text: /*M///////////////////////////////////////////////////////////////////////////////////////
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  //                           License Agreement
  //                For Open Source Computer Vision Library
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  #include "precomp.hpp"
  #include BOSS_OPENCV_U_opencv2__core__hal__intrin_hpp //original-code:"opencv2/core/hal/intrin.hpp"
  
  #include <iostream>
  namespace cv
  {
  
  /* NOTE:
   *
   * Sobel-x: -1  0  1
   *          -2  0  2
   *          -1  0  1
   *
   * Sobel-y: -1 -2 -1
   *           0  0  0
   *           1  2  1
   */
  template <typename T>
  static inline void spatialGradientKernel( T& vx, T& vy,
                                            const T& v00, const T& v01, const T& v02,
                                            const T& v10,               const T& v12,
                                            const T& v20, const T& v21, const T& v22 )
  {
      // vx = (v22 - v00) + (v02 - v20) + 2 * (v12 - v10)
      // vy = (v22 - v00) + (v20 - v02) + 2 * (v21 - v01)
  
      T tmp_add = v22 - v00,
        tmp_sub = v02 - v20,
        tmp_x   = v12 - v10,
        tmp_y   = v21 - v01;
  
      vx = tmp_add + tmp_sub + tmp_x + tmp_x;
      vy = tmp_add - tmp_sub + tmp_y + tmp_y;
  }
  
  void spatialGradient( InputArray _src, OutputArray _dx, OutputArray _dy,
                        int ksize, int borderType )
  {
  
      // Prepare InputArray src
      Mat src = _src.getMat();
      CV_Assert( !src.empty() );
      CV_Assert( src.type() == CV_8UC1 );
      CV_Assert( borderType == BORDER_DEFAULT || borderType == BORDER_REPLICATE );
  
      // Prepare OutputArrays dx, dy
      _dx.create( src.size(), CV_16SC1 );
      _dy.create( src.size(), CV_16SC1 );
      Mat dx = _dx.getMat(),
          dy = _dy.getMat();
  
      // TODO: Allow for other kernel sizes
      CV_Assert(ksize == 3);
  
      // Get dimensions
      const int H = src.rows,
                W = src.cols;
  
      // Row, column indices
      int i = 0,
          j = 0;
  
      // Handle border types
      int i_top    = 0,     // Case for H == 1 && W == 1 && BORDER_REPLICATE
          i_bottom = H - 1,
          j_offl   = 0,     // j offset from 0th   pixel to reach -1st pixel
          j_offr   = 0;     // j offset from W-1th pixel to reach Wth  pixel
  
      if ( borderType == BORDER_DEFAULT ) // Equiv. to BORDER_REFLECT_101
      {
          if ( H > 1 )
          {
              i_top    = 1;
              i_bottom = H - 2;
          }
          if ( W > 1 )
          {
              j_offl = 1;
              j_offr = -1;
          }
      }
  
      // Pointer to row vectors
      uchar *p_src, *c_src, *n_src; // previous, current, next row
      short *c_dx,  *c_dy;
  
      int i_start = 0;
      int j_start = 0;
  #if CV_SIMD128 && CV_SSE2
      uchar *m_src;
      short *n_dx, *n_dy;
  
      // Characters in variable names have the following meanings:
      // u: unsigned char
      // s: signed int
      //
      // [row][column]
      // m: offset -1
      // n: offset  0
      // p: offset  1
      // Example: umn is offset -1 in row and offset 0 in column
      for ( i = 0; i < H - 1; i += 2 )
      {
          if   ( i == 0 ) p_src = src.ptr<uchar>(i_top);
          else            p_src = src.ptr<uchar>(i-1);
  
          c_src = src.ptr<uchar>(i);
          n_src = src.ptr<uchar>(i+1);
  
          if ( i == H - 2 ) m_src = src.ptr<uchar>(i_bottom);
          else              m_src = src.ptr<uchar>(i+2);
  
          c_dx = dx.ptr<short>(i);
          c_dy = dy.ptr<short>(i);
          n_dx = dx.ptr<short>(i+1);
          n_dy = dy.ptr<short>(i+1);
  
          v_uint8x16 v_select_m = v_uint8x16(0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
                                             0, 0, 0, 0xFF);
  
