comparison src/fftw-3.3.3/rdft/rdft2-inplace-strides.c @ 10:37bf6b4a2645

Add FFTW3

+/*
+ * Copyright (c) 2003, 2007-11 Matteo Frigo
+ * Copyright (c) 2003, 2007-11 Massachusetts Institute of Technology
+ *
+ * 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 "rdft.h"
+
+/* Check if the vecsz/sz strides are consistent with the problem
+   being in-place for vecsz.dim[vdim], or for all dimensions
+   if vdim == RNK_MINFTY.  We can't just use tensor_inplace_strides
+   because rdft transforms have the unfortunate property of
+   differing input and output sizes.   This routine is not
+   exhaustive; we only return 1 for the most common case.  */
+int X(rdft2_inplace_strides)(const problem_rdft2 *p, int vdim)
+{
+     INT N, Nc;
+     INT rs, cs;
+     int i;
+     
+     for (i = 0; i + 1 < p->sz->rnk; ++i)
+	  if (p->sz->dims[i].is != p->sz->dims[i].os)
+	       return 0;
+
+     if (!FINITE_RNK(p->vecsz->rnk) || p->vecsz->rnk == 0)
+	  return 1;
+     if (!FINITE_RNK(vdim)) { /* check all vector dimensions */
+	  for (vdim = 0; vdim < p->vecsz->rnk; ++vdim)
+	       if (!X(rdft2_inplace_strides)(p, vdim))
+		    return 0;
+	  return 1;
+     }
+
+     A(vdim < p->vecsz->rnk);
+     if (p->sz->rnk == 0)
+	  return(p->vecsz->dims[vdim].is == p->vecsz->dims[vdim].os);
+
+     N = X(tensor_sz)(p->sz);
+     Nc = (N / p->sz->dims[p->sz->rnk-1].n) *
+	  (p->sz->dims[p->sz->rnk-1].n/2 + 1);
+     X(rdft2_strides)(p->kind, p->sz->dims + p->sz->rnk - 1, &rs, &cs);
+
+     /* the factor of 2 comes from the fact that RS is the stride
+	of p->r0 and p->r1, which is twice as large as the strides
+	in the r2r case */
+     return(p->vecsz->dims[vdim].is == p->vecsz->dims[vdim].os
+	    && (X(iabs)(2 * p->vecsz->dims[vdim].os)
+		>= X(imax)(2 * Nc * X(iabs)(cs), N * X(iabs)(rs))));
+}