cannam@127: /*
cannam@127:  * Copyright (c) 2003, 2007-14 Matteo Frigo
cannam@127:  * Copyright (c) 2003, 2007-14 Massachusetts Institute of Technology
cannam@127:  *
cannam@127:  * This program is free software; you can redistribute it and/or modify
cannam@127:  * it under the terms of the GNU General Public License as published by
cannam@127:  * the Free Software Foundation; either version 2 of the License, or
cannam@127:  * (at your option) any later version.
cannam@127:  *
cannam@127:  * This program is distributed in the hope that it will be useful,
cannam@127:  * but WITHOUT ANY WARRANTY; without even the implied warranty of
cannam@127:  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
cannam@127:  * GNU General Public License for more details.
cannam@127:  *
cannam@127:  * You should have received a copy of the GNU General Public License
cannam@127:  * along with this program; if not, write to the Free Software
cannam@127:  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
cannam@127:  *
cannam@127:  */
cannam@127: 
cannam@127: /* routines shared by the various buffered solvers */
cannam@127: 
cannam@127: #include "ifftw.h"
cannam@127: 
cannam@127: #define DEFAULT_MAXNBUF ((INT)256)
cannam@127: 
cannam@127: /* approx. 512KB of buffers for complex data */
cannam@127: #define MAXBUFSZ (256 * 1024 / (INT)(sizeof(R)))
cannam@127: 
cannam@127: INT X(nbuf)(INT n, INT vl, INT maxnbuf)
cannam@127: {
cannam@127:      INT i, nbuf, lb; 
cannam@127: 
cannam@127:      if (!maxnbuf) 
cannam@127: 	  maxnbuf = DEFAULT_MAXNBUF;
cannam@127: 
cannam@127:      nbuf = X(imin)(maxnbuf,
cannam@127: 		    X(imin)(vl, X(imax)((INT)1, MAXBUFSZ / n)));
cannam@127: 
cannam@127:      /*
cannam@127:       * Look for a buffer number (not too small) that divides the
cannam@127:       * vector length, in order that we only need one child plan:
cannam@127:       */
cannam@127:      lb = X(imax)(1, nbuf / 4);
cannam@127:      for (i = nbuf; i >= lb; --i)
cannam@127:           if (vl % i == 0)
cannam@127:                return i;
cannam@127: 
cannam@127:      /* whatever... */
cannam@127:      return nbuf;
cannam@127: }
cannam@127: 
cannam@127: #define SKEW 6 /* need to be even for SIMD */
cannam@127: #define SKEWMOD 8 
cannam@127: 
cannam@127: INT X(bufdist)(INT n, INT vl)
cannam@127: {
cannam@127:      if (vl == 1)
cannam@127: 	  return n;
cannam@127:      else 
cannam@127: 	  /* return smallest X such that X >= N and X == SKEW (mod SKEWMOD) */
cannam@127: 	  return n + X(modulo)(SKEW - n, SKEWMOD);
cannam@127: }
cannam@127: 
cannam@127: int X(toobig)(INT n)
cannam@127: {
cannam@127:      return n > MAXBUFSZ;
cannam@127: }
cannam@127: 
cannam@127: /* TRUE if there exists i < which such that maxnbuf[i] and
cannam@127:    maxnbuf[which] yield the same value, in which case we canonicalize
cannam@127:    on the minimum value */
cannam@127: int X(nbuf_redundant)(INT n, INT vl, size_t which, 
cannam@127: 		      const INT *maxnbuf, size_t nmaxnbuf)
cannam@127: {
cannam@127:      size_t i;
cannam@127:      (void)nmaxnbuf; /* UNUSED */
cannam@127:      for (i = 0; i < which; ++i)
cannam@127: 	  if (X(nbuf)(n, vl, maxnbuf[i]) == X(nbuf)(n, vl, maxnbuf[which]))
cannam@127: 	       return 1;
cannam@127:      return 0;
cannam@127: }