pxdct 0.2.2

/*
 * // Copyright (c) Radzivon Bartoshyk 1/2026. 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::avx::stored::AvxStoreD;
use crate::avx::util::fma;
use crate::dct2::{MixedRadix5Sample, radixq_cos_twiddle, radixq_rotation_twiddle};
use crate::util::{DctSample, try_vec};
use crate::{PxdctError, PxdctExecutor};
use num_traits::{AsPrimitive, One};
use std::sync::Arc;

/// Radix-5 DCT-II implementation using direct decomposition algorithm.
///
/// This implements a fast DCT-II for lengths divisible by 5, decomposing the transform
/// into smaller sub-transforms around a center pivot element. The algorithm exploits
/// the symmetry structure: C₀ - S₁ - A - S₃ - C₄, where A is the center buffer.
pub(crate) struct AvxDct2MixedRadix5d {
    /// Precomputed rotation twiddles: tan(π(q-1-2m)k/(2N)) for combining C and S buffers
    rotation_layer: Vec<AvxStoreD>,
    /// Precomputed cosine twiddles for even and odd components
    cos_twiddles: Vec<AvxStoreD>,
    inner_dct: Arc<dyn PxdctExecutor<f64> + Send + Sync>,
    execution_length: usize,
}

#[target_feature(enable = "avx2")]
pub(crate) fn dct2_radix5_rotation_twiddles_avxd(
    main_q: usize,
    q_modules: usize,
    len: usize,
) -> Vec<AvxStoreD> {
    let simd_groups = q_modules.div_ceil(4);
    let inner_groups = (main_q.saturating_sub(3)) / 2 + 1;

    // We need 2 complex values per k (rotation_re and rotation_im)
    // Each complex has re and im, so 4 values per k
    // Times inner_groups for each m
    let mut twiddles = Vec::with_capacity(simd_groups * 4 * inner_groups);

    let working_modules = q_modules - 1;

    let mut uk = 0usize;
    while uk + 4 <= working_modules {
        let k = uk + 1;

        let layer0 = radixq_rotation_twiddle(5, 0, k.as_(), (q_modules - k).as_(), len);
        let layer1 = radixq_rotation_twiddle(5, 0, (k + 1).as_(), (q_modules - (k + 1)).as_(), len);
        let layer2 = radixq_rotation_twiddle(5, 0, (k + 2).as_(), (q_modules - (k + 2)).as_(), len);
        let layer3 = radixq_rotation_twiddle(5, 0, (k + 3).as_(), (q_modules - (k + 3)).as_(), len);

        twiddles.push(AvxStoreD::set_values(
            layer0.re, layer1.re, layer2.re, layer3.re,
        ));
        twiddles.push(AvxStoreD::set_values(
            layer0.im, layer1.im, layer2.im, layer3.im,
        ));

        let layer0 = radixq_rotation_twiddle(5, 1, k.as_(), (q_modules - k).as_(), len);
        let layer1 = radixq_rotation_twiddle(5, 1, (k + 1).as_(), (q_modules - (k + 1)).as_(), len);
        let layer2 = radixq_rotation_twiddle(5, 1, (k + 2).as_(), (q_modules - (k + 2)).as_(), len);
        let layer3 = radixq_rotation_twiddle(5, 1, (k + 3).as_(), (q_modules - (k + 3)).as_(), len);

        twiddles.push(AvxStoreD::set_values(
            layer0.re, layer1.re, layer2.re, layer3.re,
        ));
        twiddles.push(AvxStoreD::set_values(
            layer0.im, layer1.im, layer2.im, layer3.im,
        ));
        uk += 4;
    }

    let remainder = working_modules - (working_modules / 4) * 4;
    if remainder > 0 {
        let k = uk + 1;

        let mut array_re = [0.; 4];
        let mut array_im = [0.; 4];
        for i in 0..remainder {
            let layer =
                radixq_rotation_twiddle(5, 0, (k + i).as_(), (q_modules - (k + i)).as_(), len);
            array_re[i] = layer.re;
            array_im[i] = layer.im;
        }

