1#[cfg_attr(all(test, assert_no_panic), no_panic::no_panic)]
2pub fn rint(x: f64) -> f64 {
3 let one_over_e = 1.0 / f64::EPSILON;
4 let as_u64: u64 = x.to_bits();
5 let exponent: u64 = as_u64 >> 52 & 0x7ff;
6 let is_positive = (as_u64 >> 63) == 0;
7 if exponent >= 0x3ff + 52 {
8 x
9 } else {
10 let ans = if is_positive {
11 #[cfg(all(target_arch = "x86", not(target_feature = "sse2")))]
12 let x = force_eval!(x);
13 let xplusoneovere = x + one_over_e;
14 #[cfg(all(target_arch = "x86", not(target_feature = "sse2")))]
15 let xplusoneovere = force_eval!(xplusoneovere);
16 xplusoneovere - one_over_e
17 } else {
18 #[cfg(all(target_arch = "x86", not(target_feature = "sse2")))]
19 let x = force_eval!(x);
20 let xminusoneovere = x - one_over_e;
21 #[cfg(all(target_arch = "x86", not(target_feature = "sse2")))]
22 let xminusoneovere = force_eval!(xminusoneovere);
23 xminusoneovere + one_over_e
24 };
25
26 if ans == 0.0 {
27 if is_positive {
28 0.0
29 } else {
30 -0.0
31 }
32 } else {
33 ans
34 }
35 }
36}
37
38// PowerPC tests are failing on LLVM 13: https://github.com/rust-lang/rust/issues/88520
39#[cfg(not(target_arch = "powerpc64"))]
40#[cfg(test)]
41mod tests {
42 use super::rint;
43
44 #[test]
45 fn negative_zero() {
46 assert_eq!(rint(-0.0_f64).to_bits(), (-0.0_f64).to_bits());
47 }
48
49 #[test]
50 fn sanity_check() {
51 assert_eq!(rint(-1.0), -1.0);
52 assert_eq!(rint(2.8), 3.0);
53 assert_eq!(rint(-0.5), -0.0);
54 assert_eq!(rint(0.5), 0.0);
55 assert_eq!(rint(-1.5), -2.0);
56 assert_eq!(rint(1.5), 2.0);
57 }
58}
59