1 files changed, 145 insertions, 0 deletions
diff --git a/gsl-1.9/fft/real_main.c b/gsl-1.9/fft/real_main.c
new file mode 100644
index 0000000..47919a9
--- /dev/null
+++ b/gsl-1.9/fft/real_main.c
@@ -0,0 +1,145 @@
+/* fft/real_main.c
+ * 
+ * Copyright (C) 1996, 1997, 1998, 1999, 2000 Brian Gough
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or (at
+ * your option) any later version.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ */
+
+#include <config.h>
+#include <stdlib.h>
+#include <math.h>
+
+#include <gsl/gsl_errno.h>
+#include <gsl/gsl_complex.h>
+#include <gsl/gsl_fft_real.h>
+
+#include "real_pass.h"
+
+int
+FUNCTION(gsl_fft_real,transform) (BASE data[], const size_t stride, const size_t n,
+                                  const TYPE(gsl_fft_real_wavetable) * wavetable,
+                                  TYPE(gsl_fft_real_workspace) * work)
+{
+  const size_t nf = wavetable->nf;
+
+  size_t i;
+
+  size_t q, product = 1;
+  size_t tskip;
+  size_t product_1;
+
+  BASE *const scratch = work->scratch;
+  TYPE(gsl_complex) *twiddle1, *twiddle2, *twiddle3, *twiddle4;
+
+  size_t state = 0;
+  BASE *in = data;
+  size_t istride = stride ;
+  BASE *out = scratch;
+  size_t ostride = 1 ;
+  
+  if (n == 0)
+    {
+      GSL_ERROR ("length n must be positive integer", GSL_EDOM);
+    }
+
+  if (n == 1)
+    {                           /* FFT of one data point is the identity */
+      return 0;
+    }
+
+  if (n != wavetable->n)
+    {
+      GSL_ERROR ("wavetable does not match length of data", GSL_EINVAL);
+    }
+
+  if (n != work->n)
+    {
+      GSL_ERROR ("workspace does not match length of data", GSL_EINVAL);
+    }
+
+  for (i = 0; i < nf; i++)
+    {
+      const size_t factor = wavetable->factor[i];
+      product_1 = product;
+      product *= factor;
+      q = n / product;
+
+      tskip = (product_1 + 1) / 2 - 1;
+
+      if (state == 0)
+        {
+          in = data;
+          istride = stride;
+          out = scratch;
+          ostride = 1;
+          state = 1;
+        }
+      else
+        {
+          in = scratch;
+          istride = 1;
+          out = data;
+          ostride = stride;
+          state = 0;
+        }
+
+      if (factor == 2)
+        {
+          twiddle1 = wavetable->twiddle[i];
+          FUNCTION(fft_real,pass_2) (in, istride, out, ostride, product, n, twiddle1);
+        }
+      else if (factor == 3)
+        {
+          twiddle1 = wavetable->twiddle[i];
+          twiddle2 = twiddle1 + tskip;
+          FUNCTION(fft_real,pass_3) (in, istride, out, ostride, product, n, twiddle1,
+                               twiddle2);
+        }
+      else if (factor == 4)
+        {
+          twiddle1 = wavetable->twiddle[i];
+          twiddle2 = twiddle1 + tskip;
+          twiddle3 = twiddle2 + tskip;
+          FUNCTION(fft_real,pass_4) (in, istride, out, ostride, product, n, twiddle1,
+                                     twiddle2, twiddle3);
+        }
+      else if (factor == 5)
+        {
+          twiddle1 = wavetable->twiddle[i];
+          twiddle2 = twiddle1 + tskip;
+          twiddle3 = twiddle2 + tskip;
+          twiddle4 = twiddle3 + tskip;
+          FUNCTION(fft_real,pass_5) (in, istride, out, ostride, product, n, twiddle1,
+                                     twiddle2, twiddle3, twiddle4);
+        }
+      else
+        {
+          twiddle1 = wavetable->twiddle[i];
+          FUNCTION(fft_real,pass_n) (in, istride, out, ostride, factor, product, n,
+                                     twiddle1);
+        }
+    }
+
+  if (state == 1)               /* copy results back from scratch to data */
+    {
+      for (i = 0; i < n; i++)
+        {
+          data[stride*i] = scratch[i] ;
+        }
+    }
+
+  return 0;
+
+}