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reverse.cc

/*
    Copyright (C) 2004 Paul Davis 

    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., 675 Mass Ave, Cambridge, MA 02139, USA.

*/

#include <algorithm>

#include <pbd/basename.h>

#include <ardour/types.h>
#include <ardour/reverse.h>
#include <ardour/audiofilesource.h>
#include <ardour/session.h>
#include <ardour/audioregion.h>

#include "i18n.h"

using namespace std;
using namespace ARDOUR;

Reverse::Reverse (Session& s)
      : AudioFilter (s)
{
}

Reverse::~Reverse ()
{
}

int
Reverse::run (boost::shared_ptr<AudioRegion> region)
{
      SourceList nsrcs;
      SourceList::iterator si;
      nframes_t blocksize = 256 * 1024;
      Sample* buf = 0;
      nframes_t fpos;
      nframes_t fstart;
      nframes_t to_read;
      int ret = -1;

      /* create new sources */

      if (make_new_sources (region, nsrcs)) {
            goto out;
      }

      fstart = region->start();

      if (blocksize > region->length()) {
            blocksize = region->length();
      }

      fpos = max (fstart, (fstart + region->length() - blocksize));
      buf = new Sample[blocksize];
      to_read = blocksize;

      /* now read it backwards */

      while (to_read) {

            uint32_t n;

            for (n = 0, si = nsrcs.begin(); n < region->n_channels(); ++n, ++si) {

                  /* read it in */
                  
                  if (region->source (n)->read (buf, fpos, to_read) != to_read) {
                        goto out;
                  }

                  /* swap memory order */
                  
                  for (nframes_t i = 0; i < to_read/2; ++i) {
                        swap (buf[i],buf[to_read-1-i]);
                  }
                  
                  /* write it out */

                  if ((*si)->write (buf, to_read) != to_read) {
                        goto out;
                  }
            }

            if (fpos > fstart + blocksize) {
                  fpos -= to_read;
                  to_read = blocksize;
            } else {
                  to_read = fpos - fstart;
                  fpos = fstart;
            }
      };

      ret = finish (region, nsrcs);

  out:

      if (buf) {
            delete [] buf;
      }

      if (ret) {
            for (si = nsrcs.begin(); si != nsrcs.end(); ++si) {
                  (*si)->mark_for_remove ();
            }
      }
      
      return ret;
}

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