1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
|
/*
* Mach Operating System
* Copyright (c) 1991,1990 Carnegie Mellon University
* 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 ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS"
* CONDITION. CARNEGIE MELLON DISCLAIMS 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: lock.s,v $
* Revision 2.5 91/05/14 17:57:20 mrt
* Correcting copyright
*
* Revision 2.4 91/05/08 13:36:15 dbg
* Unlock lock with a locked instruction (xchg).
* [91/03/20 dbg]
*
* Revision 2.3 91/02/14 14:20:18 mrt
* Changed to new Mach copyright
* [91/02/13 12:20:06 mrt]
*
* Revision 2.2 90/05/03 15:54:59 dbg
* Created.
* [90/02/05 dbg]
*
*/
#include <i386/asm.h>
/*
* boolean_t spin_try_lock(int *m)
*/
ENTRY(spin_try_lock)
movl 4(%esp),%ecx / point at mutex
movl $1,%eax / set locked value in acc
xchg %eax,(%ecx) / swap with mutex
/ xchg with memory is automatically
/ locked
xorl $1,%eax / 1 (locked) => FALSE
/ 0 (locked) => TRUE
ret
/*
* void spin_unlock(int *m)
*/
ENTRY(spin_unlock)
movl 4(%esp),%ecx / point at mutex
xorl %eax,%eax / set unlocked value in acc
xchg %eax,(%ecx) / swap with mutex
/ xchg with memory is automatically
/ locked
ret
|
