diff options
Diffstat (limited to 'src/libstd')
| -rw-r--r-- | src/libstd/num/mod.rs | 6 |
1 files changed, 6 insertions, 0 deletions
diff --git a/src/libstd/num/mod.rs b/src/libstd/num/mod.rs index 12befed743a..b21a80cfd23 100644 --- a/src/libstd/num/mod.rs +++ b/src/libstd/num/mod.rs @@ -311,6 +311,12 @@ pub fn next_power_of_two<T: Unsigned + Int>(n: T) -> T { tmp + one() } +// Returns `true` iff `n == 2^k` for some k. +#[inline] +pub fn is_power_of_two<T: Unsigned + Int>(n: T) -> bool { + (n - one()) & n == zero() +} + /// Returns the smallest power of 2 greater than or equal to `n`. If the next /// power of two is greater than the type's maximum value, `None` is returned, /// otherwise the power of 2 is wrapped in `Some`. |