const FP_ILOGBNAN: i32 = -1 - 0x7fffffff;

const FP_ILOGB0: i32 = FP_ILOGBNAN;

#[cfg_attr(all(test, assert_no_panic), no_panic::no_panic)]

pub fn ilogbf(x: f32) -> i32 {

    let mut i = x.to_bits();

    let e = ((i >> 23) & 0xff) as i32;

    if e == 0 {

        i <<= 9;

        if i == 0 {

            force_eval!(0.0 / 0.0);

            return FP_ILOGB0;

        }

        /* subnormal x */

        let mut e = -0x7f;

        while (i >> 31) == 0 {

            e -= 1;

            i <<= 1;

        }

        e

    } else if e == 0xff {

        force_eval!(0.0 / 0.0);

        if (i << 9) != 0 { FP_ILOGBNAN } else { i32::max_value() }

    } else {

        e - 0x7f

    }

}