pxfm 0.1.4

/*
 * // Copyright (c) Radzivon Bartoshyk 6/2025. 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::{f_fmla, f_fmlaf};

static TB: [u64; 32] = [
    0x3fe0000000000000,
    0x3fe059b0d3158574,
    0x3fe0b5586cf9890f,
    0x3fe11301d0125b51,
    0x3fe172b83c7d517b,
    0x3fe1d4873168b9aa,
    0x3fe2387a6e756238,
    0x3fe29e9df51fdee1,
    0x3fe306fe0a31b715,
    0x3fe371a7373aa9cb,
    0x3fe3dea64c123422,
    0x3fe44e086061892d,
    0x3fe4bfdad5362a27,
    0x3fe5342b569d4f82,
    0x3fe5ab07dd485429,
    0x3fe6247eb03a5585,
    0x3fe6a09e667f3bcd,
    0x3fe71f75e8ec5f74,
    0x3fe7a11473eb0187,
    0x3fe82589994cce13,
    0x3fe8ace5422aa0db,
    0x3fe93737b0cdc5e5,
    0x3fe9c49182a3f090,
    0x3fea5503b23e255d,
    0x3feae89f995ad3ad,
    0x3feb7f76f2fb5e47,
    0x3fec199bdd85529c,
    0x3fecb720dcef9069,
    0x3fed5818dcfba487,
    0x3fedfc97337b9b5f,
    0x3feea4afa2a490da,
    0x3fef50765b6e4540,
];

/// Huperbolic sine function
///
/// Max found ULP 0.4954563
#[inline]
pub fn f_sinhf(x: f32) -> f32 {
    const C: [u64; 4] = [
        0x3ff0000000000000,
        0x3f962e42fef4c4e7,
        0x3f2ebfd1b232f475,
        0x3ebc6b19384ecd93,
    ];
    const CH: [u64; 7] = [
        0x3ff0000000000000,
        0x3f962e42fefa39ef,
        0x3f2ebfbdff82c58f,
        0x3ebc6b08d702e0ed,
        0x3e43b2ab6fb92e5e,
        0x3dc5d886e6d54203,
        0x3d4430976b8ce6ef,
    ];

    const ST: [(u32, u32, u32); 1] = [(0x74250bfeu32, 0x3a1285ff, 0x2d800000)];
    const ILN2: f64 = f64::from_bits(0x40471547652b82fe);
    let t = x.to_bits();
    let z: f64 = x as f64;
    let ux = t.wrapping_shl(1);
    if ux > 0x8565a9f8u32 {
        // |x| > 89.416
        let sgn = f32::copysign(2.0, x);
        if ux >= 0xff000000u32 {
            if ux.wrapping_shl(8) != 0 {
                return x + x;
            } // nan
            return sgn * f32::INFINITY; // +-inf
        }
        let r = sgn * f64::from_bits(0x47efffffe0000000) as f32;

        return r;
    }
    if ux < 0x7c000000u32 {
        // |x| < 0.125
        if ux <= 0x74250bfeu32 {
            // |x| <= 0.000558942
            if ux < 0x66000000u32 {
                // |x| < 5.96046e-08
                return f_fmlaf(x, x.abs(), x);
            }
            if ST[0].0 == ux {
                let sgn = f32::copysign(1.0, x);
                return f_fmlaf(sgn, f32::from_bits(ST[0].1), sgn * f32::from_bits(ST[0].2));
            }
            return f_fmlaf(x * f64::from_bits(0x3fc5555560000000) as f32, x * x, x);
        }
        const CP: [u64; 4] = [
            0x3fc5555555555555,
            0x3f811111111146e1,
            0x3f2a01a00930dda6,
            0x3ec71f92198aa6e9,
        ];
        let z2 = z * z;
        let z4 = z2 * z2;

        let w0 = f_fmla(z2, f64::from_bits(CP[3]), f64::from_bits(CP[2]));
        let w1 = f_fmla(z2, f64::from_bits(CP[1]), f64::from_bits(CP[0]));
        let w2 = f_fmla(z4, w0, w1);

        return f_fmla(z2 * z, w2, z) as f32;
    }
    let a = ILN2 * z;
    let ia = a.round_ties_even();
    let mut h = a - ia;
    let mut h2 = h * h;
    let ja = (ia + f64::from_bits(0x4338000000000000)).to_bits();
    let jp: i64 = ja as i64;
    let jm = -jp;
    let sp = TB[(jp & 31) as usize].wrapping_add(jp.wrapping_shr(5).wrapping_shl(52) as u64);
    let sm = TB[(jm & 31) as usize].wrapping_add(jm.wrapping_shr(5).wrapping_shl(52) as u64);
    let mut te = f_fmla(h2, f64::from_bits(C[2]), f64::from_bits(C[0]));
    let mut to = f_fmla(h2, f64::from_bits(C[3]), f64::from_bits(C[1]));
    let rp = f64::from_bits(sp) * f_fmla(h, to, te);
    let rm = f64::from_bits(sm) * f_fmla(-h, to, te);
    let mut r = rp - rm;
    let mut ub = r;
    let lb = r - f64::from_bits(0x3de4e406496685f4) * r;
    // Ziv's accuracy test
    if ub != lb {
        const ILN2H: f64 = f64::from_bits(0x4047154765000000);
        const ILN2L: f64 = f64::from_bits(0x3e55c17f0bbbe880);
        h = f_fmla(ILN2L, z, f_fmla(ILN2H, z, -ia));
        h2 = h * h;

        let q0 = f_fmla(h2, f64::from_bits(CH[6]), f64::from_bits(CH[4]));
        let q1 = f_fmla(h2, f64::from_bits(CH[2]), f64::from_bits(CH[0]));

        te = f_fmla(h2 * h2, q0, q1);

        let q2 = f_fmla(h2, f64::from_bits(CH[5]), f64::from_bits(CH[3]));

        to = f_fmla(h2, q2, f64::from_bits(CH[1]));

        let b0 = f_fmla(h, to, te);
        let b1 = f_fmla(-h, to, te);

        r = f_fmla(f64::from_bits(sp), b0, -f64::from_bits(sm) * b1);
        ub = r;
    }
    ub as f32
}

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn test_sinhf() {
        assert_eq!(f_sinhf(-0.5), -0.5210953);
        assert_eq!(f_sinhf(0.5), 0.5210953);
        assert_eq!(f_sinhf(7.), 548.3161);
    }
}