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
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
use core::mem;
use core::ops;
use super::int::Int;
pub mod add;
pub mod cmp;
pub mod conv;
pub mod div;
pub mod extend;
pub mod mul;
pub mod pow;
pub mod sub;
pub(crate) trait Float:
Copy
+ PartialEq
+ PartialOrd
+ ops::AddAssign
+ ops::MulAssign
+ ops::Add<Output = Self>
+ ops::Sub<Output = Self>
+ ops::Div<Output = Self>
+ ops::Rem<Output = Self>
{
type Int: Int;
type SignedInt: Int;
const ZERO: Self;
const ONE: Self;
const BITS: u32;
const SIGNIFICAND_BITS: u32;
const EXPONENT_BITS: u32 = Self::BITS - Self::SIGNIFICAND_BITS - 1;
const EXPONENT_MAX: u32 = (1 << Self::EXPONENT_BITS) - 1;
const EXPONENT_BIAS: u32 = Self::EXPONENT_MAX >> 1;
const SIGN_MASK: Self::Int;
const SIGNIFICAND_MASK: Self::Int;
const IMPLICIT_BIT: Self::Int;
const EXPONENT_MASK: Self::Int;
fn repr(self) -> Self::Int;
fn signed_repr(self) -> Self::SignedInt;
#[cfg(test)]
fn eq_repr(self, rhs: Self) -> bool;
fn from_repr(a: Self::Int) -> Self;
fn from_parts(sign: bool, exponent: Self::Int, significand: Self::Int) -> Self;
fn normalize(significand: Self::Int) -> (i32, Self::Int);
}
macro_rules! float_impl {
($ty:ident, $ity:ident, $sity:ident, $bits:expr, $significand_bits:expr) => {
impl Float for $ty {
type Int = $ity;
type SignedInt = $sity;
const ZERO: Self = 0.0;
const ONE: Self = 1.0;
const BITS: u32 = $bits;
const SIGNIFICAND_BITS: u32 = $significand_bits;
const SIGN_MASK: Self::Int = 1 << (Self::BITS - 1);
const SIGNIFICAND_MASK: Self::Int = (1 << Self::SIGNIFICAND_BITS) - 1;
const IMPLICIT_BIT: Self::Int = 1 << Self::SIGNIFICAND_BITS;
const EXPONENT_MASK: Self::Int = !(Self::SIGN_MASK | Self::SIGNIFICAND_MASK);
fn repr(self) -> Self::Int {
unsafe { mem::transmute(self) }
}
fn signed_repr(self) -> Self::SignedInt {
unsafe { mem::transmute(self) }
}
#[cfg(test)]
fn eq_repr(self, rhs: Self) -> bool {
if self.is_nan() && rhs.is_nan() {
true
} else {
self.repr() == rhs.repr()
}
}
fn from_repr(a: Self::Int) -> Self {
unsafe { mem::transmute(a) }
}
fn from_parts(sign: bool, exponent: Self::Int, significand: Self::Int) -> Self {
Self::from_repr(
((sign as Self::Int) << (Self::BITS - 1))
| ((exponent << Self::SIGNIFICAND_BITS) & Self::EXPONENT_MASK)
| (significand & Self::SIGNIFICAND_MASK),
)
}
fn normalize(significand: Self::Int) -> (i32, Self::Int) {
let shift = significand
.leading_zeros()
.wrapping_sub((Self::Int::ONE << Self::SIGNIFICAND_BITS).leading_zeros());
(
1i32.wrapping_sub(shift as i32),
significand << shift as Self::Int,
)
}
}
};
}
float_impl!(f32, u32, i32, 32, 23);
float_impl!(f64, u64, i64, 64, 52);