diff options
Diffstat (limited to 'include/asm-generic/bitops.h')
| -rw-r--r-- | include/asm-generic/bitops.h | 53 |
1 files changed, 53 insertions, 0 deletions
diff --git a/include/asm-generic/bitops.h b/include/asm-generic/bitops.h new file mode 100644 index 000000000..130619840 --- /dev/null +++ b/include/asm-generic/bitops.h @@ -0,0 +1,53 @@ +#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 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 /* _ASM_GENERIC_BITOPS_H */ |