flatland.c

   1 /*
   2
   3   Example of FFI extension I started from:
   4
   5     https://github.com/pytorch/extension-ffi.git
   6
   7   There is this tutorial
   8
   9     https://github.com/pytorch/tutorials/blob/master/Creating%20Extensions%20using%20FFI.md
  10
  11   And TH's Tensor definition are here in my install:
  12
  13     anaconda3/lib/python3.5/site-packages/torch/lib/include/TH/generic/THTensor.h
  14
  15  */
  16
  17 #include <TH/TH.h>
  18
  19 #include "sequence_generator.h"
  20
  21 THByteTensor *generate_sequence(long nb_sequences, long nb_images_per_sequence, long image_width, long image_height) {
  22   long nb_channels = 3;
  23   unsigned char *a, *b;
  24   long s, c, k, i, j, st0, st1, st2, st3, st4;
  25
  26   THLongStorage *size = THLongStorage_newWithSize(5);
  27   size->data[0] = nb_sequences;
  28   size->data[1] = nb_images_per_sequence;
  29   size->data[2] = nb_channels;
  30   size->data[3] = image_height;
  31   size->data[4] = image_width;
  32
  33   THByteTensor *result = THByteTensor_newWithSize(size, NULL);
  34
  35   THLongStorage_free(size);
  36
  37   st0 = THByteTensor_stride(result, 0);
  38   st1 = THByteTensor_stride(result, 1);
  39   st2 = THByteTensor_stride(result, 2);
  40   st3 = THByteTensor_stride(result, 3);
  41   st4 = THByteTensor_stride(result, 4);
  42
  43   unsigned char tmp_buffer[nb_images_per_sequence * nb_channels * image_width * image_height];
  44
  45   for(s = 0; s < nb_sequences; s++) {
  46     a =
  47       THByteTensor_storage(result)->data + THByteTensor_storageOffset(result) + s * st0;
  48
  49     fl_generate_sequences(1, nb_images_per_sequence, image_width, image_height, tmp_buffer);
  50
  51     unsigned char *r = tmp_buffer;
  52     for(k = 0; k < nb_images_per_sequence; k++) {
  53       for(c = 0; c < nb_channels; c++) {
  54         for(i = 0; i < image_height; i++) {
  55           b = a
  56             + k * st1 + c * st2 + i * st3;
  57           for(j = 0; j < image_width; j++) {
  58             *b = (unsigned char) (*r);
  59             r++;
  60             b += st4;
  61           }
  62         }
  63       }
  64     }
  65   }
  66
  67   return result;
  68 }