        twiddles.push(AvxStoreD::load(array_re.as_ref()));
        twiddles.push(AvxStoreD::load(array_im.as_ref()));

        for i in 0..remainder {
            let layer =
                radixq_rotation_twiddle(5, 1, (k + i).as_(), (q_modules - (k + i)).as_(), len);
            array_re[i] = layer.re;
            array_im[i] = layer.im;
        }

        twiddles.push(AvxStoreD::load(array_re.as_ref()));
        twiddles.push(AvxStoreD::load(array_im.as_ref()));
    }

    twiddles
}

#[target_feature(enable = "avx2")]
pub(crate) fn dct2_radix5_cos_twiddles_avxd(
    main_q: usize,
    q_modules: usize,
    len: usize,
) -> Vec<AvxStoreD> {
    let simd_groups = q_modules.div_ceil(4);
    let inner_groups = (main_q.saturating_sub(3)) / 2 + 1;

    // We need 2 complex values per k (rotation_re and rotation_im)
    // Each complex has re and im, so 4 values per k
    // Times inner_groups for each m
    let mut twiddles = Vec::with_capacity(simd_groups * 4 * inner_groups);

    let working_modules = q_modules - 1;

    let mut uk = 0usize;
    while uk + 4 <= working_modules {
        let k = uk + 1;

        let mut array_re = [0.; 4];
        let mut array_im = [0.; 4];
        for i in 0..4 {
            array_re[i] = radixq_cos_twiddle(5, 0, (k + i).as_(), len);
            array_im[i] = radixq_cos_twiddle(5, 0, (q_modules - (k + i)).as_(), len);
        }

        twiddles.push(AvxStoreD::load(array_re.as_ref()));
        twiddles.push(AvxStoreD::load(array_im.as_ref()));

        for i in 0..4 {
            array_re[i] = radixq_cos_twiddle(5, 1, (k + i).as_(), len);
            array_im[i] = radixq_cos_twiddle(5, 1, (q_modules - (k + i)).as_(), len);
        }

        twiddles.push(AvxStoreD::load(array_re.as_ref()));
        twiddles.push(AvxStoreD::load(array_im.as_ref()));
        uk += 4;
    }

    let remainder = working_modules - (working_modules / 4) * 4;
    if remainder > 0 {
        let k = uk + 1;

        let mut array_re = [0.; 4];
        let mut array_im = [0.; 4];
        for i in 0..remainder {
            array_re[i] = radixq_cos_twiddle(5, 0, (k + i).as_(), len);
            array_im[i] = radixq_cos_twiddle(5, 0, (q_modules - (k + i)).as_(), len);
        }

        twiddles.push(AvxStoreD::load(array_re.as_ref()));
        twiddles.push(AvxStoreD::load(array_im.as_ref()));

        for i in 0..remainder {
            array_re[i] = radixq_cos_twiddle(5, 1, (k + i).as_(), len);
            array_im[i] = radixq_cos_twiddle(5, 1, (q_modules - (k + i)).as_(), len);
        }

        twiddles.push(AvxStoreD::load(array_re.as_ref()));
        twiddles.push(AvxStoreD::load(array_im.as_ref()));
    }

    twiddles
}

impl AvxDct2MixedRadix5d {
    pub(crate) fn new(
        len: usize,
        inner_dct: Arc<dyn PxdctExecutor<f64> + Send + Sync>,
    ) -> Result<AvxDct2MixedRadix5d, PxdctError> {
        assert!(
            len.is_multiple_of(5),
            "Mixed radix 5 should not be called on sizes no divisible by 5"
        );

        let q_modules = len / 5;

        // always 2 inner groups in Radix-5

        let rotation_layer = unsafe { dct2_radix5_rotation_twiddles_avxd(5, q_modules, len) };

        let cos_twiddles = unsafe { dct2_radix5_cos_twiddles_avxd(5, q_modules, len) };

