lily/duration.cc

   1 /*
   2   This file is part of LilyPond, the GNU music typesetter.
   3
   4   Copyright (C) 1997--2011 Jan Nieuwenhuizen <janneke@gnu.org>
   5   Han-Wen Nienhuys <hanwen@xs4all.nl>
   6
   7   LilyPond is free software: you can redistribute it and/or modify
   8   it under the terms of the GNU General Public License as published by
   9   the Free Software Foundation, either version 3 of the License, or
  10   (at your option) any later version.
  11
  12   LilyPond is distributed in the hope that it will be useful,
  13   but WITHOUT ANY WARRANTY; without even the implied warranty of
  14   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15   GNU General Public License for more details.
  16
  17   You should have received a copy of the GNU General Public License
  18   along with LilyPond.  If not, see <http://www.gnu.org/licenses/>.
  19 */
  20
  21 #include "duration.hh"
  22
  23 #include "misc.hh"
  24 #include "lily-proto.hh"
  25
  26 #include "ly-smobs.icc"
  27
  28 int
  29 Duration::compare (Duration const &left, Duration const &right)
  30 {
  31   return Rational::compare (left.get_length (), right.get_length ());
  32 }
  33
  34 Duration::Duration ()
  35 {
  36   durlog_ = 0;
  37   dots_ = 0;
  38   factor_ = Rational (1, 1);
  39 }
  40
  41 Duration::Duration (int log, int d)
  42 {
  43   durlog_ = log;
  44   dots_ = d;
  45   factor_ = Rational (1, 1);
  46 }
  47
  48 Duration::Duration (Rational r, bool scale)
  49 {
  50   factor_ = Rational (1, 1);
  51
  52   if (r.num () == 0.0)
  53     {
  54       durlog_ = 0;
  55       dots_ = 0;
  56     }
  57   else
  58     {
  59       /* we want to find the integer k for which 2q/p > 2^k >= q/p.
  60          It's simple to check that k' = \floor \log q - \floor \log p
  61          satisfies the left inequality and is within a factor of 2 of
  62          satistying the right one. Therefore either k = k' or k = k'+1 */
  63
  64       int p = (int) r.num ();
  65       int q = (int) r.den ();
  66       int k = intlog2 (q) - intlog2 (p);
  67       if (shift_left(p, k) < q)
  68         k++;
  69
  70       assert (shift_left(p, k) >= q && shift_left(p, (k-1)) < q);
  71
  72       /* If we were to write out log (p/q) in base 2, then the position of the
  73          first non-zero bit (ie. k in our notation) would be the durlog
  74          and the number of consecutive 1s after that bit would be the number of
  75          dots */
  76       p = shift_left(p, k) - q;
  77       dots_ = 0;
  78       while ((p *= 2) >= q)
  79         {
  80           p -= q;
  81           dots_++;
  82         }
  83
  84       /* we only go up to 64th notes */
  85       if (k > 6)
  86         {
  87           durlog_ = 6;
  88           dots_ = 0;
  89         }
  90       else
  91         durlog_ = k;
  92
  93       if (scale || k > 6)
  94         factor_ = r / get_length ();
  95     }
  96 }
  97
  98 Duration
  99 Duration::compressed (Rational m) const
 100 {
 101   Duration d (*this);
 102   d.factor_ *= m;
 103   return d;
 104 }
 105
 106 Rational
 107 Duration::get_length () const
 108 {
 109   Rational mom (1 << abs (durlog_));
 110
 111   if (durlog_ > 0)
 112     mom = Rational (1) / mom;
 113
 114   Rational delta = mom;
 115   for (int i = 0; i < dots_; i++)
 116     {
 117       delta /= Rational (2);
 118       mom += delta;
 119     }
 120
 121   return mom * factor_;
 122 }
 123
 124 string
 125 Duration::to_string () const
 126 {
 127   string s;
 128
 129   if (durlog_ < 0)
 130     s = "log = " + ::to_string (durlog_);
 131   else
 132     s = ::to_string (1 << durlog_);
 133
 134   s += ::to_string ('.', dots_);
 135   if (factor_ != Moment (Rational (1, 1)))
 136     s += "*" + factor_.to_string ();
 137   return s;
 138 }
 139
 140 IMPLEMENT_TYPE_P (Duration, "ly:duration?");
 141
 142 SCM
 143 Duration::mark_smob (SCM)
 144 {
 145   return SCM_EOL;
 146 }
 147
 148 IMPLEMENT_SIMPLE_SMOBS (Duration);
 149 int
 150 Duration::print_smob (SCM s, SCM port, scm_print_state *)
 151 {
 152   Duration *r = (Duration *) SCM_CELL_WORD_1 (s);
 153
 154   scm_puts ("#<Duration ", port);
 155   scm_display (ly_string2scm (r->to_string ()), port);
 156   scm_puts (" >", port);
 157
 158   return 1;
 159 }
 160
 161 SCM
 162 Duration::equal_p (SCM a, SCM b)
 163 {
 164   Duration *p = (Duration *) SCM_CELL_WORD_1 (a);
 165   Duration *q = (Duration *) SCM_CELL_WORD_1 (b);
 166
 167   bool eq = p->dots_ == q->dots_
 168     && p->durlog_ == q->durlog_
 169     && p->factor_ == q->factor_;
 170
 171   return eq ? SCM_BOOL_T : SCM_BOOL_F;
 172 }
 173
 174 int
 175 Duration::duration_log () const
 176 {
 177   return durlog_;
 178 }
 179
 180 int
 181 Duration::dot_count () const
 182 {
 183   return dots_;
 184 }