1 #ifndef _ARCH_ATOMIC_X86_H
2 #define _ARCH_ATOMIC_X86_H
5 * Copyright (c) 1991-1994 by Xerox Corporation. All rights reserved.
6 * Copyright (c) 1996-1999 by Silicon Graphics. All rights reserved.
7 * Copyright (c) 1999-2004 Hewlett-Packard Development Company, L.P.
8 * Copyright (c) 2009 Mathieu Desnoyers
10 * THIS MATERIAL IS PROVIDED AS IS, WITH ABSOLUTELY NO WARRANTY EXPRESSED
11 * OR IMPLIED. ANY USE IS AT YOUR OWN RISK.
13 * Permission is hereby granted to use or copy this program
14 * for any purpose, provided the above notices are retained on all copies.
15 * Permission to modify the code and to distribute modified code is granted,
16 * provided the above notices are retained, and a notice that the code was
17 * modified is included with the above copyright notice.
19 * Code inspired from libatomic_ops-1.2, inherited in part from the
20 * Boehm-Demers-Weiser conservative garbage collector.
24 #define BITS_PER_LONG (__SIZEOF_LONG__ * 8)
27 #ifndef _INCLUDE_API_H
30 * Derived from AO_compare_and_swap() and AO_test_and_set_full().
33 static inline __attribute__((always_inline
))
34 unsigned int atomic_exchange_32(volatile unsigned int *addr
, unsigned int val
)
39 /* Note: the "xchg" instruction does not need a "lock" prefix */
41 : "=&r"(result
), "=m"(*addr
)
42 : "0" (val
), "m"(*addr
)
48 #if (BITS_PER_LONG == 64)
50 static inline __attribute__((always_inline
))
51 unsigned long atomic_exchange_64(volatile unsigned long *addr
,
57 /* Note: the "xchg" instruction does not need a "lock" prefix */
59 : "=&r"(result
), "=m"(*addr
)
60 : "0" (val
), "m"(*addr
)
68 static inline __attribute__((always_inline
))
69 unsigned long _atomic_exchange(volatile void *addr
, unsigned long val
, int len
)
72 case 4: return atomic_exchange_32(addr
, val
);
73 #if (BITS_PER_LONG == 64)
74 case 8: return atomic_exchange_64(addr
, val
);
77 /* generate an illegal instruction. Cannot catch this with linker tricks
78 * when optimizations are disabled. */
79 __asm__
__volatile__("ud2");
83 #define xchg(addr, v) \
84 ((__typeof__(*(addr))) _atomic_exchange((addr), (unsigned long)(v), \
87 #endif /* #ifndef _INCLUDE_API_H */
89 #endif /* ARCH_ATOMIC_X86_H */
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