        Ok(AvxDct2MixedRadix5d {
            rotation_layer,
            inner_dct,
            cos_twiddles,
            execution_length: len,
        })
    }
}

impl AvxDct2MixedRadix5d {
    #[target_feature(enable = "avx2", enable = "fma")]
    fn execute_impl(&self, data: &mut [f64]) -> Result<(), PxdctError> {
        if !data.len().is_multiple_of(self.execution_length) {
            return Err(PxdctError::InvalidSizeMultiplier(
                data.len(),
                self.execution_length,
            ));
        }

        assert!(!self.cos_twiddles.is_empty());

        let mut scratch = try_vec![f64::default(); self.execution_length];

        let q_modules = self.execution_length / 5;

        for chunk in data.chunks_exact_mut(self.execution_length) {
            let (a_buffer, c_s_buffer) = scratch.split_at_mut(q_modules);
            let (c_buffer, s_buffer) = c_s_buffer.split_at_mut(q_modules * 2);

            // Step 1: Decompose input into A (center), C (even-symmetric), S (odd-symmetric) buffers
            for (n, dst) in a_buffer.iter_mut().enumerate() {
                unsafe {
                    *dst = *chunk.get_unchecked(n * 5 + 2);
                }
            }

            // Extract and combine symmetric pairs with sign alternation for S buffer
            for (m, (c_buffer, s_buffer)) in c_buffer
                .chunks_exact_mut(q_modules)
                .zip(s_buffer.chunks_exact_mut(q_modules))
                .enumerate()
            {
                let mut sign = f64::one();
                for (n, (c_dst, s_dst)) in c_buffer.iter_mut().zip(s_buffer.iter_mut()).enumerate()
                {
                    let u0 = unsafe { *chunk.get_unchecked(5 * n + m) };
                    let u1 = unsafe { *chunk.get_unchecked(5 * n + 5 - m - 1) };

                    *c_dst = u0 + u1;
                    *s_dst = (u0 - u1).mulsign(sign);

                    sign = -sign;
                }
            }

            // Step 2: Apply DCT-II to all buffers (A, C₀, C₁, S₀, S₁)
            self.inner_dct.execute(&mut scratch)?;

            let (a_buffer, c_s_buffer) = scratch.split_at_mut(q_modules);
            let (c_buffer, s_buffer) = c_s_buffer.split_at_mut(q_modules * 2);

            {
                // Step 3: Recombine transformed buffers with twiddle factors

                // Handle k=0 case (DC and low frequencies)
                let qc = c_buffer[0];
                let mut c0 = qc;
                let mut c1 = qc * f64::R5_COS_EVEN2_M0;
                let mut c2 = qc * f64::R5_COS_EVEN4_M0;

                let s0_twiddled = s_buffer[0];

                // Odd components: S₁ uses j=1 (abs), S₃ uses j=3 (negated)
                let mut s0 = s0_twiddled * f64::R5_SIN_ODD_M0; // S₁: abs(sin(3π/5))
                let mut s1 = s0_twiddled * f64::R5_SIN_ODD1_M0; // S₃: -sin(π/5)

                {
                    let ci = unsafe { *c_buffer.get_unchecked(q_modules) };
                    let si = unsafe { *s_buffer.get_unchecked(q_modules) };

                    let twiddle_ci = ci;
                    let twiddle_si = si;

                    c0 += ci;
                    c1 = fma(twiddle_ci, f64::R5_COS_EVEN4_M0, c1);
                    c2 = fma(twiddle_ci, f64::R5_COS_EVEN2_M0, c2);
                    s0 = fma(twiddle_si, -f64::R5_SIN_ODD1_M0, s0);
                    s1 = fma(twiddle_si, f64::R5_SIN_ODD_M0, s1);
                }

                let a0 = a_buffer[0];
                let dc = c0 + a0;
                unsafe {
                    *chunk.get_unchecked_mut(0) = dc;
                }

                let dc2 = c2 + a0;
                unsafe {
                    *chunk.get_unchecked_mut(q_modules * 4) = dc2;
                }
                unsafe {
                    *chunk.get_unchecked_mut(q_modules * 3) = -s1;
                }

                unsafe {
                    *chunk.get_unchecked_mut(q_modules) = s0;
                }

