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/*
This file is copied from the Linux kernel and mildly adjusted for use in userspace
*/
#ifndef _ASM_GENERIC_BITOPS_NON_ATOMIC_H_
#define _ASM_GENERIC_BITOPS_NON_ATOMIC_H_
#define BITOP_MASK(nr) (1UL << ((nr) % BITS_PER_LONG))
#define BITOP_WORD(nr) ((nr) / BITS_PER_LONG)
/**
* __set_bit - Set a bit in memory
* @nr: the bit to set
* @addr: the address to start counting from
*
* Unlike set_bit(), this function is non-atomic and may be reordered.
* If it's called on the same region of memory simultaneously, the effect
* may be that only one operation succeeds.
*/
static inline void set_bit(int nr, volatile unsigned long *addr)
{
unsigned long mask = BITOP_MASK(nr);
unsigned long *p = ((unsigned long *)addr) + BITOP_WORD(nr);
*p |= mask;
}
static inline void clear_bit(int nr, volatile unsigned long *addr)
{
unsigned long mask = BITOP_MASK(nr);
unsigned long *p = ((unsigned long *)addr) + BITOP_WORD(nr);
*p &= ~mask;
}
/**
* __change_bit - Toggle a bit in memory
* @nr: the bit to change
* @addr: the address to start counting from
*
* Unlike change_bit(), this function is non-atomic and may be reordered.
* If it's called on the same region of memory simultaneously, the effect
* may be that only one operation succeeds.
*/
static inline void __change_bit(int nr, volatile unsigned long *addr)
{
unsigned long mask = BITOP_MASK(nr);
unsigned long *p = ((unsigned long *)addr) + BITOP_WORD(nr);
*p ^= mask;
}
/**
* __test_and_set_bit - Set a bit and return its old value
* @nr: Bit to set
* @addr: Address to count from
*
* This operation is non-atomic and can be reordered.
* If two examples of this operation race, one can appear to succeed
* but actually fail. You must protect multiple accesses with a lock.
*/
static inline int __test_and_set_bit(int nr, volatile unsigned long *addr)
{
unsigned long mask = BITOP_MASK(nr);
unsigned long *p = ((unsigned long *)addr) + BITOP_WORD(nr);
unsigned long old = *p;
*p = old | mask;
return (old & mask) != 0;
}
/**
* __test_and_clear_bit - Clear a bit and return its old value
* @nr: Bit to clear
* @addr: Address to count from
*
* This operation is non-atomic and can be reordered.
* If two examples of this operation race, one can appear to succeed
* but actually fail. You must protect multiple accesses with a lock.
*/
static inline int __test_and_clear_bit(int nr, volatile unsigned long *addr)
{
unsigned long mask = BITOP_MASK(nr);
unsigned long *p = ((unsigned long *)addr) + BITOP_WORD(nr);
unsigned long old = *p;
*p = old & ~mask;
return (old & mask) != 0;
}
/* WARNING: non atomic and it can be reordered! */
static inline int __test_and_change_bit(int nr,
volatile unsigned long *addr)
{
unsigned long mask = BITOP_MASK(nr);
unsigned long *p = ((unsigned long *)addr) + BITOP_WORD(nr);
unsigned long old = *p;
*p = old ^ mask;
return (old & mask) != 0;
}
/**
* test_bit - Determine whether a bit is set
* @nr: bit number to test
* @addr: Address to start counting from
*/
static inline int test_bit(int nr, const volatile unsigned long *addr)
{
return 1UL & (addr[BITOP_WORD(nr)] >> (nr & (BITS_PER_LONG-1)));
}
#endif /* _ASM_GENERIC_BITOPS_NON_ATOMIC_H_ */