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/*-
* Copyright (c) 2010 Varnish Software AS
* All rights reserved.
*
* Author: Poul-Henning Kamp <phk@phk.freebsd.dk>
*
* 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 AND CONTRIBUTORS ``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 AUTHOR OR CONTRIBUTORS 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.
*
* Memory barriers
*
* XXX: It is utterly braindamaged, that no standard facility for this
* XXX: is available. The "just use pthreads locking" excuse does not
* XXX: make sense, and does not apply to two unthreaded programs sharing
* XXX: a memory segment.
*/

#ifndef VMB_H_INCLUDED
#define VMB_H_INCLUDED

#if defined(__FreeBSD__)
#include <sys/param.h>
#endif

#if defined(__FreeBSD__) && __FreeBSD_version >= 800058

#include <sys/types.h>
#include <machine/atomic.h>
#define VMB() mb()
#define VWMB() wmb()
#define VRMB() rmb()

#elif defined(__amd64__) && defined(__GNUC__)

#define VMB() __asm __volatile("mfence;" : : : "memory")
#define VWMB() __asm __volatile("sfence;" : : : "memory")
#define VRMB() __asm __volatile("lfence;" : : : "memory")

#elif defined(__arm__)

#define VMB()
#define VWMB()
#define VRMB()

#elif defined(__i386__) && defined(__GNUC__)

#define VMB() __asm __volatile("lock; addl $0,(%%esp)" : : : "memory")
#define VWMB() __asm __volatile("lock; addl $0,(%%esp)" : : : "memory")
#define VRMB() __asm __volatile("lock; addl $0,(%%esp)" : : : "memory")

#elif defined(__sparc64__) && defined(__GNUC__)

#define VMB() __asm__ __volatile__ ("membar #MemIssue": : :"memory")
#define VWMB() VMB()
#define VRMB() VMB()

#else

#define VMB_NEEDS_PTHREAD_WORKAROUND_THIS_IS_BAD_FOR_PERFORMANCE 1

void vmb_pthread(void);

#define VMB() vmb_pthread()
#define VWMB() vmb_pthread()
#define VRMB() vmb_pthread()

#endif

#endif /* VMB_H_INCLUDED */
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