                unsafe {
                    let idx1 = q_modules * 2;
                    let qid2 = -(c1 + a0); // negated 2j
                    *chunk.get_unchecked_mut(idx1) = qid2;
                }

                let mut k = 1usize;
                let mut uk = 0usize;

                while k + 4 <= q_modules {
                    let rotation_twiddle_re = unsafe { *self.rotation_layer.get_unchecked(uk) };
                    let rotation_twiddle_im = unsafe { *self.rotation_layer.get_unchecked(uk + 1) };

                    let c_forward = AvxStoreD::load(unsafe { c_buffer.get_unchecked(k..) });
                    let s_forward =
                        AvxStoreD::load(unsafe { s_buffer.get_unchecked(q_modules - k - 3..) })
                            .reverse();

                    let rotated_dc = fma(s_forward, rotation_twiddle_re, c_forward);

                    let twiddle_re = unsafe { *self.cos_twiddles.get_unchecked(uk) };
                    let twiddle_im = unsafe { *self.cos_twiddles.get_unchecked(uk + 1) };

                    let twiddled_dc = rotated_dc * twiddle_re;

                    let mut dc0 = twiddled_dc;
                    let mut dc2 = twiddled_dc * f64::R5_COS_EVEN2_M0;
                    let mut dc4 = twiddled_dc * f64::R5_COS_EVEN4_M0;

                    let rotated_ds = fma(c_forward, rotation_twiddle_im, s_forward);

                    let twiddled_ds = rotated_ds * twiddle_im;

                    let mut ds1 = twiddled_ds * f64::R5_SIN_ODD_M0;
                    let mut ds3 = twiddled_ds * f64::R5_SIN_ODD1_M0;

                    {
                        let c_forward =
                            AvxStoreD::load(unsafe { c_buffer.get_unchecked(q_modules + k..) });
                        let s_forward = AvxStoreD::load(unsafe {
                            s_buffer.get_unchecked(q_modules * 2 - k - 3..)
                        })
                        .reverse();

                        let rotation_twiddle_re =
                            unsafe { *self.rotation_layer.get_unchecked(uk + 2) };
                        let rotation_twiddle_im =
                            unsafe { *self.rotation_layer.get_unchecked(uk + 3) };

                        let twiddle_re = unsafe { *self.cos_twiddles.get_unchecked(uk + 2) };
                        let twiddle_im = unsafe { *self.cos_twiddles.get_unchecked(uk + 3) };

                        let rotated_dc1 = fma(s_forward, rotation_twiddle_re, c_forward);
                        let rotated_ds2 = fma(c_forward, rotation_twiddle_im, s_forward);

                        let twiddled_dc = twiddle_re * rotated_dc1;
                        let twiddled_ds = twiddle_im * rotated_ds2;

                        dc0 = twiddled_dc + dc0;
                        dc2 = AvxStoreD::f64_mul_add(f64::R5_COS_EVEN4_M0, twiddled_dc, dc2);
                        dc4 = AvxStoreD::f64_mul_add(f64::R5_COS_EVEN2_M0, twiddled_dc, dc4);

                        ds1 = AvxStoreD::f64_mul_nadd(f64::R5_SIN_ODD1_M0, twiddled_ds, ds1);
                        ds3 = AvxStoreD::f64_mul_add(f64::R5_SIN_ODD_M0, twiddled_ds, ds3);
                    }

                    let a0 = AvxStoreD::load(unsafe { a_buffer.get_unchecked(k..) });
                    let dc = dc0 + a0;
                    unsafe {
                        dc.write(chunk.get_unchecked_mut(k..));
                    }

                    let dss1 = AvxStoreD::f64_mul_add(2., ds1, -dc);
                    unsafe {
                        let idx = q_modules * 2 - k - 3;
                        dss1.reverse().write(chunk.get_unchecked_mut(idx..));
                    }

                    dc2 = -(dc2 + a0); // negated 2j
                    dc2 = AvxStoreD::f64_mul_add(2., dc2, -dss1);
                    unsafe {
                        let idx1 = q_modules * 2 + k;
                        dc2.write(chunk.get_unchecked_mut(idx1..));
                    }

