First commit - moving from LuaForge to SourceForge

1 files changed, 218 insertions, 0 deletions

diff --git a/src/fftw/twiddle.c b/src/fftw/twiddle.c
new file mode 100644
index 0000000..16e9fd0
--- /dev/null
+++ b/src/fftw/twiddle.c
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+/*
+ * Copyright (c) 1997-1999, 2003 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., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+ *
+ */
+
+/*
+ * twiddle.c -- compute twiddle factors
+ * These are the twiddle factors for *direct* fft.  Flip sign to get
+ * the inverse
+ */
+
+/* $Id: twiddle.c,v 1.1 2008/10/17 06:13:18 scuri Exp $ */
+#include "fftw-int.h"
+#include <math.h>
+#include <stdlib.h>
+#include <limits.h>
+
+#ifndef TRUE
+#define TRUE (1 == 1)
+#endif
+
+#ifndef FALSE
+#define FALSE (1 == 0)
+#endif
+
+#ifdef USE_FFTW_SAFE_MULMOD
+/* compute (x * y) mod p, but watch out for integer overflows; we must
+   have x, y >= 0, p > 0.  This routine is slow. */
+int fftw_safe_mulmod(int x, int y, int p)
+{
+     if (y == 0 || x <= INT_MAX / y)
+	  return((x * y) % p);
+     else {
+	  int y2 = y/2;
+	  return((fftw_safe_mulmod(x, y2, p) +
+		  fftw_safe_mulmod(x, y - y2, p)) % p);
+     }
+}
+#endif /* USE_FFTW_SAFE_MULMOD */
+
+static fftw_complex *fftw_compute_rader_twiddle(int n, int r, int g)
+{
+     FFTW_TRIG_REAL twoPiOverN;
+     int m = n / r;
+     int i, j, gpower;
+     fftw_complex *W;
+
+     twoPiOverN = FFTW_K2PI / (FFTW_TRIG_REAL) n;
+     W = (fftw_complex *) fftw_malloc((r - 1) * m * sizeof(fftw_complex));
+     for (i = 0; i < m; ++i)
+	  for (gpower = 1, j = 0; j < r - 1; ++j,
+		    gpower = MULMOD(gpower, g, r)) {
+	       int k = i * (r - 1) + j;
+	       FFTW_TRIG_REAL
+		   ij = (FFTW_TRIG_REAL) (i * gpower);
+	       c_re(W[k]) = FFTW_TRIG_COS(twoPiOverN * ij);
+	       c_im(W[k]) = FFTW_FORWARD * FFTW_TRIG_SIN(twoPiOverN * ij);
+	  }
+
+     return W;
+}
+
+/*
+ * compute the W coefficients (that is, powers of the root of 1)
+ * and store them into an array.
+ */
+static fftw_complex *fftw_compute_twiddle(int n, const fftw_codelet_desc *d)
+{
+     FFTW_TRIG_REAL twoPiOverN;
+     int i, j;
+     fftw_complex *W;
+
+     twoPiOverN = FFTW_K2PI / (FFTW_TRIG_REAL) n;
+
+     if (!d) {
+	  /* generic codelet, needs all twiddles in order */
+	  W = (fftw_complex *) fftw_malloc(n * sizeof(fftw_complex));
+	  for (i = 0; i < n; ++i) {
+	       c_re(W[i]) = FFTW_TRIG_COS(twoPiOverN * (FFTW_TRIG_REAL) i);
+	       c_im(W[i]) = FFTW_FORWARD * FFTW_TRIG_SIN(twoPiOverN * (FFTW_TRIG_REAL) i);
+	  }
+     } else if (d->type == FFTW_RADER)
+	  W = fftw_compute_rader_twiddle(n, d->size, d->signature);
+     else {
+	  int r = d->size;
+	  int m = n / r, m_alloc;
+	  int r1 = d->ntwiddle;
+	  int istart;
+
+	  if (d->type == FFTW_TWIDDLE) {
+	       istart = 0;
+	       m_alloc = m;
+	  } else if (d->type == FFTW_HC2HC) {
+	       /*
+		* This is tricky, do not change lightly.
