
*/
#include <odp_barrier.h>
#include <odp_sync.h>
#include <odp_spin_internal.h>
void odp_barrier_init(odp_barrier_t *barrier, int count)
{
barrier->count = count;
barrier->bar = 0;
odp_sync_stores();
}
/*
* Efficient barrier_sync -
*
* Barriers are initialized with a count of the number of callers
* that must sync on the barrier before any may proceed.
*
* To avoid race conditions and to permit the barrier to be fully
* reusable, the barrier value cycles between 0..2*count-1. When
* synchronizing the wasless variable simply tracks which half of
* the cycle the barrier was in upon entry. Exit is when the
* barrier crosses to the other half of the cycle.
*/
void odp_barrier_wait(odp_barrier_t *barrier)
{
uint32_t count;
int wasless;
odp_sync_stores();
wasless = barrier->bar < barrier->count;
count = odp_atomic_fetch_inc_u32(&barrier->bar);
if (count == 2*barrier->count-1) {
barrier->bar = 0;
} else {
while ((barrier->bar < barrier->count) == wasless)
odp_spin();
}
odp_mem_barrier();
}
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