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/* Spin locks (native Windows implementation).
Copyright (C) 2019-2021 Free Software Foundation, Inc.
This file is free software: you can redistribute it and/or modify
it under the terms of the GNU Lesser General Public License as
published by the Free Software Foundation; either version 2.1 of the
License, or (at your option) any later version.
This file is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public License
along with this program. If not, see <https://www.gnu.org/licenses/>. */
/* Written by Bruno Haible <bruno@clisp.org>, 2019. */
#include <config.h>
/* Specification. */
#include "windows-spin.h"
#include <errno.h>
void
glwthread_spin_init (glwthread_spinlock_t *lock)
{
lock->word = 0;
MemoryBarrier ();
}
int
glwthread_spin_lock (glwthread_spinlock_t *lock)
{
/* Wait until lock->word becomes 0, then replace it with 1. */
/* InterlockedCompareExchange
<https://docs.microsoft.com/en-us/windows/win32/api/winnt/nf-winnt-interlockedcompareexchange> */
while (InterlockedCompareExchange (&lock->word, 1, 0))
;
return 0;
}
int
glwthread_spin_trylock (glwthread_spinlock_t *lock)
{
/* If lock->word is 0, then replace it with 1. */
/* InterlockedCompareExchange
<https://docs.microsoft.com/en-us/windows/win32/api/winnt/nf-winnt-interlockedcompareexchange> */
if (InterlockedCompareExchange (&lock->word, 1, 0))
return EBUSY;
return 0;
}
int
glwthread_spin_unlock (glwthread_spinlock_t *lock)
{
/* If lock->word is 1, then replace it with 0. */
/* InterlockedCompareExchange
<https://docs.microsoft.com/en-us/windows/win32/api/winnt/nf-winnt-interlockedcompareexchange> */
if (!InterlockedCompareExchange (&lock->word, 0, 1))
return EINVAL;
return 0;
}
int
glwthread_spin_destroy (glwthread_spinlock_t *lock)
{
return 0;
}
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