1 #ifndef _ASM_GENERIC_BITOPS_NON_ATOMIC_H_
2 #define _ASM_GENERIC_BITOPS_NON_ATOMIC_H_
3 
4 #include <asm/types.h>
5 
6 #define BITOP_MASK(nr)		(1UL << ((nr) % BITS_PER_LONG))
7 #define BITOP_WORD(nr)		((nr) / BITS_PER_LONG)
8 
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);
22 
23 	*p  |= mask;
24 }
25 
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);
30 
31 	*p &= ~mask;
32 }
33 
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);
47 
48 	*p ^= mask;
49 }
50 
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;
65 
66 	*p = old | mask;
67 	return (old & mask) != 0;
68 }
69 
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;
84 
85 	*p = old & ~mask;
86 	return (old & mask) != 0;
87 }
88 
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;
96 
97 	*p = old ^ mask;
98 	return (old & mask) != 0;
99 }
100 
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 }
110 
111 #endif /* _ASM_GENERIC_BITOPS_NON_ATOMIC_H_ */
112