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      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