1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59

use crate::extensions::non_zero_usize_ext::NonZeroUsizeExt;
use std::fmt::Debug;
use std::num::NonZeroUsize;

/// Useful extensions.
pub trait UsizeExt: Sized + Copy + Ord + Debug {
    /// Is odd.
    #[inline(always)]
    fn is_odd(self) -> bool {
        self.to_usize() & 0b1 == 0b1
    }

    /// Round up.
    #[inline(always)]
    fn round_up_to_power_of_two(self, non_zero_power_of_two_alignment: NonZeroUsize) -> usize {
        let power_of_two = non_zero_power_of_two_alignment.get();
        let power_of_two_less_one = power_of_two - 1;

        let value = self.to_usize();

        debug_assert!(
            value.checked_add(power_of_two_less_one).is_some(),
            "non_zero_power_of_two_alignment is far too close to the maximum value of a pointer"
        );

        (value + power_of_two_less_one) & !power_of_two_less_one
    }

    /// Round down.
    #[inline(always)]
    fn round_down_to_power_of_two(self, power_of_two: NonZeroUsize) -> usize {
        let power_of_two_exponent = power_of_two.logarithm_base2();
        self.round_down_to_power_of_two_exponent(power_of_two_exponent)
    }

    /// Round down to power of two exponent.
    #[inline(always)]
    fn round_down_to_power_of_two_exponent(self, power_of_two_exponent: usize) -> usize {
        let value = self.to_usize();

        value & !((1 << power_of_two_exponent) - 1)
    }

    /// Non zero.
    #[inline(always)]
    fn non_zero(self) -> NonZeroUsize {
        NonZeroUsize::non_zero(self.to_usize())
    }

    #[doc(hidden)]
    fn to_usize(self) -> usize;
}

impl UsizeExt for usize {
    #[inline(always)]
    fn to_usize(self) -> usize {
        self
    }
}