diff options
Diffstat (limited to 'include/linux/mman.h')
| -rw-r--r-- | include/linux/mman.h | 9 |
1 files changed, 7 insertions, 2 deletions
diff --git a/include/linux/mman.h b/include/linux/mman.h index cfb6ac61bbde..07da84fcbd15 100644 --- a/include/linux/mman.h +++ b/include/linux/mman.h @@ -28,8 +28,13 @@ static inline void vm_unacct_memory(long pages) vm_acct_memory(-pages); } -/* Optimisation macro. */ -#define _calc_vm_trans(x,bit1,bit2) \ +/* + * Optimisation macro. It is equivalent to: + * (x & bit1) ? bit2 : 0 + * but this version is faster. + * ("bit1" and "bit2" must be single bits) + */ +#define _calc_vm_trans(x, bit1, bit2) \ ((bit1) <= (bit2) ? ((x) & (bit1)) * ((bit2) / (bit1)) \ : ((x) & (bit1)) / ((bit1) / (bit2))) |