1 #[cfg_attr(all(test, assert_no_panic), no_panic::no_panic)]
rint(x: f64) -> f642 pub 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 { if is_positive { 0.0 } else { -0.0 } } else { ans }
27 }
28 }
29
30 // PowerPC tests are failing on LLVM 13: https://github.com/rust-lang/rust/issues/88520
31 #[cfg(not(target_arch = "powerpc64"))]
32 #[cfg(test)]
33 mod tests {
34 use super::rint;
35
36 #[test]
negative_zero()37 fn negative_zero() {
38 assert_eq!(rint(-0.0_f64).to_bits(), (-0.0_f64).to_bits());
39 }
40
41 #[test]
sanity_check()42 fn sanity_check() {
43 assert_eq!(rint(-1.0), -1.0);
44 assert_eq!(rint(2.8), 3.0);
45 assert_eq!(rint(-0.5), -0.0);
46 assert_eq!(rint(0.5), 0.0);
47 assert_eq!(rint(-1.5), -2.0);
48 assert_eq!(rint(1.5), 2.0);
49 }
50 }
51