                    let dss3 = AvxStoreD::f64_mul_add(2., -ds3, -dc2);
                    unsafe {
                        let idx = q_modules * 4 - k - 3;
                        dss3.reverse().write(chunk.get_unchecked_mut(idx..));
                    }

                    dc4 += a0;

                    let idx1 = q_modules * 4 + k;
                    unsafe {
                        let uq = AvxStoreD::f64_mul_add(2., dc4, -dss3);
                        uq.write(chunk.get_unchecked_mut(idx1..));
                    }
                    k += 4;
                    uk += 4;
                }

                let remainder = q_modules - k;
                if remainder == 3 {
                    let rotation_twiddle_re = unsafe { *self.rotation_layer.get_unchecked(uk) };
                    let rotation_twiddle_im = unsafe { *self.rotation_layer.get_unchecked(uk + 1) };

                    let c_forward = AvxStoreD::load3(unsafe { c_buffer.get_unchecked(k..) });
                    let s_forward =
                        AvxStoreD::load3(unsafe { s_buffer.get_unchecked(q_modules - k - 2..) })
                            .reverse3();

                    let rotated_dc = fma(s_forward, rotation_twiddle_re, c_forward);

                    let twiddle_re = unsafe { *self.cos_twiddles.get_unchecked(uk) };
                    let twiddle_im = unsafe { *self.cos_twiddles.get_unchecked(uk + 1) };

                    let twiddled_dc = rotated_dc * twiddle_re;

                    let mut dc0 = twiddled_dc;
                    let mut dc2 = twiddled_dc * f64::R5_COS_EVEN2_M0;
                    let mut dc4 = twiddled_dc * f64::R5_COS_EVEN4_M0;

                    let rotated_ds = fma(c_forward, rotation_twiddle_im, s_forward);

                    let twiddled_ds = rotated_ds * twiddle_im;

                    let mut ds1 = twiddled_ds * f64::R5_SIN_ODD_M0;
                    let mut ds3 = twiddled_ds * f64::R5_SIN_ODD1_M0;

                    {
                        let c_forward =
                            AvxStoreD::load3(unsafe { c_buffer.get_unchecked(q_modules + k..) });
                        let s_forward = AvxStoreD::load3(unsafe {
                            s_buffer.get_unchecked(q_modules * 2 - k - 2..)
                        })
                        .reverse3();

                        let rotation_twiddle_re =
                            unsafe { *self.rotation_layer.get_unchecked(uk + 2) };
                        let rotation_twiddle_im =
                            unsafe { *self.rotation_layer.get_unchecked(uk + 3) };

                        let twiddle_re = unsafe { *self.cos_twiddles.get_unchecked(uk + 2) };
                        let twiddle_im = unsafe { *self.cos_twiddles.get_unchecked(uk + 3) };

                        let rotated_dc1 = fma(s_forward, rotation_twiddle_re, c_forward);
                        let rotated_ds2 = fma(c_forward, rotation_twiddle_im, s_forward);

                        let twiddled_dc = twiddle_re * rotated_dc1;
                        let twiddled_ds = twiddle_im * rotated_ds2;

                        dc0 = twiddled_dc + dc0;
                        dc2 = AvxStoreD::f64_mul_add(f64::R5_COS_EVEN4_M0, twiddled_dc, dc2);
                        dc4 = AvxStoreD::f64_mul_add(f64::R5_COS_EVEN2_M0, twiddled_dc, dc4);

