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Annotation of kernel/mach/i386/simple_lock.h, revision 1.1.1.1

1.1       root        1: /*
                      2:  * Copyright (c) 1999 Apple Computer, Inc. All rights reserved.
                      3:  *
                      4:  * @APPLE_LICENSE_HEADER_START@
                      5:  * 
                      6:  * Portions Copyright (c) 1999 Apple Computer, Inc.  All Rights
                      7:  * Reserved.  This file contains Original Code and/or Modifications of
                      8:  * Original Code as defined in and that are subject to the Apple Public
                      9:  * Source License Version 1.1 (the "License").  You may not use this file
                     10:  * except in compliance with the License.  Please obtain a copy of the
                     11:  * License at http://www.apple.com/publicsource and read it before using
                     12:  * this file.
                     13:  * 
                     14:  * The Original Code and all software distributed under the License are
                     15:  * distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY KIND, EITHER
                     16:  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
                     17:  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
                     18:  * FITNESS FOR A PARTICULAR PURPOSE OR NON-INFRINGEMENT.  Please see the
                     19:  * License for the specific language governing rights and limitations
                     20:  * under the License.
                     21:  * 
                     22:  * @APPLE_LICENSE_HEADER_END@
                     23:  */
                     24: 
                     25: /*
                     26:  * Copyright (c) 1992 NeXT Computer, Inc.
                     27:  *
                     28:  * Simple spin locks.
                     29:  *
                     30:  * HISTORY
                     31:  *
                     32:  * 19 November 1992 ? at NeXT
                     33:  *     Created.
                     34:  */
                     35:  
                     36: #import <mach/boolean.h>
                     37: 
                     38: #ifndef        _MACH_I386_SIMPLE_LOCK_H_
                     39: #define _MACH_I386_SIMPLE_LOCK_H_
                     40: 
                     41: #define _MACHINE_SIMPLE_LOCK_DATA_
                     42: 
                     43: struct slock {
                     44:     boolean_t          locked;
                     45: };
                     46: 
                     47: typedef struct slock           simple_lock_data_t;
                     48: typedef simple_lock_data_t     *simple_lock_t;
                     49: 
                     50: static __inline__
                     51: void
                     52: simple_lock_init(
                     53:     simple_lock_t      slock
                     54: )
                     55: {
                     56:     slock->locked = FALSE;
                     57: }
                     58: 
                     59: static __inline__
                     60: boolean_t
                     61: simple_lock_try(
                     62:     simple_lock_t      slock
                     63: )
                     64: {
                     65:     boolean_t          result;
                     66:     
                     67:     asm volatile(
                     68:        "xchgl %1,%0; xorl %3,%0"
                     69:            : "=r" (result), "=m" (slock->locked)
                     70:            : "0" (TRUE), "i" (TRUE));
                     71:            
                     72:     return (result);
                     73: }
                     74: 
                     75: static __inline__
                     76: void
                     77: simple_lock(
                     78:     simple_lock_t      slock
                     79: )
                     80: {    
                     81:     do
                     82:        {
                     83:            while (slock->locked)
                     84:                continue;
                     85:        }
                     86:     while (!simple_lock_try(slock));
                     87: }
                     88: 
                     89: static __inline__
                     90: void
                     91: simple_unlock(
                     92:     simple_lock_t      slock
                     93: )
                     94: {
                     95:     boolean_t          result;
                     96:     
                     97:     asm volatile(
                     98:        "xchgl %1,%0"
                     99:            : "=r" (result), "=m" (slock->locked)
                    100:            : "0" (FALSE));
                    101: }
                    102: 
                    103: #endif /* _MACH_I386_SIMPLE_LOCK_H_ */

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