1/* SPDX-License-Identifier: MIT OR Apache-2.0 */
2//! IEEE 754-2008 `minNum`. This has been superseded by IEEE 754-2019 `minimumNumber`.
3//!
4//! Per the spec, returns the canonicalized result of:
5//! - `x` if `x < y`
6//! - `y` if `y < x`
7//! - The other number if one is NaN
8//! - Otherwise, either `x` or `y`, canonicalized
9//! - -0.0 and +0.0 may be disregarded (unlike newer operations)
10//!
11//! Excluded from our implementation is sNaN handling.
12//!
13//! More on the differences: [link].
14//!
15//! [link]: https://grouper.ieee.org/groups/msc/ANSI_IEEE-Std-754-2019/background/minNum_maxNum_Removal_Demotion_v3.pdf
16
17use super::super::Float;
18
19pub fn fmin<F: Float>(x: F, y: F) -> F {
20 let res: F = if y.is_nan() || x < y { x } else { y };
21 // Canonicalize
22 res * F::ONE
23}
24
25#[cfg(test)]
26mod tests {
27 use super::*;
28 use crate::support::{Hexf, Int};
29
30 fn spec_test<F: Float>() {
31 let cases = [
32 (F::ZERO, F::ZERO, F::ZERO),
33 (F::ONE, F::ONE, F::ONE),
34 (F::ZERO, F::ONE, F::ZERO),
35 (F::ONE, F::ZERO, F::ZERO),
36 (F::ZERO, F::NEG_ONE, F::NEG_ONE),
37 (F::NEG_ONE, F::ZERO, F::NEG_ONE),
38 (F::INFINITY, F::ZERO, F::ZERO),
39 (F::NEG_INFINITY, F::ZERO, F::NEG_INFINITY),
40 (F::NAN, F::ZERO, F::ZERO),
41 (F::ZERO, F::NAN, F::ZERO),
42 (F::NAN, F::NAN, F::NAN),
43 ];
44
45 for (x, y, res) in cases {
46 let val = fmin(x, y);
47 assert_biteq!(val, res, "fmin({}, {})", Hexf(x), Hexf(y));
48 }
49 }
50
51 #[test]
52 #[cfg(f16_enabled)]
53 fn spec_tests_f16() {
54 spec_test::<f16>();
55 }
56
57 #[test]
58 fn spec_tests_f32() {
59 spec_test::<f32>();
60 }
61
62 #[test]
63 fn spec_tests_f64() {
64 spec_test::<f64>();
65 }
66
67 #[test]
68 #[cfg(f128_enabled)]
69 fn spec_tests_f128() {
70 spec_test::<f128>();
71 }
72}
73