/*

 * // Copyright (c) Radzivon Bartoshyk 9/2025. All rights reserved.

 * //

 * // Redistribution and use in source and binary forms, with or without modification,

 * // are permitted provided that the following conditions are met:

 * //

 * // 1.  Redistributions of source code must retain the above copyright notice, this

 * // list of conditions and the following disclaimer.

 * //

 * // 2.  Redistributions in binary form must reproduce the above copyright notice,

 * // this list of conditions and the following disclaimer in the documentation

 * // and/or other materials provided with the distribution.

 * //

 * // 3.  Neither the name of the copyright holder nor the names of its

 * // contributors may be used to endorse or promote products derived from

 * // this software without specific prior written permission.

 * //

 * // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"

 * // AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE

 * // IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE

 * // DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE

 * // FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL

 * // DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR

 * // SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER

 * // CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,

 * // OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE

 * // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

 */

use crate::common::EXP_MASK_F32;

/// Hypot function

///

/// Max ULP 0.5

#[inline]

pub fn f_hypotf(x: f32, y: f32) -> f32 {

    let x_abs = f32::from_bits(x.to_bits() & 0x7fff_ffffu32);

    let y_abs = f32::from_bits(y.to_bits() & 0x7fff_ffffu32);

    let a_bits = x_abs.to_bits().max(y_abs.to_bits());

    let b_bits = x_abs.to_bits().min(y_abs.to_bits());

    let a_u = a_bits;

    let b_u = b_bits;

    if a_u >= EXP_MASK_F32 {

        // x or y is inf or nan

        if f32::from_bits(a_bits).is_nan() || f32::from_bits(b_bits).is_nan() {

            return f32::NAN;

        }

        if f32::from_bits(a_bits).is_infinite() || f32::from_bits(b_bits).is_infinite() {

            return f32::INFINITY;

        }

        return f32::from_bits(a_bits);

    }

    if a_u.wrapping_sub(b_u) >= ((23u32 + 2) << 23) {

        return x_abs + y_abs;

    }

    #[cfg(any(

        all(

            any(target_arch = "x86", target_arch = "x86_64"),

            target_feature = "fma"

        ),

        target_arch = "aarch64"

    ))]

    {

        let ad = x as f64;

        let bd = y as f64;

        use crate::common::f_fmla;

        // for FMA environment we're using Kahan style summation which is short and reliable.

        let w = bd * bd; // RN(bc)

        let e = f_fmla(-bd, bd, w); // RN(w − bc)

        let f = f_fmla(ad, ad, w); // RN(ad + w)

        let r = e + f; // RN(f + e)

        let hyp = r.sqrt(); // sqrt(x^2 + y^2)

        hyp as f32

    }

    #[cfg(not(any(

        all(

            any(target_arch = "x86", target_arch = "x86_64"),

            target_feature = "fma"

        ),

        target_arch = "aarch64"

    )))]

    {

        let ad = f32::from_bits(a_bits) as f64;

        let bd = f32::from_bits(b_bits) as f64;

        use crate::double_double::DoubleDouble;

        let dy2 = DoubleDouble::from_exact_mult(bd, bd);

        let fdx = DoubleDouble::from_exact_mult(ad, ad);

        // elements are always sorted thus fdx.hi > dy2.hi, thus fasttwosum requirements is fulfilled

        let f = DoubleDouble::add_f64(fdx, dy2.hi).to_f64();

        let r = dy2.lo + f;

        let cath = r.sqrt();

        cath as f32

    }

}

Unexecuted instantiation: pxfm::triangle::hypotf::f_hypotf

Unexecuted instantiation: pxfm::triangle::hypotf::f_hypotf

#[cfg(test)]

mod tests {

    use super::*;

    #[test]

    fn test_hypotf() {

        assert_eq!(

            f_hypotf(

                0.000000000000000000000000000000000000000091771,

                0.000000000000000000000000000000000000011754585

            ),

            0.000000000000000000000000000000000000011754944

        );

        assert_eq!(

            f_hypotf(9.177e-41, 1.1754585e-38),

            0.000000000000000000000000000000000000011754944

        );

        let dx = (f_hypotf(1f32, 1f32) - (1f32 * 1f32 + 1f32 * 1f32).sqrt()).abs();

        assert!(dx < 1e-5);

        let dx = (f_hypotf(5f32, 5f32) - (5f32 * 5f32 + 5f32 * 5f32).sqrt()).abs();

        assert!(dx < 1e-5);

    }

    #[test]

    fn test_hypotf_edge_cases() {

        assert_eq!(f_hypotf(-1.0, -3.0), 3.1622777);

        assert_eq!(f_hypotf(0.0, 0.0), 0.0);

        assert_eq!(f_hypotf(f32::INFINITY, 0.0), f32::INFINITY);

        assert_eq!(f_hypotf(0.0, f32::INFINITY), f32::INFINITY);

        assert_eq!(f_hypotf(f32::INFINITY, f32::INFINITY), f32::INFINITY);

        assert_eq!(f_hypotf(f32::NEG_INFINITY, 0.0), f32::INFINITY);

        assert_eq!(f_hypotf(0.0, f32::NEG_INFINITY), f32::INFINITY);

        assert_eq!(

            f_hypotf(f32::NEG_INFINITY, f32::NEG_INFINITY),

            f32::INFINITY

        );

        assert!(f_hypotf(f32::NAN, 1.0).is_nan());

        assert!(f_hypotf(1.0, f32::NAN).is_nan());

    }

}