text: import os
  import torch
  from torch.utils.ffi import create_extension
  # from torch.utils.cpp_extension import BuildExtension
  
  
  sources = ['src/dcn_v2.c']
  headers = ['src/dcn_v2.h']
  defines = []
  with_cuda = False
  
  extra_objects = []
  if torch.cuda.is_available():
      print('Including CUDA code.')
      sources += ['src/dcn_v2_cuda.c']
      headers += ['src/dcn_v2_cuda.h']
      defines += [('WITH_CUDA', None)]
      extra_objects += ['src/cuda/dcn_v2_im2col_cuda.cu.o']
      extra_objects += ['src/cuda/dcn_v2_psroi_pooling_cuda.cu.o']
      with_cuda = True
  else:
      raise ValueError('CUDA is not available')
  
  extra_compile_args = ['-fopenmp', '-std=c99']
  
  this_file = os.path.dirname(os.path.realpath(__file__))
  print(this_file)
  sources = [os.path.join(this_file, fname) for fname in sources]
  headers = [os.path.join(this_file, fname) for fname in headers]
  extra_objects = [os.path.join(this_file, fname) for fname in extra_objects]
  
  
  # ffi = BuildExtension(
  ffi = create_extension(
      '_ext.dcn_v2',
      headers=headers,
      sources=sources,
      define_macros=defines,
      relative_to=__file__,
      with_cuda=with_cuda,
      extra_objects=extra_objects,
      extra_compile_args=extra_compile_args
  )
  
  if __name__ == '__main__':
      ffi.build()
  