lily/scale.cc

   1 /*
   2   scale.cc -- implement Scale
   3
   4   source file of the GNU LilyPond music typesetter
   5
   6   (c) 2006--2007 Han-Wen Nienhuys <hanwen@lilypond.org>
   7       2007--2008 Rune Zedeler
   8       2008       Joe Neeman <joeneeman@gmail.com>
   9 */
  10
  11 #include "scale.hh"
  12
  13 #include "ly-smobs.icc"
  14
  15 /*
  16   todo: put string <-> pitch here too.
  17
  18 */
  19 LY_DEFINE (ly_make_scale, "ly:make-scale",
  20            1, 0, 0, (SCM steps),
  21            "Create a scale. "
  22            "The argument is a vector of rational numbers, each of which "
  23            "represents the number of tones of a pitch above the tonic.")
  24 {
  25   bool type_ok = scm_is_vector (steps);
  26
  27   vector<Rational> tones;
  28   if (type_ok)
  29     {
  30       int len = scm_c_vector_length (steps);
  31       for (int i = 0 ; i < len; i++)
  32         {
  33           SCM step = scm_c_vector_ref (steps, i);
  34           type_ok = type_ok && scm_is_rational (step);
  35           if (type_ok)
  36             {
  37               Rational from_c (scm_to_int (scm_numerator (step)),
  38                                scm_to_int (scm_denominator (step)));
  39               tones.push_back (from_c);
  40             }
  41         }
  42     }
  43
  44
  45   SCM_ASSERT_TYPE (type_ok, steps, SCM_ARG1, __FUNCTION__, "vector of rational");
  46
  47   Scale *s = new Scale (tones);
  48
  49   SCM retval =  s->self_scm ();
  50   s->unprotect ();
  51
  52   return retval;
  53 }
  54
  55 LY_DEFINE (ly_default_scale, "ly:default-scale",
  56            0, 0, 0, (),
  57            "Get the global default scale.")
  58 {
  59   return default_global_scale
  60     ? SCM_BOOL_F
  61     : default_global_scale->self_scm ();
  62 }
  63
  64
  65 Scale * default_global_scale = 0;
  66
  67 LY_DEFINE (ly_set_default_scale, "ly:set-default-scale",
  68            1, 0, 0, (SCM scale),
  69            "Set the global default scale.")
  70 {
  71   LY_ASSERT_SMOB (Scale, scale, 1);
  72
  73   Scale *s = Scale::unsmob (scale);
  74   if (default_global_scale)
  75     default_global_scale->unprotect ();
  76   default_global_scale = s;
  77   s->protect ();
  78
  79   return SCM_UNSPECIFIED;
  80 }
  81
  82 int
  83 Scale::step_count () const
  84 {
  85   return step_tones_.size ();
  86 }
  87
  88 Rational
  89 Scale::tones_at_step (int step, int octave) const
  90 {
  91   int normalized_step = normalize_step (step);
  92
  93   octave += (step - normalized_step) / step_count ();
  94
  95   // There are 6 tones in an octave.
  96   return step_tones_[normalized_step] + Rational (octave*6);
  97 }
  98
  99 Rational
 100 Scale::step_size (int step) const
 101 {
 102   int normalized_step = normalize_step (step);
 103
 104   // Wrap around if we are asked for the final note of the
 105   // scale (6 is the number of tones of the octave above the
 106   // first note).
 107   if (normalized_step + 1 == step_count ())
 108     return Rational(6) - step_tones_[normalized_step];
 109
 110   return step_tones_[normalized_step + 1] - step_tones_[normalized_step];
 111 }
 112
 113 int
 114 Scale::normalize_step (int step) const
 115 {
 116   int ret = step % step_count ();
 117   if (ret < 0)
 118     ret += step_count ();
 119
 120   return ret;
 121 }
 122
 123 int
 124 Scale::print_smob (SCM x, SCM port, scm_print_state *)
 125 {
 126   (void) x;
 127
 128   scm_puts ("#<Scale>", port);
 129   return 1;
 130 }
 131
 132
 133 SCM
 134 Scale::mark_smob (SCM x)
 135 {
 136   (void) x;
 137   return SCM_UNSPECIFIED;
 138 }
 139
 140 Scale::Scale (vector<Rational> const &tones)
 141 {
 142   step_tones_ = tones;
 143
 144   smobify_self ();
 145 }
 146
 147 Scale::Scale (Scale const &src)
 148 {
 149   step_tones_ = src.step_tones_;
 150   smobify_self ();
 151 }
 152
 153
 154 Scale::~Scale ()
 155 {
 156 }
 157
 158 IMPLEMENT_SMOBS (Scale);
 159 IMPLEMENT_DEFAULT_EQUAL_P (Scale);