livetrax/libs/timecode/src/bbt_time.cc

/*
  Copyright (C) 2002-2010 Paul Davis

  This program is free software; you can redistribute it and/or modify it
  under the terms of the GNU Lesser 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 Lesser General Public
  License for more details.
  
  You should have received a copy of the GNU Lesser General Public License
  along with this program; if not, write to the Free Software Foundation,
  Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*/

#include <cmath>
#include <cassert>

#include "timecode/bbt_time.h"

using namespace Timecode;

/* This number doesn't describe the smallest division of a "beat" (which is
   only defined contextually anyway), but rather the smallest division of the the
   divisions of a bar. If using a meter of 4/8, there are 4 divisions per bar, and
   we can divide each one into ticks_per_bar_division pieces; in a separate meter
   (section) of 3/8, there are 3 divisions per bar, each of which can be divided
   into ticks_per_bar_division pieces.

   The number is intended to have as many integer factors as possible so that
   1/Nth divisions are integer numbers of ticks.

   1920 is the largest legal value that be used inside an SMF file, and has many factors.
*/

const double BBT_Time::ticks_per_bar_division = 1920.0;

BBT_Time::BBT_Time (double dbeats)
{
        /* NOTE: this does not construct a BBT time in a canonical form,
           in that beats may be a very large number, and bars will
           always be zero.
        */

	assert (dbeats >= 0);

        bars = 0;
        beats = rint (floor (dbeats));
        ticks = rint (floor (BBT_Time::ticks_per_bar_division * fmod (dbeats, 1.0)));
}