                        ds1 = AvxStoreD::f64_mul_nadd(f64::R5_SIN_ODD1_M0, twiddled_ds, ds1);
                        ds3 = AvxStoreD::f64_mul_add(f64::R5_SIN_ODD_M0, twiddled_ds, ds3);
                    }

                    let a0 = AvxStoreD::load3(unsafe { a_buffer.get_unchecked(k..) });
                    let dc = dc0 + a0;
                    unsafe {
                        dc.write3(chunk.get_unchecked_mut(k..));
                    }

                    let dss1 = AvxStoreD::f64_mul_add(2., ds1, -dc);
                    unsafe {
                        let idx = q_modules * 2 - k - 2;
                        dss1.reverse3().write3(chunk.get_unchecked_mut(idx..));
                    }

                    dc2 = -(dc2 + a0); // negated 2j
                    dc2 = AvxStoreD::f64_mul_add(2., dc2, -dss1);
                    unsafe {
                        let idx1 = q_modules * 2 + k;
                        dc2.write3(chunk.get_unchecked_mut(idx1..));
                    }

                    let dss3 = AvxStoreD::f64_mul_add(2., -ds3, -dc2);
                    unsafe {
                        let idx = q_modules * 4 - k - 2;
                        dss3.reverse3().write3(chunk.get_unchecked_mut(idx..));
                    }

                    dc4 += a0;

                    let idx1 = q_modules * 4 + k;
                    unsafe {
                        let uq = AvxStoreD::f64_mul_add(2., dc4, -dss3);
                        uq.write3(chunk.get_unchecked_mut(idx1..));
                    }
                } else if remainder == 2 {
                    let rotation_twiddle_re = unsafe { *self.rotation_layer.get_unchecked(uk) };
                    let rotation_twiddle_im = unsafe { *self.rotation_layer.get_unchecked(uk + 1) };

                    let c_forward = AvxStoreD::load2(unsafe { c_buffer.get_unchecked(k..) });
                    let s_forward =
                        AvxStoreD::load2(unsafe { s_buffer.get_unchecked(q_modules - k - 1..) })
                            .reverse2();

                    let rotated_dc = fma(s_forward, rotation_twiddle_re, c_forward);

                    let twiddle_re = unsafe { *self.cos_twiddles.get_unchecked(uk) };
                    let twiddle_im = unsafe { *self.cos_twiddles.get_unchecked(uk + 1) };

                    let twiddled_dc = rotated_dc * twiddle_re;

                    let mut dc0 = twiddled_dc;
                    let mut dc2 = twiddled_dc * f64::R5_COS_EVEN2_M0;
                    let mut dc4 = twiddled_dc * f64::R5_COS_EVEN4_M0;

                    let rotated_ds = fma(c_forward, rotation_twiddle_im, s_forward);

                    let twiddled_ds = rotated_ds * twiddle_im;

                    let mut ds1 = twiddled_ds * f64::R5_SIN_ODD_M0;
                    let mut ds3 = twiddled_ds * f64::R5_SIN_ODD1_M0;

                    {
                        let c_forward =
                            AvxStoreD::load2(unsafe { c_buffer.get_unchecked(q_modules + k..) });
                        let s_forward = AvxStoreD::load2(unsafe {
                            s_buffer.get_unchecked(q_modules * 2 - k - 1..)
                        })
                        .reverse2();

                        let rotation_twiddle_re =
                            unsafe { *self.rotation_layer.get_unchecked(uk + 2) };
                        let rotation_twiddle_im =
                            unsafe { *self.rotation_layer.get_unchecked(uk + 3) };

                        let twiddle_re = unsafe { *self.cos_twiddles.get_unchecked(uk + 2) };
                        let twiddle_im = unsafe { *self.cos_twiddles.get_unchecked(uk + 3) };

                        let rotated_dc1 = fma(s_forward, rotation_twiddle_re, c_forward);
                        let rotated_ds2 = fma(c_forward, rotation_twiddle_im, s_forward);

                        let twiddled_dc = twiddle_re * rotated_dc1;
                        let twiddled_ds = twiddle_im * rotated_ds2;

                        dc0 = twiddled_dc + dc0;
                        dc2 = AvxStoreD::f64_mul_add(f64::R5_COS_EVEN4_M0, twiddled_dc, dc2);
                        dc4 = AvxStoreD::f64_mul_add(f64::R5_COS_EVEN2_M0, twiddled_dc, dc4);