          // Process rest of columns 16-column chunks at a time
          for ( j = 1; j < W - 16; j += 16 )
          {
              // Load top row for 3x3 Sobel filter
              v_uint8x16 v_um = v_load(&p_src[j-1]);
              v_uint8x16 v_up = v_load(&p_src[j+1]);
              // TODO: Replace _mm_slli_si128 with hal method
              v_uint8x16 v_un = v_select(v_select_m, v_uint8x16(_mm_slli_si128(v_up.val, 1)),
                                                     v_uint8x16(_mm_srli_si128(v_um.val, 1)));
              v_uint16x8 v_um1, v_um2, v_un1, v_un2, v_up1, v_up2;
              v_expand(v_um, v_um1, v_um2);
              v_expand(v_un, v_un1, v_un2);
              v_expand(v_up, v_up1, v_up2);
              v_int16x8 v_s1m1 = v_reinterpret_as_s16(v_um1);
              v_int16x8 v_s1m2 = v_reinterpret_as_s16(v_um2);
              v_int16x8 v_s1n1 = v_reinterpret_as_s16(v_un1);
              v_int16x8 v_s1n2 = v_reinterpret_as_s16(v_un2);
              v_int16x8 v_s1p1 = v_reinterpret_as_s16(v_up1);
              v_int16x8 v_s1p2 = v_reinterpret_as_s16(v_up2);
  
              // Load second row for 3x3 Sobel filter
              v_um = v_load(&c_src[j-1]);
              v_up = v_load(&c_src[j+1]);
              // TODO: Replace _mm_slli_si128 with hal method
              v_un = v_select(v_select_m, v_uint8x16(_mm_slli_si128(v_up.val, 1)),
                                          v_uint8x16(_mm_srli_si128(v_um.val, 1)));
              v_expand(v_um, v_um1, v_um2);
              v_expand(v_un, v_un1, v_un2);
              v_expand(v_up, v_up1, v_up2);
              v_int16x8 v_s2m1 = v_reinterpret_as_s16(v_um1);
              v_int16x8 v_s2m2 = v_reinterpret_as_s16(v_um2);
              v_int16x8 v_s2n1 = v_reinterpret_as_s16(v_un1);
              v_int16x8 v_s2n2 = v_reinterpret_as_s16(v_un2);
              v_int16x8 v_s2p1 = v_reinterpret_as_s16(v_up1);
              v_int16x8 v_s2p2 = v_reinterpret_as_s16(v_up2);
  
              // Load third row for 3x3 Sobel filter
              v_um = v_load(&n_src[j-1]);
              v_up = v_load(&n_src[j+1]);
              // TODO: Replace _mm_slli_si128 with hal method
              v_un = v_select(v_select_m, v_uint8x16(_mm_slli_si128(v_up.val, 1)),
                                          v_uint8x16(_mm_srli_si128(v_um.val, 1)));
              v_expand(v_um, v_um1, v_um2);
              v_expand(v_un, v_un1, v_un2);
              v_expand(v_up, v_up1, v_up2);
              v_int16x8 v_s3m1 = v_reinterpret_as_s16(v_um1);
              v_int16x8 v_s3m2 = v_reinterpret_as_s16(v_um2);
              v_int16x8 v_s3n1 = v_reinterpret_as_s16(v_un1);
              v_int16x8 v_s3n2 = v_reinterpret_as_s16(v_un2);
              v_int16x8 v_s3p1 = v_reinterpret_as_s16(v_up1);
              v_int16x8 v_s3p2 = v_reinterpret_as_s16(v_up2);
  
              // dx & dy for rows 1, 2, 3
              v_int16x8 v_sdx1, v_sdy1;
              spatialGradientKernel<v_int16x8>( v_sdx1, v_sdy1,
                                                v_s1m1, v_s1n1, v_s1p1,
                                                v_s2m1,         v_s2p1,
                                                v_s3m1, v_s3n1, v_s3p1 );
  
              v_int16x8 v_sdx2, v_sdy2;
              spatialGradientKernel<v_int16x8>( v_sdx2, v_sdy2,
                                                v_s1m2, v_s1n2, v_s1p2,
                                                v_s2m2,         v_s2p2,
                                                v_s3m2, v_s3n2, v_s3p2 );
  
              // Store
              v_store(&c_dx[j],   v_sdx1);
              v_store(&c_dx[j+8], v_sdx2);
              v_store(&c_dy[j],   v_sdy1);
              v_store(&c_dy[j+8], v_sdy2);
  
