Function build_tabs_linear_8u

dnn/src/naive/resize/resize_cv.cpp:265–305

linear 8u

// linear 8u
void build_tabs_linear_8u(
        const Mat8u& src, const Mat8u& dst, AlignedVector<int>& tabsx,
        AlignedVector<int>& tabsy, AlignedVector<int>& tabrx,
        AlignedVector<int>& tabry) {
    megdnn_assert(src.rows() >= 2);
    megdnn_assert(src.cols() >= 2);
    megdnn_assert(dst.rows() >= 2);
    megdnn_assert(dst.cols() >= 2);
    const float fx = static_cast<float>(dst.rows()) / src.rows();
    const float fy = static_cast<float>(dst.cols()) / src.cols();
    const float ifx = 1.0f / fx;
    const float ify = 1.0f / fy;
    for (size_t dx = 0; dx < dst.rows(); ++dx) {
        float rx = (dx + 0.5f) * ifx - 0.5f;
        int sx = static_cast<int>(floor(rx));
        rx -= sx;
        if (sx < 0) {
            sx = 0;
            rx = 0;
        } else if (sx + 1 >= static_cast<int>(src.rows())) {
            sx = src.rows() - 2;
            rx = 1;
        }
        tabsx[dx] = sx;
        tabrx[dx] = static_cast<int>(rx * (1 << SCALE));
    }
    for (size_t dy = 0; dy < dst.cols(); ++dy) {
        float ry = (dy + 0.5f) * ify - 0.5f;
        int sy = static_cast<int>(floor(ry));
        ry -= sy;
        if (sy < 0) {
            sy = 0;
            ry = 0;
        } else if (sy + 1 >= static_cast<int>(src.cols())) {
            sy = src.cols() - 2;
            ry = 1;
        }
        tabsy[dy] = sy;
        tabry[dy] = static_cast<int>(ry * (1 << SCALE));
    }
}

void resize_linear_8u(const Mat8u& src, Mat8u& dst) {
    AlignedVector<int> tabsx(dst.rows());