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use core::f64;

const TOINT: f64 = 1. / f64::EPSILON;

#[inline]
pub fn floor(x: f64) -> f64 {
    let ui = x.to_bits();
    let e = ((ui >> 52) & 0x7ff) as i32;

    if (e >= 0x3ff + 52) || (x == 0.) {
        return x;
    }
    /* y = int(x) - x, where int(x) is an integer neighbor of x */
    let y = if (ui >> 63) != 0 {
        x - TOINT + TOINT - x
    } else {
        x + TOINT - TOINT - x
    };
    /* special case because of non-nearest rounding modes */
    if e <= 0x3ff - 1 {
        force_eval!(y);
        return if (ui >> 63) != 0 { -1. } else { 0. };
    }
    if y > 0. {
        x + y - 1.
    } else {
        x + y
    }
}