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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.

    $Id: reverse.cc,v 1.6 2005/03/05 16:21:01 gvdo Exp $
*/

#include <algorithm>

#include <pbd/basename.h>

#include <ardour/types.h>
#include <ardour/reverse.h>
#include <ardour/filesource.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 (AudioRegion& region)
{
      AudioRegion::SourceList nsrcs;
      AudioRegion::SourceList::iterator si;
      const jack_nframes_t blocksize = 256 * 1048;
      Sample buf[blocksize];
      jack_nframes_t fpos;
      jack_nframes_t fend;
      jack_nframes_t fstart;
      jack_nframes_t to_read;
      int ret = -1;

      /* create new sources */

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

      fend = region.start() + region.length();
      fstart = region.start();

      if (blocksize < fend) {
            fpos =max(fstart, fend - blocksize);
      } else {
            fpos = fstart;
      }

      to_read = min (region.length(), blocksize);

      /* now read it backwards */

      while (1) {

            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 (jack_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) {
                  break;
            } else if (fpos > fstart + to_read) {
                  fpos -= to_read;
                  to_read = min (fstart - fpos, blocksize);
            } else {
                  to_read = fpos-fstart;
                  fpos = fstart;
            }
      };

      ret = finish (region, nsrcs);

  out:

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

      return ret;
}

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