+		*/
+	       m = (m + 1) / 2;
+	       m_alloc = m - 1;
+	       istart = 1;
+	  } else {
+	       fftw_die("compute_twiddle: invalid argument\n");
+	       /* paranoia for gcc */
+	       m_alloc = 0;
+	       istart = 0;
+	  }
+
+	  W = (fftw_complex *) fftw_malloc(r1 * m_alloc * sizeof(fftw_complex));
+	  for (i = istart; i < m; ++i)
+	       for (j = 0; j < r1; ++j) {
+		    int k = (i - istart) * r1 + j;
+		    FFTW_TRIG_REAL
+			ij = (FFTW_TRIG_REAL) (i * d->twiddle_order[j]);
+		    c_re(W[k]) = FFTW_TRIG_COS(twoPiOverN * ij);
+		    c_im(W[k]) = FFTW_FORWARD * FFTW_TRIG_SIN(twoPiOverN * ij);
+	       }
+     }
+
+     return W;
+}
+
+/*
+ * these routines implement a simple reference-count-based 
+ * management of twiddle structures
+ */
+static fftw_twiddle *twlist = (fftw_twiddle *) 0;
+int fftw_twiddle_size = 0;	/* total allocated size, for debugging */
+
+/* true if the two codelets can share the same twiddle factors */
+static int compatible(const fftw_codelet_desc *d1, const fftw_codelet_desc *d2)
+{
+     int i;
+
+     /* true if they are the same codelet */
+     if (d1 == d2)
+	  return TRUE;
+
+     /* false if one is null and the other is not */
+     if (!d1 || !d2)
+	  return FALSE;
+
+     /* false if size is different */
+     if (d1->size != d2->size)
+	  return FALSE;
+
+     /* false if different types (FFTW_TWIDDLE/FFTW_HC2HC/FFTW_RADER) */
+     if (d1->type != d2->type)
+	  return FALSE;
+
+     /* false if they need different # of twiddles */
+     if (d1->ntwiddle != d2->ntwiddle)
+	  return FALSE;
+
+     /* false if the twiddle orders are different */
+     for (i = 0; i < d1->ntwiddle; ++i)
+	  if (d1->twiddle_order[i] != d2->twiddle_order[i])
+	       return FALSE;
+
+     return TRUE;
+}
+
+fftw_twiddle *fftw_create_twiddle(int n, const fftw_codelet_desc *d)
+{
+     fftw_twiddle *tw;
+
+     /* lookup this n in the twiddle list */
+     for (tw = twlist; tw; tw = tw->next)
+	  if (n == tw->n && compatible(d, tw->cdesc)) {
+	       ++tw->refcnt;
+	       return tw;
+	  }
+     /* not found --- allocate a new struct twiddle */
+     tw = (fftw_twiddle *) fftw_malloc(sizeof(fftw_twiddle));
+     fftw_twiddle_size += n;
+
+     tw->n = n;
+     tw->cdesc = d;
+     tw->twarray = fftw_compute_twiddle(n, d);
+     tw->refcnt = 1;
+
+     /* enqueue the new struct */
+     tw->next = twlist;
+     twlist = tw;
+
+     return tw;
+}
+
+void fftw_destroy_twiddle(fftw_twiddle * tw)
+{
+     fftw_twiddle **p;
+     --tw->refcnt;
+
+     if (tw->refcnt == 0) {
+	  /* remove from the list of known twiddle factors */
+	  for (p = &twlist; p; p = &((*p)->next))
+	       if (*p == tw) {
+		    *p = tw->next;
+		    fftw_twiddle_size -= tw->n;
+		    fftw_free(tw->twarray);
+		    fftw_free(tw);
+		    return;
+	       }
+	  fftw_die("BUG in fftw_destroy_twiddle\n");
+     }
+}