kernel-ark/include/asm-generic/bitops.h
Linus Torvalds 1da177e4c3 Linux-2.6.12-rc2
Initial git repository build. I'm not bothering with the full history,
even though we have it. We can create a separate "historical" git
archive of that later if we want to, and in the meantime it's about
3.2GB when imported into git - space that would just make the early
git days unnecessarily complicated, when we don't have a lot of good
infrastructure for it.

Let it rip!
2005-04-16 15:20:36 -07:00

82 lines
1.8 KiB
C

#ifndef _ASM_GENERIC_BITOPS_H_
#define _ASM_GENERIC_BITOPS_H_
/*
* 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 assembly 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 longs.
* 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,long * 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, long * 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, const unsigned long * addr)
{
int mask;
addr += nr >> 5;
mask = 1 << (nr & 0x1f);
return ((mask & *addr) != 0);
}
/*
* fls: find last bit set.
*/
#define fls(x) generic_fls(x)
#ifdef __KERNEL__
/*
* ffs: find first bit set. This is defined the same way as
* the libc and compiler builtin ffs routines, therefore
* differs in spirit from the above ffz (man ffs).
*/
#define ffs(x) generic_ffs(x)
/*
* hweightN: returns the hamming weight (i.e. the number
* of bits set) of a N-bit word
*/
#define hweight32(x) generic_hweight32(x)
#define hweight16(x) generic_hweight16(x)
#define hweight8(x) generic_hweight8(x)
#endif /* __KERNEL__ */
#endif /* _ASM_GENERIC_BITOPS_H */