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Diffstat (limited to 'include/asm-generic/bitops.h')
-rw-r--r-- | include/asm-generic/bitops.h | 81 |
1 files changed, 81 insertions, 0 deletions
diff --git a/include/asm-generic/bitops.h b/include/asm-generic/bitops.h new file mode 100644 index 000000000000..ce31b739fd80 --- /dev/null +++ b/include/asm-generic/bitops.h @@ -0,0 +1,81 @@ +#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 */ |