extern "C" {
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#include "im2col.h"
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#include "cuda.h"
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}
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__global__ void im2col_pad_kernel(float *im, int offset,
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int channels, int height, int width,
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int ksize, int stride, float *data_col)
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{
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int c,h,w;
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int height_col = 1 + (height-1) / stride;
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int width_col = 1 + (width-1) / stride;
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int channels_col = channels * ksize * ksize;
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int pad = ksize/2;
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int id = (blockIdx.x + blockIdx.y*gridDim.x) * blockDim.x + threadIdx.x;
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int col_size = height_col*width_col*channels_col;
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if (id >= col_size) return;
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int col_index = id;
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w = id % width_col;
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id /= width_col;
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h = id % height_col;
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id /= height_col;
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c = id % channels_col;
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id /= channels_col;
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int w_offset = c % ksize;
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int h_offset = (c / ksize) % ksize;
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int im_channel = c / ksize / ksize;
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int im_row = h_offset + h * stride - pad;
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int im_col = w_offset + w * stride - pad;
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int im_index = offset + im_col + width*(im_row + height*im_channel);
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float val = (im_row < 0 || im_col < 0 || im_row >= height || im_col >= width) ? 0 : im[im_index];
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data_col[col_index] = val;
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}
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__global__ void im2col_nopad_kernel(float *im, int offset,
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int channels, int height, int width,
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int ksize, int stride, float *data_col)
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{
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int c,h,w;
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int height_col = (height - ksize) / stride + 1;
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int width_col = (width - ksize) / stride + 1;
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int channels_col = channels * ksize * ksize;
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int id = (blockIdx.x + blockIdx.y*gridDim.x) * blockDim.x + threadIdx.x;
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int col_size = height_col*width_col*channels_col;
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if (id >= col_size) return;
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int col_index = id;
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w = id % width_col;
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id /= width_col;
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h = id % height_col;
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id /= height_col;
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c = id % channels_col;
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id /= channels_col;
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int w_offset = c % ksize;
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int h_offset = (c / ksize) % ksize;
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int im_channel = c / ksize / ksize;
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int im_row = h_offset + h * stride;
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int im_col = w_offset + w * stride;
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int im_index = offset + im_col + width*(im_row + height*im_channel);
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float val = (im_row < 0 || im_col < 0 || im_row >= height || im_col >= width) ? 0 : im[im_index];
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data_col[col_index] = val;
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}
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extern "C" void im2col_ongpu(float *im, int offset,
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int channels, int height, int width,
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int ksize, int stride, int pad, float *data_col)
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{
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int height_col = (height - ksize) / stride + 1;
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int width_col = (width - ksize) / stride + 1;
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int channels_col = channels * ksize * ksize;
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if (pad){
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height_col = 1 + (height-1) / stride;
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width_col = 1 + (width-1) / stride;
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}
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size_t n = channels_col*height_col*width_col;
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if(pad)im2col_pad_kernel<<<cuda_gridsize(n),BLOCK>>>(im, offset, channels, height, width, ksize, stride, data_col);
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else im2col_nopad_kernel<<<cuda_gridsize(n),BLOCK>>>(im, offset, channels, height, width, ksize, stride, data_col);
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check_error(cudaPeekAtLastError());
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}
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