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#include "precomp.hpp"

using namespace cv;
using namespace cv::gpu;
using namespace std;

#if !defined (HAVE_CUDA)

cv::gpu::StereoBeliefPropagation_GPU::StereoBeliefPropagation_GPU(int, int, int, int, float) { throw_nogpu(); }
cv::gpu::StereoBeliefPropagation_GPU::StereoBeliefPropagation_GPU(int, int, int, float, float, float, float, int, float) { throw_nogpu(); }

void cv::gpu::StereoBeliefPropagation_GPU::operator()(const GpuMat&, const GpuMat&, GpuMat&) { throw_nogpu(); }
void cv::gpu::StereoBeliefPropagation_GPU::operator()(const GpuMat&, const GpuMat&, GpuMat&, const Stream&) { throw_nogpu(); }

bool cv::gpu::StereoBeliefPropagation_GPU::checkIfGpuCallReasonable() { throw_nogpu(); return false; }

#else /* !defined (HAVE_CUDA) */

const float DEFAULT_MAX_DATA_TERM = 10.0f;
const float DEFAULT_DATA_WEIGHT = 0.07f;
const float DEFAULT_MAX_DISC_TERM = 1.7f;
const float DEFAULT_DISC_SINGLE_JUMP = 1.0f;

namespace cv { namespace gpu { namespace impl {
    void load_constants(int ndisp, float max_data_term, float data_weight, float max_disc_term, float disc_single_jump);
    void comp_data(int msg_type, const DevMem2D& l, const DevMem2D& r, int channels, DevMem2D mdata, const cudaStream_t& stream);
    void data_step_down(int dst_cols, int dst_rows, int src_rows, int msg_type, const DevMem2D& src, DevMem2D dst, const cudaStream_t& stream);
    void level_up_messages(int dst_idx, int dst_cols, int dst_rows, int src_rows, int msg_type, DevMem2D* mus, DevMem2D* mds, DevMem2D* mls, DevMem2D* mrs, const cudaStream_t& stream);
    void calc_all_iterations(int cols, int rows, int iters, int msg_type, DevMem2D& u, DevMem2D& d, DevMem2D& l, DevMem2D& r, const DevMem2D& data, const cudaStream_t& stream);
    void output(int msg_type, const DevMem2D& u, const DevMem2D& d, const DevMem2D& l, const DevMem2D& r, const DevMem2D& data, DevMem2D disp, const cudaStream_t& stream);
}}}

cv::gpu::StereoBeliefPropagation_GPU::StereoBeliefPropagation_GPU(int ndisp_, int iters_, int levels_, int msg_type_, float msg_scale_)
    : ndisp(ndisp_), iters(iters_), levels(levels_), 
      max_data_term(DEFAULT_MAX_DATA_TERM), data_weight(DEFAULT_DATA_WEIGHT), 
      max_disc_term(DEFAULT_MAX_DISC_TERM), disc_single_jump(DEFAULT_DISC_SINGLE_JUMP), 
      msg_type(msg_type_), msg_scale(msg_scale_), datas(levels_)
{
    CV_Assert(0 < ndisp && 0 < iters && 0 < levels);
}

cv::gpu::StereoBeliefPropagation_GPU::StereoBeliefPropagation_GPU(int ndisp_, int iters_, int levels_, float max_data_term_, float data_weight_, float max_disc_term_, float disc_single_jump_, int msg_type_, float msg_scale_)
    : ndisp(ndisp_), iters(iters_), levels(levels_), 
      max_data_term(max_data_term_), data_weight(data_weight_), 
      max_disc_term(max_disc_term_), disc_single_jump(disc_single_jump_), 
      msg_type(msg_type_), msg_scale(msg_scale_), datas(levels_)
{
    CV_Assert(0 < ndisp && 0 < iters && 0 < levels);
}

static bool checkMsgOverflow(int levels, float max_data_term, float data_weight, float max_disc_term, float msg_scale)
{
    float maxV = ceil(max_disc_term * msg_scale);
    float maxD = ceil(max_data_term * data_weight * msg_scale);