              // Load fourth row for 3x3 Sobel filter
              v_um = v_load(&m_src[j-1]);
              v_up = v_load(&m_src[j+1]);
              // TODO: Replace _mm_slli_si128 with hal method
              v_un = v_select(v_select_m, v_uint8x16(_mm_slli_si128(v_up.val, 1)),
                                          v_uint8x16(_mm_srli_si128(v_um.val, 1)));
              v_expand(v_um, v_um1, v_um2);
              v_expand(v_un, v_un1, v_un2);
              v_expand(v_up, v_up1, v_up2);
              v_int16x8 v_s4m1 = v_reinterpret_as_s16(v_um1);
              v_int16x8 v_s4m2 = v_reinterpret_as_s16(v_um2);
              v_int16x8 v_s4n1 = v_reinterpret_as_s16(v_un1);
              v_int16x8 v_s4n2 = v_reinterpret_as_s16(v_un2);
              v_int16x8 v_s4p1 = v_reinterpret_as_s16(v_up1);
              v_int16x8 v_s4p2 = v_reinterpret_as_s16(v_up2);
  
              // dx & dy for rows 2, 3, 4
              spatialGradientKernel<v_int16x8>( v_sdx1, v_sdy1,
                                                v_s2m1, v_s2n1, v_s2p1,
                                                v_s3m1,         v_s3p1,
                                                v_s4m1, v_s4n1, v_s4p1 );
  
              spatialGradientKernel<v_int16x8>( v_sdx2, v_sdy2,
                                                v_s2m2, v_s2n2, v_s2p2,
                                                v_s3m2,         v_s3p2,
                                                v_s4m2, v_s4n2, v_s4p2 );
  
              // Store
              v_store(&n_dx[j],   v_sdx1);
              v_store(&n_dx[j+8], v_sdx2);
              v_store(&n_dy[j],   v_sdy1);
              v_store(&n_dy[j+8], v_sdy2);
          }
      }
      i_start = i;
      j_start = j;
  #endif
      int j_p, j_n;
      uchar v00, v01, v02, v10, v11, v12, v20, v21, v22;
      for ( i = 0; i < H; i++ )
      {
          if   ( i == 0 ) p_src = src.ptr<uchar>(i_top);
          else            p_src = src.ptr<uchar>(i-1);
  
          c_src = src.ptr<uchar>(i);
  
          if ( i == H - 1 ) n_src = src.ptr<uchar>(i_bottom);
          else              n_src = src.ptr<uchar>(i+1);
  
          c_dx = dx.ptr<short>(i);
          c_dy = dy.ptr<short>(i);
  
          // Process left-most column
          j = 0;
          j_p = j + j_offl;
          j_n = 1;
          if ( j_n >= W ) j_n = j + j_offr;
          v00 = p_src[j_p]; v01 = p_src[j]; v02 = p_src[j_n];
          v10 = c_src[j_p]; v11 = c_src[j]; v12 = c_src[j_n];
          v20 = n_src[j_p]; v21 = n_src[j]; v22 = n_src[j_n];
          spatialGradientKernel<short>( c_dx[0], c_dy[0], v00, v01, v02, v10,
                                        v12, v20, v21, v22 );
          v00 = v01; v10 = v11; v20 = v21;
          v01 = v02; v11 = v12; v21 = v22;
  
          // Process middle columns
          j = i >= i_start ? 1 : j_start;
          j_p = j - 1;
          v00 = p_src[j_p]; v01 = p_src[j];
          v10 = c_src[j_p]; v11 = c_src[j];
          v20 = n_src[j_p]; v21 = n_src[j];
  
          for ( ; j < W - 1; j++ )
          {
              // Get values for next column
              j_n = j + 1; v02 = p_src[j_n]; v12 = c_src[j_n]; v22 = n_src[j_n];
              spatialGradientKernel<short>( c_dx[j], c_dy[j], v00, v01, v02, v10,
                                            v12, v20, v21, v22 );
  
              // Move values back one column for next iteration
              v00 = v01; v10 = v11; v20 = v21;
              v01 = v02; v11 = v12; v21 = v22;
          }
  
          // Process right-most column
          if ( j < W )
          {
              j_n = j + j_offr; v02 = p_src[j_n]; v12 = c_src[j_n]; v22 = n_src[j_n];
              spatialGradientKernel<short>( c_dx[j], c_dy[j], v00, v01, v02, v10,
                                            v12, v20, v21, v22 );
          }
      }
  
  }
  
  }
  