forked from Minki/linux
4117b02132
This patch introduces the C-language equivalents of the functions below: void __set_bit(int nr, volatile unsigned long *addr); void __clear_bit(int nr, volatile unsigned long *addr); void __change_bit(int nr, volatile unsigned long *addr); int __test_and_set_bit(int nr, volatile unsigned long *addr); int __test_and_clear_bit(int nr, volatile unsigned long *addr); int __test_and_change_bit(int nr, volatile unsigned long *addr); int test_bit(int nr, const volatile unsigned long *addr); In include/asm-generic/bitops/non-atomic.h This code largely copied from: asm-powerpc/bitops.h Signed-off-by: Akinobu Mita <mita@miraclelinux.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
112 lines
3.1 KiB
C
112 lines
3.1 KiB
C
#ifndef _ASM_GENERIC_BITOPS_NON_ATOMIC_H_
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#define _ASM_GENERIC_BITOPS_NON_ATOMIC_H_
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#include <asm/types.h>
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#define BITOP_MASK(nr) (1UL << ((nr) % BITS_PER_LONG))
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#define BITOP_WORD(nr) ((nr) / BITS_PER_LONG)
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/**
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* __set_bit - Set a bit in memory
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* @nr: the bit to set
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* @addr: the address to start counting from
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*
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* Unlike set_bit(), this function is non-atomic and may be reordered.
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* If it's called on the same region of memory simultaneously, the effect
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* may be that only one operation succeeds.
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*/
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static inline void __set_bit(int nr, volatile unsigned long *addr)
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{
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unsigned long mask = BITOP_MASK(nr);
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unsigned long *p = ((unsigned long *)addr) + BITOP_WORD(nr);
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*p |= mask;
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}
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static inline void __clear_bit(int nr, volatile unsigned long *addr)
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{
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unsigned long mask = BITOP_MASK(nr);
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unsigned long *p = ((unsigned long *)addr) + BITOP_WORD(nr);
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*p &= ~mask;
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}
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/**
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* __change_bit - Toggle a bit in memory
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* @nr: the bit to change
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* @addr: the address to start counting from
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*
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* Unlike change_bit(), this function is non-atomic and may be reordered.
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* If it's called on the same region of memory simultaneously, the effect
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* may be that only one operation succeeds.
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*/
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static inline void __change_bit(int nr, volatile unsigned long *addr)
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{
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unsigned long mask = BITOP_MASK(nr);
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unsigned long *p = ((unsigned long *)addr) + BITOP_WORD(nr);
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*p ^= mask;
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}
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/**
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* __test_and_set_bit - Set a bit and return its old value
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* @nr: Bit to set
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* @addr: Address to count from
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*
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* This operation is non-atomic and can be reordered.
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* If two examples of this operation race, one can appear to succeed
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* but actually fail. You must protect multiple accesses with a lock.
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*/
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static inline int __test_and_set_bit(int nr, volatile unsigned long *addr)
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{
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unsigned long mask = BITOP_MASK(nr);
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unsigned long *p = ((unsigned long *)addr) + BITOP_WORD(nr);
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unsigned long old = *p;
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*p = old | mask;
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return (old & mask) != 0;
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}
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/**
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* __test_and_clear_bit - Clear a bit and return its old value
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* @nr: Bit to clear
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* @addr: Address to count from
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*
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* This operation is non-atomic and can be reordered.
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* If two examples of this operation race, one can appear to succeed
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* but actually fail. You must protect multiple accesses with a lock.
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*/
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static inline int __test_and_clear_bit(int nr, volatile unsigned long *addr)
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{
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unsigned long mask = BITOP_MASK(nr);
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unsigned long *p = ((unsigned long *)addr) + BITOP_WORD(nr);
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unsigned long old = *p;
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*p = old & ~mask;
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return (old & mask) != 0;
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}
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/* WARNING: non atomic and it can be reordered! */
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static inline int __test_and_change_bit(int nr,
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volatile unsigned long *addr)
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{
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unsigned long mask = BITOP_MASK(nr);
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unsigned long *p = ((unsigned long *)addr) + BITOP_WORD(nr);
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unsigned long old = *p;
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*p = old ^ mask;
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return (old & mask) != 0;
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}
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/**
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* test_bit - Determine whether a bit is set
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* @nr: bit number to test
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* @addr: Address to start counting from
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*/
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static inline int test_bit(int nr, const volatile unsigned long *addr)
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{
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return 1UL & (addr[BITOP_WORD(nr)] >> (nr & (BITS_PER_LONG-1)));
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}
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#endif /* _ASM_GENERIC_BITOPS_NON_ATOMIC_H_ */
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