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comparison src/atomic/SDL_spinlock.c @ 5003:3a95a2b93eb3

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Updated the atomic API for better use cases
author Sam Lantinga <slouken@libsdl.org>
date Sat, 15 Jan 2011 12:41:59 -0800
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children 0c72ae7b7cb2
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5002:c5b9486688ce 5003:3a95a2b93eb3
1 /*
2 SDL - Simple DirectMedia Layer
3 Copyright (C) 1997-2010 Sam Lantinga
4
5 This library is free software; you can redistribute it and/or
6 modify it under the terms of the GNU Lesser General Public
7 License as published by the Free Software Foundation; either
8 version 2.1 of the License, or (at your option) any later version.
9
10 This library is distributed in the hope that it will be useful,
11 but WITHOUT ANY WARRANTY; without even the implied warranty of
12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
13 Lesser General Public License for more details.
14
15 You should have received a copy of the GNU Lesser General Public
16 License along with this library; if not, write to the Free Software
17 Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
18
19 Sam Lantinga
20 slouken@libsdl.org
21 */
22 #include "SDL_stdinc.h"
23
24 #include "SDL_atomic.h"
25 #include "SDL_timer.h"
26
27 #if defined(__WIN32__)
28 #define WIN32_LEAN_AND_MEAN
29 #include <windows.h>
30
31 #elif defined(__MACOSX__)
32 #include <libkern/OSAtomic.h>
33
34 #endif
35
36
37 /* This function is where all the magic happens... */
38 SDL_bool
39 SDL_AtomicTryLock(SDL_SpinLock *lock)
40 {
41 #if defined(__WIN32__)
42 return (InterlockedExchange(lock, 1) == 0);
43
44 #elif defined(__MACOSX__)
45 return OSAtomicCompareAndSwap32Barrier(0, 1, lock);
46
47 #elif defined(__GNUC__)
48 #if defined(__arm__)
49 #ifdef __ARM_ARCH_5__
50 int result;
51 __asm__ __volatile__ (
52 "swp %0, %1, [%2]\n"
53 : "=&r,&r" (result) : "r,0" (1), "r,r" (lock) : "memory");
54 return (result == 0);
55 #else
56 int result;
57 __asm__ __volatile__ (
58 "ldrex %0, [%2]\nteq %0, #0\nstrexeq %0, %1, [%2]"
59 : "=&r" (result) : "r" (1), "r" (lock) : "cc", "memory");
60 return (result == 0);
61 #endif
62 #else
63 return (__sync_lock_test_and_set(lock, 1) == 0);
64 #endif
65
66 #else
67 /* Need CPU instructions for spinlock here! */
68 __need_spinlock_implementation__
69 #endif
70 }
71
72 void
73 SDL_AtomicLock(SDL_SpinLock *lock)
74 {
75 /* FIXME: Should we have an eventual timeout? */
76 while (!SDL_AtomicTryLock(lock)) {
77 SDL_Delay(0);
78 }
79 }
80
81 void
82 SDL_AtomicUnlock(SDL_SpinLock *lock)
83 {
84 #if defined(__WIN32__)
85 *lock = 0;
86
87 #elif defined(__MACOSX__)
88 *lock = 0;
89
90 #elif defined(__GNUC__) && !defined(__arm__)
91 __sync_lock_release(lock);
92
93 #else
94 /* Assuming memory barrier in lock and integral assignment operation */
95 *lock = 0;
96 #endif
97 }
98
99 /* vi: set ts=4 sw=4 expandtab: */