    float maxMsg = maxV + (maxD * pow(4.0f, (float)levels));
    maxMsg = maxV + (maxD * pow(4.0f, (float)levels)) + 3 * maxMsg;

    return (maxMsg > numeric_limits<short>::max());
}

static void stereo_bp_gpu_operator(int ndisp, int iters, int levels, 
                                   float max_data_term, float data_weight, float max_disc_term, float disc_single_jump,
                                   int msg_type, float& msg_scale,
                                   GpuMat& u, GpuMat& d, GpuMat& l, GpuMat& r,
                                   GpuMat& u2, GpuMat& d2, GpuMat& l2, GpuMat& r2,
                                   vector<GpuMat>& datas, GpuMat& out,
                                   const GpuMat& left, const GpuMat& right, GpuMat& disp,
                                   const cudaStream_t& stream)
{
    CV_DbgAssert(left.cols == right.cols && left.rows == right.rows && left.type() == right.type() && left.type() == CV_8U);

    const Scalar zero = Scalar::all(0);

    int rows = left.rows;
    int cols = left.cols;

    int divisor = (int)pow(2.f, levels - 1.0f);
    int lowest_cols = cols / divisor;
    int lowest_rows = rows / divisor;
    const int min_image_dim_size = 2;
    CV_Assert(min(lowest_cols, lowest_rows) > min_image_dim_size);

    switch (msg_type)
    {
    case StereoBeliefPropagation_GPU::MSG_TYPE_AUTO:
        if (!checkMsgOverflow(levels, max_data_term, data_weight, max_disc_term, 100.0f))
        {
            msg_type = CV_16S;
            msg_scale = 100.0f;
        }
        else if (!checkMsgOverflow(levels, max_data_term, data_weight, max_disc_term, 64.0f))
        {
            msg_type = CV_16S;
            msg_scale = 64.0f;
        }
        else if (!checkMsgOverflow(levels, max_data_term, data_weight, max_disc_term, 32.0f))
        {
            msg_type = CV_16S;
            msg_scale = 32.0f;
        }
        else if (!checkMsgOverflow(levels, max_data_term, data_weight, max_disc_term, 16.0f))
        {
            msg_type = CV_16S;
            msg_scale = 16.0f;
        }
        else if (!checkMsgOverflow(levels, max_data_term, data_weight, max_disc_term, 10.0f))
        {
            msg_type = CV_16S;
            msg_scale = 10.0f;
        }
        else
        {
            msg_type = CV_32F;
            msg_scale = 1.0f;
        }
        break;
    case StereoBeliefPropagation_GPU::MSG_TYPE_FLOAT:
        msg_type = CV_32F;
        msg_scale = 1.0f;
        break;
    case StereoBeliefPropagation_GPU::MSG_TYPE_SHORT_SCALE_AUTO:
        msg_type = CV_16S;
        if (!checkMsgOverflow(levels, max_data_term, data_weight, max_disc_term, 100.0f))
            msg_scale = 100.0f;
        else if (!checkMsgOverflow(levels, max_data_term, data_weight, max_disc_term, 64.0f))
            msg_scale = 64.0f;
        else if (!checkMsgOverflow(levels, max_data_term, data_weight, max_disc_term, 32.0f))
            msg_scale = 32.0f;
        else if (!checkMsgOverflow(levels, max_data_term, data_weight, max_disc_term, 16.0f))
            msg_scale = 16.0f;
        else
            msg_scale = 10.0f;
        break;
    case StereoBeliefPropagation_GPU::MSG_TYPE_SHORT_SCALE_MANUAL:
        msg_type = CV_16S;
        break;
    default:
        cv::gpu::error("Unsupported message type", __FILE__, __LINE__);
    }

    u.create(rows * ndisp, cols, msg_type);
    d.create(rows * ndisp, cols, msg_type);
    l.create(rows * ndisp, cols, msg_type);
    r.create(rows * ndisp, cols, msg_type);

    if (levels & 1)
    {
        //can clear less area
        u = zero;
        d = zero;
        l = zero;
        r = zero;
    }

