vendor/compiler_builtins/libm/src/math/round.rs

   1 use core::f64;
   2
   3 const TOINT: f64 = 1.0 / f64::EPSILON;
   4
   5 #[inline]
   6 pub fn round(mut x: f64) -> f64 {
   7     let (f, i) = (x, x.to_bits());
   8     let e: u64 = i >> 52 & 0x7ff;
   9     let mut y: f64;
  10
  11     if e >= 0x3ff + 52 {
  12         return x;
  13     }
  14     if i >> 63 != 0 {
  15         x = -x;
  16     }
  17     if e < 0x3ff - 1 {
  18         // raise inexact if x!=0
  19         force_eval!(x + TOINT);
  20         return 0.0 * f;
  21     }
  22     y = x + TOINT - TOINT - x;
  23     if y > 0.5 {
  24         y = y + x - 1.0;
  25     } else if y <= -0.5 {
  26         y = y + x + 1.0;
  27     } else {
  28         y = y + x;
  29     }
  30
  31     if i >> 63 != 0 {
  32         -y
  33     } else {
  34         y
  35     }
  36 }