Source to osfmk/mach/i386/flipc_dep.h

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/*
 * Copyright (c) 2000 Apple Computer, Inc. All rights reserved.
 *
 * @APPLE_LICENSE_HEADER_START@
 * 
 * The contents of this file constitute Original Code as defined in and
 * are subject to the Apple Public Source License Version 1.1 (the
 * "License").  You may not use this file except in compliance with the
 * License.  Please obtain a copy of the License at
 * http://www.apple.com/publicsource and read it before using this file.
 * 
 * This Original Code and all software distributed under the License are
 * distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY KIND, EITHER
 * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
 * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE OR NON-INFRINGEMENT.  Please see the
 * License for the specific language governing rights and limitations
 * under the License.
 * 
 * @APPLE_LICENSE_HEADER_END@
 */
/*
 * @OSF_COPYRIGHT@
 *
 */
/*
 * HISTORY
 * 
 * Revision 1.1.1.1  1998/09/22 21:05:31  wsanchez
 * Import of Mac OS X kernel (~semeria)
 *
 * Revision 1.1.1.1  1998/03/07 02:25:47  wsanchez
 * Import of OSF Mach kernel (~mburg)
 *
 * Revision 1.1.5.1  1995/06/13  18:20:42  sjs
 * 	Merge from flipc_shared.
 * 	[95/06/07            sjs]
 *
 * Revision 1.1.3.3  1995/02/21  17:23:16  randys
 * 	Re-indented code to four space indentation
 * 	[1995/02/21  16:26:50  randys]
 * 
 * Revision 1.1.3.2  1994/12/20  19:02:12  randys
 * 	Moved definition of flipc_simple_lock to flipc_cb.h
 * 	[1994/12/20  17:35:15  randys]
 * 
 * 	Moved the machine independent macros into mach/flipc_locks.h
 * 	[1994/12/20  16:44:14  randys]
 * 
 * 	Added filename in comment at top of file
 * 	[1994/12/19  20:29:36  randys]
 * 
 * 	Fixed incorrect return of lock_try
 * 	[1994/12/13  00:36:46  randys]
 * 
 * Revision 1.1.3.1  1994/12/12  17:46:29  randys
 * 	Putting initial flipc implementation under flipc_shared
 * 	[1994/12/12  16:27:51  randys]
 * 
 * Revision 1.1.1.2  1994/12/11  23:08:36  randys
 * 	Initial flipc code checkin.
 * 
 * $EndLog$
 */

/*
 * mach/i386/flipc_dep.h
 *
 * This file will have all of the FLIPC implementation machine dependent
 * defines that need to be visible to both kernel and AIL (eg. bus locks
 * and bus synchronization primitives).
 */

#ifndef _MACH_FLIPC_DEP_H_
#define _MACH_FLIPC_DEP_H_

/* For the 386, we don't need to wrap synchronization variable writes
   at all.  */
#define SYNCVAR_WRITE(statement)  statement

/* And similarly (I believe; check on this), for the 386 there isn't any
   requirement for write fences.  */
#define WRITE_FENCE()

/*
 * Flipc simple lock defines.  These are almost completely for the use
 * of the AIL; the reason they are in this file is that they need to
 * be initialized properly in the communications buffer initialization
 * routine.  Sigh.  Note in particular that the kernel has no defined
 * "simple_lock_yield_function", so it had better never expand the
 * macro simple_lock_acquire.
 *
 * These locks may be declared by "flipc_simple_lock lock;".  If they
 * are instead declared by FLIPC_DECL_SIMPLE_LOCK(class,lockname) they
 * may be used without initialization.
 */

#define SIMPLE_LOCK_INITIALIZER 0
#define FLIPC_DECL_SIMPLE_LOCK(class,lockname) \
class flipc_simple_lock (lockname) = SIMPLE_LOCK_INITIALIZER

/*
 * Lower case because they may be macros or functions.
 * I'll include the function prototypes just for examples here.
 */

#define flipc_simple_lock_init(lock)		\
do {						\
    *(lock) = SIMPLE_LOCK_INITIALIZER;		\
} while (0)

/*
 * Defines of the actual routines, for gcc.
 */

#define flipc_simple_lock_locked(lock) ((*lock) != SIMPLE_LOCK_INITIALIZER)

#ifdef __GNUC__
     extern __inline__ int flipc_simple_lock_try(flipc_simple_lock *lock)
{
    int r;
    __asm__ volatile("movl $1, %0; xchgl %0, %1" : "=&r" (r), "=m" (*lock));
    return !r;
}

/* I don't know why this requires an ASM, but I'll follow the leader. */
extern __inline__ void flipc_simple_lock_release(flipc_simple_lock *lock)
{
    register int t;				
    
    __asm__ volatile("xorl %0, %0; xchgl %0, %1" : "=&r" (t), "=m" (*lock));
} 
#else	/* __GNUC__ */
/* If we aren't compiling with gcc, the above need to be functions.  */
#endif	/* __GNUC__ */

#endif /* _MACH_FLIPC_DEP_H_ */