    if (levels > 1)
    {
        int less_rows = (rows + 1) / 2;
        int less_cols = (cols + 1) / 2;

        u2.create(less_rows * ndisp, less_cols, msg_type);
        d2.create(less_rows * ndisp, less_cols, msg_type);
        l2.create(less_rows * ndisp, less_cols, msg_type);
        r2.create(less_rows * ndisp, less_cols, msg_type);

        if ((levels & 1) == 0)
        {
            u2 = zero;
            d2 = zero;
            l2 = zero;
            r2 = zero;
        }
    }

    impl::load_constants(ndisp, max_data_term, msg_scale * data_weight, msg_scale * max_disc_term, msg_scale * disc_single_jump);

    datas.resize(levels);

    AutoBuffer<int> buf(levels << 1);

    int* cols_all = buf;
    int* rows_all = cols_all + levels;

    cols_all[0] = cols;
    rows_all[0] = rows;

    datas[0].create(rows * ndisp, cols, msg_type);

    impl::comp_data(msg_type, left, right, left.channels(), datas.front(), stream);

    for (int i = 1; i < levels; i++)
    {
        cols_all[i] = (cols_all[i-1] + 1) / 2;
        rows_all[i] = (rows_all[i-1] + 1) / 2;

        datas[i].create(rows_all[i] * ndisp, cols_all[i], msg_type);

        impl::data_step_down(cols_all[i], rows_all[i], rows_all[i-1], msg_type, datas[i-1], datas[i], stream);
    }

    DevMem2D mus[] = {u, u2};
    DevMem2D mds[] = {d, d2};
    DevMem2D mrs[] = {r, r2};
    DevMem2D mls[] = {l, l2};

    int mem_idx = (levels & 1) ? 0 : 1;

    for (int i = levels - 1; i >= 0; i--)
    {
        // for lower level we have already computed messages by setting to zero
        if (i != levels - 1)
            impl::level_up_messages(mem_idx, cols_all[i], rows_all[i], rows_all[i+1], msg_type, mus, mds, mls, mrs, stream);

        impl::calc_all_iterations(cols_all[i], rows_all[i], iters, msg_type, mus[mem_idx], mds[mem_idx], mls[mem_idx], mrs[mem_idx], datas[i], stream);

        mem_idx = (mem_idx + 1) & 1;
    }

    if (disp.empty())
        disp.create(rows, cols, CV_16S);

    if (disp.type() == CV_16S)
    {
        disp = zero;
        impl::output(msg_type, u, d, l, r, datas.front(), disp, stream);
    }
    else
    {
        out.create(rows, cols, CV_16S);
        out = zero;

        impl::output(msg_type, u, d, l, r, datas.front(), out, stream);

        out.convertTo(disp, disp.type());
    }
}

void cv::gpu::StereoBeliefPropagation_GPU::operator()(const GpuMat& left, const GpuMat& right, GpuMat& disp)
{
    ::stereo_bp_gpu_operator(ndisp, iters, levels, max_data_term, data_weight, max_disc_term, disc_single_jump, msg_type, msg_scale, u, d, l, r, u2, d2, l2, r2, datas, out, left, right, disp, 0);
}

void cv::gpu::StereoBeliefPropagation_GPU::operator()(const GpuMat& left, const GpuMat& right, GpuMat& disp, const Stream& stream)
{
    ::stereo_bp_gpu_operator(ndisp, iters, levels, max_data_term, data_weight, max_disc_term, disc_single_jump, msg_type, msg_scale, u, d, l, r, u2, d2, l2, r2, datas, out, left, right, disp, StreamAccessor::getStream(stream));
}

bool cv::gpu::StereoBeliefPropagation_GPU::checkIfGpuCallReasonable()
{
    if (0 == getCudaEnabledDeviceCount())
        return false;

    int device = getDevice();

    int minor, major;
    getComputeCapability(device, &major, &minor);
    int numSM = getNumberOfSMs(device);

    if (major > 1 || numSM > 16)
        return true;

    return false;
}

#endif /* !defined (HAVE_CUDA) */