1/*M///////////////////////////////////////////////////////////////////////////////////////
2//
3//  IMPORTANT: READ BEFORE DOWNLOADING, COPYING, INSTALLING OR USING.
4//
5//  By downloading, copying, installing or using the software you agree to this license.
6//  If you do not agree to this license, do not download, install,
7//  copy or use the software.
8//
9//
10//                           License Agreement
11//                For Open Source Computer Vision Library
12//
13// Copyright (C) 2013, OpenCV Foundation, all rights reserved.
14// Third party copyrights are property of their respective owners.
15//
16// Redistribution and use in source and binary forms, with or without modification,
17// are permitted provided that the following conditions are met:
18//
19//   * Redistribution's of source code must retain the above copyright notice,
20//     this list of conditions and the following disclaimer.
21//
22//   * Redistribution's in binary form must reproduce the above copyright notice,
23//     this list of conditions and the following disclaimer in the documentation
24//     and/or other materials provided with the distribution.
25//
26//   * The name of the copyright holders may not be used to endorse or promote products
27//     derived from this software without specific prior written permission.
28//
29// This software is provided by the copyright holders and contributors "as is" and
30// any express or implied warranties, including, but not limited to, the implied
31// warranties of merchantability and fitness for a particular purpose are disclaimed.
32// In no event shall the Intel Corporation or contributors be liable for any direct,
33// indirect, incidental, special, exemplary, or consequential damages
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40//M*/
41
42__kernel void im2col(__global const T *im_src, int im_src_offset,
43                     int channels, int height_inp, int width_inp,
44                     int kernel_h, int kernel_w, int pad_h, int pad_w, int stride_h, int stride_w,
45                     int height_out, int width_out,
46                     __global T *im_col, int im_col_offset
47                    )
48{
49    int index = get_global_id(0);
50    if (index >= height_out * width_out * channels)
51        return;
52    int j_out = index % width_out;
53    int i_out = (index / width_out) % height_out;
54    int c_inp = (index / width_out) / height_out;
55
56    int c_out = c_inp * kernel_h * kernel_w;
57    int i_inp = i_out * stride_h - pad_h;
58    int j_inp = j_out * stride_w - pad_w;
59
60    im_src += (c_inp * height_inp + i_inp) * width_inp + j_inp + im_src_offset;
61    im_col += (c_out * height_out + i_out) * width_out + j_out + im_col_offset;
62
63    for (int ki = 0; ki < kernel_h; ++ki)
64        for (int kj = 0; kj < kernel_w; ++kj) {
65            int i = i_inp + ki;
66            int j = j_inp + kj;
67            *im_col = (i >= 0 && j >= 0 && i < height_inp && j < width_inp) ?
68                im_src[ki * width_inp + kj] : 0;
69            im_col += height_out * width_out;
70      }
71}
72