ia64/linux-2.6.18-xen.hg

view include/asm-generic/bitops/non-atomic.h @ 782:9ab1c319531f

merge with linux-2.6.18-xen.hg
author Isaku Yamahata <yamahata@valinux.co.jp>
date Wed Jan 28 13:07:23 2009 +0900 (2009-01-28)
parents 831230e53067
children
line source
1 #ifndef _ASM_GENERIC_BITOPS_NON_ATOMIC_H_
2 #define _ASM_GENERIC_BITOPS_NON_ATOMIC_H_
4 #include <asm/types.h>
6 #define BITOP_MASK(nr) (1UL << ((nr) % BITS_PER_LONG))
7 #define BITOP_WORD(nr) ((nr) / BITS_PER_LONG)
9 /**
10 * __set_bit - Set a bit in memory
11 * @nr: the bit to set
12 * @addr: the address to start counting from
13 *
14 * Unlike set_bit(), this function is non-atomic and may be reordered.
15 * If it's called on the same region of memory simultaneously, the effect
16 * may be that only one operation succeeds.
17 */
18 static inline void __set_bit(int nr, volatile unsigned long *addr)
19 {
20 unsigned long mask = BITOP_MASK(nr);
21 unsigned long *p = ((unsigned long *)addr) + BITOP_WORD(nr);
23 *p |= mask;
24 }
26 static inline void __clear_bit(int nr, volatile unsigned long *addr)
27 {
28 unsigned long mask = BITOP_MASK(nr);
29 unsigned long *p = ((unsigned long *)addr) + BITOP_WORD(nr);
31 *p &= ~mask;
32 }
34 /**
35 * __change_bit - Toggle a bit in memory
36 * @nr: the bit to change
37 * @addr: the address to start counting from
38 *
39 * Unlike change_bit(), this function is non-atomic and may be reordered.
40 * If it's called on the same region of memory simultaneously, the effect
41 * may be that only one operation succeeds.
42 */
43 static inline void __change_bit(int nr, volatile unsigned long *addr)
44 {
45 unsigned long mask = BITOP_MASK(nr);
46 unsigned long *p = ((unsigned long *)addr) + BITOP_WORD(nr);
48 *p ^= mask;
49 }
51 /**
52 * __test_and_set_bit - Set a bit and return its old value
53 * @nr: Bit to set
54 * @addr: Address to count from
55 *
56 * This operation is non-atomic and can be reordered.
57 * If two examples of this operation race, one can appear to succeed
58 * but actually fail. You must protect multiple accesses with a lock.
59 */
60 static inline int __test_and_set_bit(int nr, volatile unsigned long *addr)
61 {
62 unsigned long mask = BITOP_MASK(nr);
63 unsigned long *p = ((unsigned long *)addr) + BITOP_WORD(nr);
64 unsigned long old = *p;
66 *p = old | mask;
67 return (old & mask) != 0;
68 }
70 /**
71 * __test_and_clear_bit - Clear a bit and return its old value
72 * @nr: Bit to clear
73 * @addr: Address to count from
74 *
75 * This operation is non-atomic and can be reordered.
76 * If two examples of this operation race, one can appear to succeed
77 * but actually fail. You must protect multiple accesses with a lock.
78 */
79 static inline int __test_and_clear_bit(int nr, volatile unsigned long *addr)
80 {
81 unsigned long mask = BITOP_MASK(nr);
82 unsigned long *p = ((unsigned long *)addr) + BITOP_WORD(nr);
83 unsigned long old = *p;
85 *p = old & ~mask;
86 return (old & mask) != 0;
87 }
89 /* WARNING: non atomic and it can be reordered! */
90 static inline int __test_and_change_bit(int nr,
91 volatile unsigned long *addr)
92 {
93 unsigned long mask = BITOP_MASK(nr);
94 unsigned long *p = ((unsigned long *)addr) + BITOP_WORD(nr);
95 unsigned long old = *p;
97 *p = old ^ mask;
98 return (old & mask) != 0;
99 }
101 /**
102 * test_bit - Determine whether a bit is set
103 * @nr: bit number to test
104 * @addr: Address to start counting from
105 */
106 static inline int test_bit(int nr, const volatile unsigned long *addr)
107 {
108 return 1UL & (addr[BITOP_WORD(nr)] >> (nr & (BITS_PER_LONG-1)));
109 }
111 #endif /* _ASM_GENERIC_BITOPS_NON_ATOMIC_H_ */