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#[cfg_attr(all(test, assert_no_panic), no_panic::no_panic)]
pub fn rint(x: f64) -> f64 {
let one_over_e = 1.0 / f64::EPSILON;
let as_u64: u64 = x.to_bits();
let exponent: u64 = as_u64 >> 52 & 0x7ff;
let is_positive = (as_u64 >> 63) == 0;
if exponent >= 0x3ff + 52 {
x
} else {
let ans = if is_positive {
x + one_over_e - one_over_e
} else {
x - one_over_e + one_over_e
};
if ans == 0.0 {
if is_positive {
0.0
} else {
-0.0
}
} else {
ans
}
}
}
#[cfg(not(target_arch = "powerpc64"))]
#[cfg(test)]
mod tests {
use super::rint;
#[test]
fn negative_zero() {
assert_eq!(rint(-0.0_f64).to_bits(), (-0.0_f64).to_bits());
}
#[test]
fn sanity_check() {
assert_eq!(rint(-1.0), -1.0);
assert_eq!(rint(2.8), 3.0);
assert_eq!(rint(-0.5), -0.0);
assert_eq!(rint(0.5), 0.0);
assert_eq!(rint(-1.5), -2.0);
assert_eq!(rint(1.5), 2.0);
}
}