- cufinufft1d.cu
  This file contains the execution functions 1d type 1,2 that are called in ../cufinufft.cu

- spreadinterp1d.cu
  This file contains all the GPU kernels for 1d spreading, interpolation.

- interp1d_wrapper.cu
  Wrappers for 1d interpolations. One method is implemented:
    (1) nonuniform driven,

- spread1d_wrapper.cu
  Wrappers for 1d spreading. Two methods are implemented:
    (1) nonuniform driven,
    (2) subproblem
