Move FFT stuff to extra source file.

Signed-off-by: Stefan Westerfeld <stefan@space.twc.de>

src/Makefile.am

 bin_PROGRAMS = audiowmark
 
-audiowmark_SOURCES = audiowmark.cc wavdata.cc
+audiowmark_SOURCES = audiowmark.cc wavdata.cc fft.cc
 audiowmark_LDFLAGS = $(SNDFILE_LIBS) $(FFTW_LIBS)

src/audiowmark.cc

@@ -4,8 +4,7 @@
 #include <random>
 #include <complex>
 
-#include <fftw3.h>
-
+#include "fft.hh"
 #include "wavdata.hh"
 
 using std::string;
@@ -70,52 +69,6 @@ get_frame (WavData& wav_data, int f, int ch)
   return result;
 }
 
-float *
-new_array_float (size_t N)
-{
-  const size_t N_2 = N + 2; /* extra space for r2c extra complex output */
-
-  return (float *) fftwf_malloc (sizeof (float) * N_2);
-}
-
-void
-free_array_float (float *f)
-{
-  fftwf_free (f);
-}
-
-void
-fftar_float (size_t N, float *in, float *out)
-{
-  static fftwf_plan plan = nullptr; // FIXME: should be one plan per fft size
-
-  if (!plan)
-    {
-      float *plan_in = new_array_float (N);
-      float *plan_out = new_array_float (N);
-      plan = fftwf_plan_dft_r2c_1d (N, plan_in, (fftwf_complex *) plan_out, FFTW_ESTIMATE | FFTW_PRESERVE_INPUT);
-
-      // we add code for saving plans here, and use patient planning
-    }
-  fftwf_execute_dft_r2c (plan, in, (fftwf_complex *) out);
-}
-
-void
-fftsr_float (size_t N, float *in, float *out)
-{
-  static fftwf_plan plan = nullptr; // FIXME: should be one plan per fft size
-
-  if (!plan)
-    {
-      float *plan_in = new_array_float (N);
-      float *plan_out = new_array_float (N);
-      plan = fftwf_plan_dft_c2r_1d (N, (fftwf_complex *) plan_in, plan_out, FFTW_ESTIMATE | FFTW_PRESERVE_INPUT);
-
-      // we add code for saving plans here, and use patient planning
-    }
-  fftwf_execute_dft_c2r (plan, (fftwf_complex *)in, out);
-}
-
 void
 get_up_down (int f, vector<int>& up, vector<int>& down)
 {
@@ -193,48 +146,6 @@ bit_vec_to_str (const vector<int>& bit_vec)
   return bit_str;
 }
 
-vector<complex<float>>
-fft (const vector<float>& in)
-{
-  vector<complex<float>> out (in.size() / 2 + 1);
-
-  /* ensure memory is SSE-aligned (or other vectorized stuff) */
-  float *fft_in = new_array_float (in.size());
-  float *fft_out = new_array_float (in.size());
-
-  std::copy (in.begin(), in.end(), fft_in);
-  fftar_float (in.size(), fft_in, fft_out);
-
-  /* complex<float> vector and fft_out have the same layout in memory */
-  std::copy (fft_out, fft_out + out.size() * 2, reinterpret_cast<float *> (&out[0]));
-
-  free_array_float (fft_out);
-  free_array_float (fft_in);
-
-  return out;
-}
-
-vector<float>
-ifft (const vector<complex<float>>& in)
-{
-  vector<float> out ((in.size() - 1) * 2);
-
-  /* ensure memory is SSE-aligned (or other vectorized stuff) */
-  float *ifft_in = new_array_float (out.size());
-  float *ifft_out = new_array_float (out.size());
-
-  /* complex<float> vector and fft_out have the same layout in memory */
-  std::copy (in.begin(), in.end(), reinterpret_cast<complex<float> *> (ifft_in));
-  fftsr_float (out.size(), ifft_in, ifft_out);
-
-  std::copy (ifft_out, ifft_out + out.size(), &out[0]);
-
-  free_array_float (ifft_out);
-  free_array_float (ifft_in);
-
-  return out;
-}
-
 int
 add_watermark (const string& infile, const string& outfile, const string& bits)
 {