                        ds1 = AvxStoreD::f64_mul_nadd(f64::R5_SIN_ODD1_M0, twiddled_ds, ds1);
                        ds3 = AvxStoreD::f64_mul_add(f64::R5_SIN_ODD_M0, twiddled_ds, ds3);
                    }

                    let a0 = AvxStoreD::load2(unsafe { a_buffer.get_unchecked(k..) });
                    let dc = dc0 + a0;
                    unsafe {
                        dc.write2(chunk.get_unchecked_mut(k..));
                    }

                    let dss1 = AvxStoreD::f64_mul_add(2., ds1, -dc);
                    unsafe {
                        let idx = q_modules * 2 - k - 1;
                        dss1.reverse2().write2(chunk.get_unchecked_mut(idx..));
                    }

                    dc2 = -(dc2 + a0); // negated 2j
                    dc2 = AvxStoreD::f64_mul_add(2., dc2, -dss1);
                    unsafe {
                        let idx1 = q_modules * 2 + k;
                        dc2.write2(chunk.get_unchecked_mut(idx1..));
                    }

                    let dss3 = AvxStoreD::f64_mul_add(2., -ds3, -dc2);
                    unsafe {
                        let idx = q_modules * 4 - k - 1;
                        dss3.reverse2().write2(chunk.get_unchecked_mut(idx..));
                    }

                    dc4 += a0;

                    let idx1 = q_modules * 4 + k;
                    unsafe {
                        let uq = AvxStoreD::f64_mul_add(2., dc4, -dss3);
                        uq.write2(chunk.get_unchecked_mut(idx1..));
                    }
                } else if remainder == 1 {
                    let rotation_twiddle_re = unsafe { *self.rotation_layer.get_unchecked(uk) };
                    let rotation_twiddle_im = unsafe { *self.rotation_layer.get_unchecked(uk + 1) };

                    let c_forward = AvxStoreD::load1(unsafe { c_buffer.get_unchecked(k..) });
                    let s_forward =
                        AvxStoreD::load1(unsafe { s_buffer.get_unchecked(q_modules - k..) });

                    let rotated_dc = fma(s_forward, rotation_twiddle_re, c_forward);

                    let twiddle_re = unsafe { *self.cos_twiddles.get_unchecked(uk) };
                    let twiddle_im = unsafe { *self.cos_twiddles.get_unchecked(uk + 1) };

                    let twiddled_dc = rotated_dc * twiddle_re;

                    let mut dc0 = twiddled_dc;
                    let mut dc2 = twiddled_dc * f64::R5_COS_EVEN2_M0;
                    let mut dc4 = twiddled_dc * f64::R5_COS_EVEN4_M0;

                    let rotated_ds = fma(c_forward, rotation_twiddle_im, s_forward);

                    let twiddled_ds = rotated_ds * twiddle_im;

                    let mut ds1 = twiddled_ds * f64::R5_SIN_ODD_M0;
                    let mut ds3 = twiddled_ds * f64::R5_SIN_ODD1_M0;

                    {
                        let c_forward =
                            AvxStoreD::load1(unsafe { c_buffer.get_unchecked(q_modules + k..) });
                        let s_forward = AvxStoreD::load1(unsafe {
                            s_buffer.get_unchecked(q_modules * 2 - k..)
                        });

                        let rotation_twiddle_re =
                            unsafe { *self.rotation_layer.get_unchecked(uk + 2) };
                        let rotation_twiddle_im =
                            unsafe { *self.rotation_layer.get_unchecked(uk + 3) };

                        let twiddle_re = unsafe { *self.cos_twiddles.get_unchecked(uk + 2) };
                        let twiddle_im = unsafe { *self.cos_twiddles.get_unchecked(uk + 3) };

                        let rotated_dc1 = fma(s_forward, rotation_twiddle_re, c_forward);
                        let rotated_ds2 = fma(c_forward, rotation_twiddle_im, s_forward);

                        let twiddled_dc = twiddle_re * rotated_dc1;
                        let twiddled_ds = twiddle_im * rotated_ds2;

