1 files changed, 101 insertions, 0 deletions
diff --git a/gsl-1.9/fft/bitreverse.c b/gsl-1.9/fft/bitreverse.c
new file mode 100644
index 0000000..15e0e8a
--- /dev/null
+++ b/gsl-1.9/fft/bitreverse.c
@@ -0,0 +1,101 @@
+/* fft/bitreverse.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 <gsl/gsl_fft.h>
+
+#include "complex_internal.h"
+#include "bitreverse.h"
+
+static int 
+FUNCTION(fft_complex,bitreverse_order) (BASE data[], 
+                                        const size_t stride,
+                                        const size_t n,
+                                        size_t logn)
+{
+  /* This is the Goldrader bit-reversal algorithm */
+
+  size_t i;
+  size_t j = 0;
+
+  logn = 0 ; /* not needed for this algorithm */
+
+  for (i = 0; i < n - 1; i++)
+    {
+      size_t k = n / 2 ;
+
+      if (i < j)
+        {
+          const BASE tmp_real = REAL(data,stride,i);
+          const BASE tmp_imag = IMAG(data,stride,i);
+          REAL(data,stride,i) = REAL(data,stride,j);
+          IMAG(data,stride,i) = IMAG(data,stride,j);
+          REAL(data,stride,j) = tmp_real;
+          IMAG(data,stride,j) = tmp_imag;
+        }
+
+      while (k <= j) 
+        {
+          j = j - k ;
+          k = k / 2 ;
+        }
+
+      j += k ;
+    }
+
+  return 0;
+}
+
+
+static int 
+FUNCTION(fft_real,bitreverse_order) (BASE data[], 
+                                const size_t stride, 
+                                const size_t n,
+                                size_t logn)
+{
+  /* This is the Goldrader bit-reversal algorithm */
+
+  size_t i;
+  size_t j = 0;
+
+  logn = 0 ; /* not needed for this algorithm */
+
+  for (i = 0; i < n - 1; i++)
+    {
+      size_t k = n / 2 ;
+
+      if (i < j)
+        {
+          const BASE tmp = VECTOR(data,stride,i);
+          VECTOR(data,stride,i) = VECTOR(data,stride,j);
+          VECTOR(data,stride,j) = tmp;
+        }
+
+      while (k <= j) 
+        {
+          j = j - k ;
+          k = k / 2 ;
+        }
+
+      j += k ;
+    }
+
+  return 0;
+}
+