| use core::f64; |
| |
| const TOINT: f64 = 1.0 / f64::EPSILON; |
| |
| #[cfg_attr(all(test, assert_no_panic), no_panic::no_panic)] |
| pub fn round(mut x: f64) -> f64 { |
| let i = x.to_bits(); |
| let e: u64 = i >> 52 & 0x7ff; |
| let mut y: f64; |
| |
| if e >= 0x3ff + 52 { |
| return x; |
| } |
| if e < 0x3ff - 1 { |
| // raise inexact if x!=0 |
| force_eval!(x + TOINT); |
| return 0.0 * x; |
| } |
| if i >> 63 != 0 { |
| x = -x; |
| } |
| y = x + TOINT - TOINT - x; |
| if y > 0.5 { |
| y = y + x - 1.0; |
| } else if y <= -0.5 { |
| y = y + x + 1.0; |
| } else { |
| y = y + x; |
| } |
| |
| if i >> 63 != 0 { |
| -y |
| } else { |
| y |
| } |
| } |
| |
| #[cfg(test)] |
| mod tests { |
| use super::round; |
| |
| #[test] |
| fn negative_zero() { |
| assert_eq!(round(-0.0_f64).to_bits(), (-0.0_f64).to_bits()); |
| } |
| } |