Function conv2d_dft

tests/validation/reference/DFT.cpp:398–430

template <typename T>
SimpleTensor<T> conv2d_dft(const SimpleTensor<T> &src, const SimpleTensor<T> &w, const PadStrideInfo &conv_info)
{
    // Pad input to full padding
    const PaddingList padding_in = {{0, w.shape()[0] - 1}, {0, w.shape()[1] - 1}};
    auto              padded_src = pad_layer(src, padding_in);

    // Flip weights
    std::vector<uint32_t> axis_v = {0, 1};
    SimpleTensor<int32_t> axis{TensorShape(2U), DataType::S32};
    std::copy(axis_v.begin(), axis_v.begin() + axis.shape().x(), axis.data());
    auto flipped_w = reverse(w, axis, /* use_inverted_axis */ false);

    // Pad weights to have the same size as input
    const PaddingList paddings_w = {{0, src.shape()[0] - 1}, {0, src.shape()[1] - 1}};
    auto              padded_w   = pad_layer(flipped_w, paddings_w);

    // Transform input and weights to frequency domain
    auto Fsrc = rdft_2d(padded_src);
    auto Fw   = rdft_2d(padded_w);

    // Perform dot product
    auto Fdst = complex_mul_and_reduce(Fsrc, Fw);

    // Transform output back to frequency domain
    auto conv_res = ridft_2d(Fdst);

    // Slice output
    const int start_left = w.shape().x() - conv_info.pad_left() - 1;
    const int start_top  = w.shape().y() - conv_info.pad_top() - 1;
    const int end_right  = conv_res.shape().x() - (w.shape().x() - conv_info.pad_right() - 1);
    const int end_botton = conv_res.shape().y() - (w.shape().y() - conv_info.pad_bottom() - 1);
    return slice(conv_res, Coordinates(start_left, start_top), Coordinates(end_right, end_botton));
}

// FP32
template SimpleTensor<float> rdft_1d(const SimpleTensor<float> &src);