1 files changed, 106 insertions, 0 deletions
diff --git a/gsl-1.9/fft/hc_pass_2.c b/gsl-1.9/fft/hc_pass_2.c
new file mode 100644
index 0000000..2cb448e
--- /dev/null
+++ b/gsl-1.9/fft/hc_pass_2.c
@@ -0,0 +1,106 @@
+/* fft/hc_pass_2.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.
+ */
+
+static void
+FUNCTION(fft_halfcomplex,pass_2) (const BASE in[],
+                                  const size_t istride,
+                                  BASE out[],
+                                  const size_t ostride,
+                                  const size_t product,
+                                  const size_t n,
+                                  const TYPE(gsl_complex) twiddle[])
+{
+  size_t i, j, k, k1, jump;
+  size_t factor, q, m, product_1;
+  i = 0;
+  j = 0;
+
+  factor = 2;
+  m = n / factor;
+  q = n / product;
+  product_1 = product / factor;
+  jump = (factor - 1) * q;
+
+  for (k1 = 0; k1 < product_1; k1++)
+    {
+      const ATOMIC r0 = VECTOR(in,istride,2 * k1 * q);
+      const ATOMIC r1 = VECTOR(in,istride,2 * k1 * q + 2 * q - 1);
+
+      const ATOMIC s0 = r0 + r1;
+      const ATOMIC s1 = r0 - r1;
+
+      VECTOR(out,ostride,q * k1) = s0;
+      VECTOR(out,ostride,q * k1 + m) = s1;
+    }
+
+  if (q == 1)
+    return;
+
+  for (k = 1; k < (q + 1) / 2; k++)
+    {
+      const ATOMIC w_real = GSL_REAL(twiddle[k - 1]);
+      const ATOMIC w_imag = GSL_IMAG(twiddle[k - 1]);
+
+      for (k1 = 0; k1 < product_1; k1++)
+        {
+          const size_t from0 = 2 * k1 * q + 2 * k - 1;
+          const size_t from1 = 2 * k1 * q - 2 * k + 2 * q - 1;
+
+          const ATOMIC z0_real = VECTOR(in,istride,from0);
+          const ATOMIC z0_imag = VECTOR(in,istride,from0 + 1);
+
+          const ATOMIC z1_real = VECTOR(in,istride,from1);
+          const ATOMIC z1_imag = VECTOR(in,istride,from1 + 1);
+
+          /* compute x = W(2) z */
+
+          /* x0 = z0 + z1 */
+          const ATOMIC x0_real = z0_real + z1_real;
+          const ATOMIC x0_imag = z0_imag - z1_imag;
+
+          /* x1 = z0 - z1 */
+          const ATOMIC x1_real = z0_real - z1_real;
+          const ATOMIC x1_imag = z0_imag + z1_imag;
+
+          const size_t to0 = k1 * q + 2 * k - 1;
+          const size_t to1 = to0 + m;
+
+          VECTOR(out,ostride,to0) = x0_real;
+          VECTOR(out,ostride,to0 + 1) = x0_imag;
+
+          VECTOR(out,ostride,to1) = w_real * x1_real - w_imag * x1_imag;
+          VECTOR(out,ostride,to1 + 1) = w_imag * x1_real + w_real * x1_imag;
+
+        }
+    }
+
+  if (q % 2 == 1)
+    return;
+
+  for (k1 = 0; k1 < product_1; k1++)
+    {
+      const size_t from0 = 2 * k1 * q + q - 1;
+      const size_t to0 = k1 * q + q - 1;
+      const size_t to1 = to0 + m;
+
+      VECTOR(out,ostride,to0) = 2 * VECTOR(in,istride,from0);
+      VECTOR(out,ostride,to1) = -2 * VECTOR(in,istride,from0 + 1);
+    }
+  return;
+}