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
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87

use num::arithmetic::traits::PowerOf2;
use num::basic::signeds::PrimitiveSigned;
use num::basic::unsigneds::PrimitiveUnsigned;
use num::conversion::traits::IntegerMantissaAndExponent;

fn power_of_2_unsigned<T: PrimitiveUnsigned>(pow: u64) -> T {
    assert!(pow < T::WIDTH);
    T::ONE << pow
}

macro_rules! impl_power_of_2_unsigned {
    ($t:ident) => {
        impl PowerOf2<u64> for $t {
            /// Raises 2 to an integer power.
            ///
            /// $f(k) = 2^k$.
            ///
            /// # Worst-case complexity
            /// Constant time and additional memory.
            ///
            /// # Panics
            /// Panics if the result is not representable.
            ///
            /// # Examples
            /// See [here](super::power_of_2#power_of_2).
            #[inline]
            fn power_of_2(pow: u64) -> $t {
                power_of_2_unsigned(pow)
            }
        }
    };
}
apply_to_unsigneds!(impl_power_of_2_unsigned);

fn power_of_2_signed<T: PrimitiveSigned>(pow: u64) -> T {
    assert!(pow < T::WIDTH - 1);
    T::ONE << pow
}

macro_rules! impl_power_of_2_signed {
    ($t:ident) => {
        impl PowerOf2<u64> for $t {
            /// Raises 2 to an integer power.
            ///
            /// $f(k) = 2^k$.
            ///
            /// # Worst-case complexity
            /// Constant time and additional memory.
            ///
            /// # Panics
            /// Panics if the result is not representable.
            ///
            /// # Examples
            /// See [here](super::power_of_2#power_of_2).
            #[inline]
            fn power_of_2(pow: u64) -> $t {
                power_of_2_signed(pow)
            }
        }
    };
}
apply_to_signeds!(impl_power_of_2_signed);

macro_rules! impl_power_of_2_primitive_float {
    ($t:ident) => {
        impl PowerOf2<i64> for $t {
            /// Raises 2 to an integer power.
            ///
            /// $f(k) = 2^k$.
            ///
            /// # Worst-case complexity
            /// Constant time and additional memory.
            ///
            /// # Panics
            /// Panics if the power is smaller than `Self::MIN_EXPONENT` or greater than
            /// `Self::MAX_EXPONENT`.
            ///
            /// # Examples
            /// See [here](super::power_of_2#power_of_2).
            #[inline]
            fn power_of_2(pow: i64) -> $t {
                $t::from_integer_mantissa_and_exponent(1, pow).unwrap()
            }
        }
    };
}
apply_to_primitive_floats!(impl_power_of_2_primitive_float);