buddyalloc/
math.rs

1/// Calculate the base-2 logarithm of this value.
2///
3/// This will normally round down, except for the case of `0.log2()`,
4/// which will return 0.
5///
6/// Based on the obvious code at
7/// http://graphics.stanford.edu/~seander/bithacks.html#IntegerLogObvious
8pub const fn log2(n: usize) -> u8 {
9    let mut temp = n;
10    let mut result = 0;
11    temp >>= 1;
12    while temp != 0 {
13        result += 1;
14        temp >>= 1;
15    }
16    result
17}
18
19#[test]
20fn test_log2() {
21    assert_eq!(0, log2(0));
22    assert_eq!(0, log2(1));
23    assert_eq!(1, log2(2));
24    assert_eq!(5, log2(32));
25    assert_eq!(10, log2(1024));
26}
buddyalloc/math.rs

buddyalloc/
math.rs
