FreeBSD/Linux Kernel Cross Reference
sys/sqt/mutex.h

     /* 
      * Mach Operating System
      * Copyright (c) 1991 Carnegie Mellon University
      * Copyright (c) 1991 Sequent Computer Systems
      * All Rights Reserved.
      * 
      * Permission to use, copy, modify and distribute this software and its
      * documentation is hereby granted, provided that both the copyright
      * notice and this permission notice appear in all copies of the
     * software, derivative works or modified versions, and any portions
     * thereof, and that both notices appear in supporting documentation.
     * 
     * CARNEGIE MELLON AND SEQUENT COMPUTER SYSTEMS ALLOW FREE USE OF
     * THIS SOFTWARE IN ITS "AS IS" CONDITION.  CARNEGIE MELLON AND
     * SEQUENT COMPUTER SYSTEMS DISCLAIM ANY LIABILITY OF ANY KIND FOR
     * ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
     * 
     * Carnegie Mellon requests users of this software to return to
     * 
     *  Software Distribution Coordinator  or  Software.Distribution@CS.CMU.EDU
     *  School of Computer Science
     *  Carnegie Mellon University
     *  Pittsburgh PA 15213-3890
     * 
     * any improvements or extensions that they make and grant Carnegie Mellon 
     * the rights to redistribute these changes.
     */
    
    /*
     * HISTORY
     * $Log:        mutex.h,v $
     * Revision 2.3  91/07/31  18:03:14  dbg
     *      Changed copyright.
     *      [91/07/31            dbg]
     * 
     * Revision 2.2  91/05/08  12:58:12  dbg
     *      Adapted for pure kernel.  Removed gate code, since Symmetry
     *      doesn't use it.  Re-implemented Dynix semaphores.
     *      [90/09/24            dbg]
     * 
     */
    
    /*
     * $Header: mutex.h,v 2.3 91/07/31 18:03:14 dbg Exp $
     *
     * mutex.h
     *      Implementation dependent mutual-exclusion interface definitions.
     *
     * i386 version.
     */
    
    /*
     * Revision 1.1  89/07/05  13:15:39  kak
     * Initial revision
     * 
     * Revision 2.25  89/02/27  10:38:58  djg
     * increased slic sychrinisation timing to 22Mhz (=12 cycles)
     * 
     * Revision 2.24  89/02/20  08:02:20  djg
     * corrected comments on SLICSYNC timeing and added a missing
     * #if MHz=20 ... nop
     * 
     * Revision 2.23  88/11/10  08:25:17  djg
     * bak242 
     * 
     */
    
    #ifndef _SQT_MUTEX_H_
    #define _SQT_MUTEX_H_
    
    /*
     * i386 does not use gates.  Leave typedef here for compilation.
     */
    typedef unsigned char   gate_t;         /* gate number */
    
    /*
     * Use Mach simple_lock_data_t instead of Dynix lock_t.
     */
    #include <kern/lock.h>
    
    /*
     * Semaphores.
     * Very simple mono-processor implementation.  See sqt/sema.c.
     *
     * These semaphores assume non-signalable sleep priorities, initial value
     * == 0 or 1.  Implements "random" queueing.
     *
     * This is sufficient for (eg) zd driver, sm, misc others.  Anything
     * more fancy need to be done in driver itself.
     */
    
    struct sema {
            char            lock;
            char            waiting;
            short           count;
    };
    typedef struct sema     sema_t;
    
    /*
    * Processor interrupt masking (lowest level mutex).
    */
   
   #if     !defined(GENASSYM) && !defined(lint)
   
   #define DISABLE() \
           asm volatile("cli")
   
   #define ENABLE() \
           asm volatile("sti")
   
   #endif  !defined(GENASSYM) && !defined(lint)
   
   /*
    * Locks.
    *
    * init_lock() interface provided as a macro to avoid need to represent
    * SLIC gates numbers.
    */
   
   #define L_UNLOCKED      0
   #define L_LOCKED        1
   
   #define CPLOCKFAIL      -1              /* illegal SPL value */
   
   #define init_lock(l,g)  simple_lock_init(l)
   
   #define v_lock(l,p)     (simple_unlock(l), splx(p))
   
   #endif  _SQT_MUTEX_H_

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