lock.h

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    1 /* 
    2  * Mach Operating System
    3  * Copyright (c) 1991,1990 Carnegie Mellon University
    4  * All Rights Reserved.
    5  * 
    6  * Permission to use, copy, modify and distribute this software and its
    7  * documentation is hereby granted, provided that both the copyright
    8  * notice and this permission notice appear in all copies of the
    9  * software, derivative works or modified versions, and any portions
   10  * thereof, and that both notices appear in supporting documentation.
   11  * 
   12  * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS"
   13  * CONDITION.  CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND FOR
   14  * ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
   15  * 
   16  * Carnegie Mellon requests users of this software to return to
   17  * 
   18  *  Software Distribution Coordinator  or  Software.Distribution@CS.CMU.EDU
   19  *  School of Computer Science
   20  *  Carnegie Mellon University
   21  *  Pittsburgh PA 15213-3890
   22  * 
   23  * any improvements or extensions that they make and grant Carnegie Mellon
   24  * the rights to redistribute these changes.
   25  */
   26 
   27 /*
   28  * HISTORY
   29  * $Log:        lock.h,v $
   30  * Revision 2.4  91/11/12  11:50:47  rvb
   31  *      Added simple_lock_pause.
   32  *      [91/11/12            rpd]
   33  * 
   34  * Revision 2.3  91/05/14  16:11:00  mrt
   35  *      Correcting copyright
   36  * 
   37  * Revision 2.2  91/05/08  12:39:08  dbg
   38  *      Created.
   39  *      [91/03/21            dbg]
   40  * 
   41  */
   42 
   43 /*
   44  * Machine-dependent simple locks for the i386.
   45  */
   46 #ifndef _I386_LOCK_H_
   47 #define _I386_LOCK_H_
   48 
   49 /*
   50  *      All of the locking routines are built from calls on
   51  *      a locked-exchange operation.  Values of the lock are
   52  *      0 for unlocked, 1 for locked.
   53  */
   54 
   55 #ifdef  __GNUC__
   56 
   57 /*
   58  *      The code here depends on the GNU C compiler.
   59  */
   60 
   61 #define _simple_lock_xchg_(lock, new_val) \
   62     ({  register int _old_val_; \
   63         asm volatile("xchgl %0, %2" \
   64                     : "=r" (_old_val_) \
   65                     : "" (new_val), "m" (*(lock)) \
   66                     ); \
   67         _old_val_; \
   68     })
   69 
   70 #define simple_lock_init(l) \
   71         ((l)->lock_data = 0)
   72 
   73 #define simple_lock(l) \
   74     ({ \
   75         while(_simple_lock_xchg_(l, 1)) \
   76             while (*(volatile int *)&(l)->lock_data) \
   77                 continue; \
   78         0; \
   79     })
   80 
   81 #define simple_unlock(l) \
   82         (_simple_lock_xchg_(l, 0))
   83 
   84 #define simple_lock_try(l) \
   85         (!_simple_lock_xchg_(l, 1))
   86 
   87 /*
   88  *      General bit-lock routines.
   89  */
   90 #define bit_lock(bit, l) \
   91     ({ \
   92         asm volatile("  jmp     1f      \n\
   93                     0:  btl     %0, %1  \n\
   94                         jb      0b      \n\
   95                     1:  lock            \n\
   96                         btsl    %0, %1  \n\
   97                         jb      0b" \
   98                     : \
   99                     : "r" (bit), "m" (*(volatile int *)(l))); \
  100         0; \
  101     })
  102 
  103 #define bit_unlock(bit, l) \
  104     ({ \
  105         asm volatile("  lock            \n\
  106                         btrl    %0, %1" \
  107                     : \
  108                     : "r" (bit), "m" (*(volatile int *)(l))); \
  109         0; \
  110     })
  111 
  112 /*
  113  *      Set or clear individual bits in a long word.
  114  *      The locked access is needed only to lock access
  115  *      to the word, not to individual bits.
  116  */
  117 #define i_bit_set(bit, l) \
  118     ({ \
  119         asm volatile("  lock            \n\
  120                         btsl    %0, %1" \
  121                     : \
  122                     : "r" (bit), "m" (*(l)) ); \
  123         0; \
  124     })
  125 
  126 #define i_bit_clear(bit, l) \
  127     ({ \
  128         asm volatile("  lock            \n\
  129                         btrl    %0, %1" \
  130                     : \
  131                     : "r" (bit), "m" (*(l)) ); \
  132         0; \
  133     })
  134 
  135 #endif  /* __GNUC__ */
  136 
  137 extern void simple_lock_pause();
  138 
  139 #endif  /* _I386_LOCK_H_ */

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FreeBSD/Linux Kernel Cross Reference sys/i386/lock.h

FreeBSD/Linux Kernel Cross Reference
sys/i386/lock.h