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#ifndef _ASM_BITOPS_H
#define _ASM_BITOPS_H
/*
* Copyright 1992, Linus Torvalds.
*/
#ifdef i386
/*
* These have to be done with inline assembly: that way the bit-setting
* is guaranteed to be atomic. All bitoperations return 0 if the bit
* was cleared before the operation and != 0 if it was not.
*
* bit 0 is the LSB of addr; bit 32 is the LSB of (addr+1).
*/
/*
* Some hacks to defeat gcc over-optimizations..
*/
struct __dummy { unsigned long a[100]; };
#define ADDR (*(struct __dummy *) addr)
extern __inline__ int set_bit(int nr, void * addr)
{
int oldbit;
__asm__ __volatile__("btsl %2,%1\n\tsbbl %0,%0"
:"=r" (oldbit),"=m" (ADDR)
:"r" (nr));
return oldbit;
}
extern __inline__ int clear_bit(int nr, void * addr)
{
int oldbit;
__asm__ __volatile__("btrl %2,%1\n\tsbbl %0,%0"
:"=r" (oldbit),"=m" (ADDR)
:"r" (nr));
return oldbit;
}
/*
* This routine doesn't need to be atomic, but it's faster to code it
* this way.
*/
extern __inline__ int test_bit(int nr, void * addr)
{
int oldbit;
__asm__ __volatile__("btl %2,%1\n\tsbbl %0,%0"
:"=r" (oldbit)
:"m" (ADDR),"r" (nr));
return oldbit;
}
#else
/*
* For the benefit of those who are trying to port Linux to another
* architecture, here are some C-language equivalents. You should
* recode these in the native assmebly language, if at all possible.
* To guarantee atomicity, these routines call cli() and sti() to
* disable interrupts while they operate. (You have to provide inline
* routines to cli() and sti().)
*
* Also note, these routines assume that you have 32 bit integers.
* You will have to change this if you are trying to port Linux to the
* Alpha architecture or to a Cray. :-)
*
* C language equivalents written by Theodore Ts'o, 9/26/92
*/
extern __inline__ int set_bit(int nr,int * addr)
{
int mask, retval;
addr += nr >> 5;
mask = 1 << (nr & 0x1f);
cli();
retval = (mask & *addr) != 0;
*addr |= mask;
sti();
return retval;
}
extern __inline__ int clear_bit(int nr, int * addr)
{
int mask, retval;
addr += nr >> 5;
mask = 1 << (nr & 0x1f);
cli();
retval = (mask & *addr) != 0;
*addr &= ~mask;
sti();
return retval;
}
extern __inline__ int test_bit(int nr, int * addr)
{
int mask;
addr += nr >> 5;
mask = 1 << (nr & 0x1f);
return ((mask & *addr) != 0);
}
#endif /* i386 */
#endif /* _ASM_BITOPS_H */