                        dc0 = twiddled_dc + dc0;
                        dc2 = AvxStoreD::f64_mul_add(f64::R5_COS_EVEN4_M0, twiddled_dc, dc2);
                        dc4 = AvxStoreD::f64_mul_add(f64::R5_COS_EVEN2_M0, twiddled_dc, dc4);

                        ds1 = AvxStoreD::f64_mul_nadd(f64::R5_SIN_ODD1_M0, twiddled_ds, ds1);
                        ds3 = AvxStoreD::f64_mul_add(f64::R5_SIN_ODD_M0, twiddled_ds, ds3);
                    }

                    let a0 = AvxStoreD::load1(unsafe { a_buffer.get_unchecked(k..) });
                    let dc = dc0 + a0;
                    unsafe {
                        dc.write1(chunk.get_unchecked_mut(k..));
                    }

                    let dss1 = AvxStoreD::f64_mul_add(2., ds1, -dc);
                    unsafe {
                        let idx = q_modules * 2 - k;
                        dss1.write1(chunk.get_unchecked_mut(idx..));
                    }

                    dc2 = -(dc2 + a0); // negated 2j
                    dc2 = AvxStoreD::f64_mul_add(2., dc2, -dss1);
                    unsafe {
                        let idx1 = q_modules * 2 + k;
                        dc2.write1(chunk.get_unchecked_mut(idx1..));
                    }

                    let dss3 = AvxStoreD::f64_mul_add(2., -ds3, -dc2);
                    unsafe {
                        let idx = q_modules * 4 - k;
                        dss3.write1(chunk.get_unchecked_mut(idx..));
                    }

                    dc4 += a0;

                    let idx1 = q_modules * 4 + k;
                    unsafe {
                        let uq = AvxStoreD::f64_mul_add(2., dc4, -dss3);
                        uq.write1(chunk.get_unchecked_mut(idx1..));
                    }
                }
            }
        }

        Ok(())
    }
}

impl PxdctExecutor<f64> for AvxDct2MixedRadix5d {
    fn execute(&self, data: &mut [f64]) -> Result<(), PxdctError> {
        unsafe { self.execute_impl(data) }
    }

    #[inline]
    fn length(&self) -> usize {
        self.execution_length
    }
}

#[cfg(test)]
mod tests {
    use super::*;
    use crate::Pxdct;
    use crate::tests::naive_dct2;

    #[test]
    fn test_radix5_dct() {
        let mut input = vec![0.; 45];
        for (i, z) in input.iter_mut().enumerate() {
            *z = i as f64 + rand::random::<f64>() * 10.0;
        }
        // let mut input = vec![
        //     7.6871257, 1.2637726, 11.096954, 4.113755, 6.3156953, 12.343984, 9.859292, 15.516256,
        //     12.010594, 18.957434, 11.183157, 16.510174, 13.310775, 21.062075, 19.775341, 20.445467,
        //     22.57258, 25.571342, 23.987795, 19.597996, 24.935028, 21.360756, 22.820232, 27.915956,
        //     31.28283, 24.935028, 21.360756, 22.820232, 27.915956, 31.28283,
        // ];
        let mut reference_input = input.clone();
        reference_input = naive_dct2(&reference_input);
        let bf =
            AvxDct2MixedRadix5d::new(input.len(), Pxdct::make_dct2_f64(input.len() / 5).unwrap())
                .unwrap();
        bf.execute(&mut input).unwrap();
        println!(
            "{:?}",
            input
                .iter()
                .enumerate()
                .map(|(i, x)| format!("({i}) {}", x))
                .collect::<Vec<_>>()
        );
        println!(
            "{:?}",
            reference_input
                .iter()
                .enumerate()
                .map(|(i, x)| format!("({i}) {}", x))
                .collect::<Vec<_>>()
        );
        input
            .iter()
            .zip(reference_input.iter())
            .enumerate()
            .for_each(|(i, (&src, &r0))| {
                if (src - r0).abs() > 1e-1 {
                    println!(
                        "Difference must be < {}, but it was {}, at position {i}",
                        1e-1,
                        (src - r0).abs()
                    )
                }
            });
    }
}