/*

 * // 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::polyeval::f_polyeval4;

use crate::sin_cosf::ArgumentReducer;

// Generated in SageMath:

// print("[")

// for k in range(64):

//     k = RealField(150)(k) * RealField(150).pi() / RealField(150)(32)

//     print(double_to_hex(k.tan()) + ",")

// print("];")

pub(crate) static TAN_K_PI_OVER32: [u64; 64] = [

    0x0000000000000000,

    0x3fb936bb8c5b2da2,

    0x3fc975f5e0553158,

    0x3fd36a08355c63dc,

    0x3fda827999fcef32,

    0x3fe11ab7190834ec,

    0x3fe561b82ab7f990,

    0x3fea43002ae42850,

    0x3ff0000000000000,

    0x3ff37efd8d87607e,

    0x3ff7f218e25a7461,

    0x3ffdef13b73c1406,

    0x4003504f333f9de6,

    0x400a5f59e90600dd,

    0x40141bfee2424771,

    0x40244e6c595afdcc,

    0xc950457bf6be49c7,

    0xc0244e6c595afdcc,

    0xc0141bfee2424771,

    0xc00a5f59e90600dd,

    0xc003504f333f9de6,

    0xbffdef13b73c1406,

    0xbff7f218e25a7461,

    0xbff37efd8d87607e,

    0xbff0000000000000,

    0xbfea43002ae42850,

    0xbfe561b82ab7f990,

    0xbfe11ab7190834ec,

    0xbfda827999fcef32,

    0xbfd36a08355c63dc,

    0xbfc975f5e0553158,

    0xbfb936bb8c5b2da2,

    0x369f77598338bfdf,

    0x3fb936bb8c5b2da2,

    0x3fc975f5e0553158,

    0x3fd36a08355c63dc,

    0x3fda827999fcef32,

    0x3fe11ab7190834ec,

    0x3fe561b82ab7f990,

    0x3fea43002ae42850,

    0x3ff0000000000000,

    0x3ff37efd8d87607e,

    0x3ff7f218e25a7461,

    0x3ffdef13b73c1406,

    0x4003504f333f9de6,

    0x400a5f59e90600dd,

    0x40141bfee2424771,

    0x40244e6c595afdcc,

    0xc935b1fa9e530d0a,

    0xc0244e6c595afdcc,

    0xc0141bfee2424771,

    0xc00a5f59e90600dd,

    0xc003504f333f9de6,

    0xbffdef13b73c1406,

    0xbff7f218e25a7461,

    0xbff37efd8d87607e,

    0xbff0000000000000,

    0xbfea43002ae42850,

    0xbfe561b82ab7f990,

    0xbfe11ab7190834ec,

    0xbfda827999fcef32,

    0xbfd36a08355c63dc,

    0xbfc975f5e0553158,

    0xbfb936bb8c5b2da2,

];

pub(crate) struct TanfEval {

    pub(crate) tan_k: f64,

    pub(crate) tan_y: f64,

}

#[inline]

pub(crate) fn tanpif_eval(y: f64, k: i64) -> TanfEval {

    let y_sqr = y * y;

    // After range reduction, k = round(x * 32 / pi) and y = (x * 32 / pi) - k.

    // So k is an integer and -0.5 <= y <= 0.5.

    // picking minus sin and cos according to quadrant

    let tan_k = f64::from_bits(TAN_K_PI_OVER32[((k as u64) & 63) as usize]);

    // tan(x*pi/32) generated by Sollya:

    // d = [0, 0.5];

    // f_tan = tan(y*pi/32)/y;

    // Q = fpminimax(f_tan, [|0, 2, 4, 6|], [|D...|], d, relative, floating);

    // See ./notes/tanpif.sollya

    let tan_y = f_polyeval4(

        y_sqr,

        f64::from_bits(0x3fb921fb54442cef),

        f64::from_bits(0x3f34abbce63a363e),

        f64::from_bits(0x3eb466baced705e8),

        f64::from_bits(0x3e346a33cde88184),

    ) * y;

    TanfEval { tan_y, tan_k }

}

#[inline]

pub(crate) fn tanf_eval(x: f64, x_abs: u32) -> TanfEval {

    let (y, k) = ArgumentReducer { x, x_abs }.reduce();

    let y_sqr = y * y;

    // After range reduction, k = round(x * 32 / pi) and y = (x * 32 / pi) - k.

    // So k is an integer and -0.5 <= y <= 0.5.

    // picking minus sin and cos according to quadrant

    let tan_k = f64::from_bits(TAN_K_PI_OVER32[(k & 63) as usize]);

    // tan(x*pi/32) generated by Sollya:

    // d = [0, 0.5];

    // f_tan = tan(x*pi/32)/x;

    // Q = fpminimax(f_tan, [|0, 2, 4, 6|], [|D...|], d);

    // See ./notes/tanf.sollya

    let tan_y = f_polyeval4(

        y_sqr,

        f64::from_bits(0x3fb921fb54442cef),

        f64::from_bits(0x3f34abbce63a363e),

        f64::from_bits(0x3eb466baced705e8),

        f64::from_bits(0x3e346a33cde88184),

    ) * y;

    TanfEval { tan_y, tan_k }

}