lily/scale.cc

   1 /*
   2   scale.cc -- implement Scale
   3
   4   source file of the GNU LilyPond music typesetter
   5
   6   (c) 2006--2009 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 200 cent tones of a pitch above the"
  24            " tonic.")
  25 {
  26   bool type_ok = scm_is_vector (steps);
  27
  28   vector<Rational> tones;
  29   if (type_ok)
  30     {
  31       int len = scm_c_vector_length (steps);
  32       for (int i = 0 ; i < len; i++)
  33         {
  34           SCM step = scm_c_vector_ref (steps, i);
  35           type_ok = type_ok && scm_is_rational (step);
  36           if (type_ok)
  37             {
  38               Rational from_c (scm_to_int (scm_numerator (step)),
  39                                scm_to_int (scm_denominator (step)));
  40               tones.push_back (from_c);
  41             }
  42         }
  43     }
  44
  45
  46   SCM_ASSERT_TYPE (type_ok, steps, SCM_ARG1, __FUNCTION__, "vector of rational");
  47
  48   Scale *s = new Scale (tones);
  49
  50   SCM retval =  s->self_scm ();
  51   s->unprotect ();
  52
  53   return retval;
  54 }
  55
  56 LY_DEFINE (ly_default_scale, "ly:default-scale",
  57            0, 0, 0, (),
  58            "Get the global default scale.")
  59 {
  60   return default_global_scale
  61     ? default_global_scale->self_scm ()
  62     : SCM_BOOL_F;
  63 }
  64
  65
  66 Scale * default_global_scale = 0;
  67
  68 LY_DEFINE (ly_set_default_scale, "ly:set-default-scale",
  69            1, 0, 0, (SCM scale),
  70            "Set the global default scale. This determines the tuning of"
  71            " pitches with no accidentals or key signatures.  The first"
  72            " pitch is C. Alterations are calculated relative to this"
  73            " scale.  The number of pitches in this scale determines the"
  74            " number of scale steps that make up an octave.  Usually the"
  75            " 7-note major scale.")
  76 {
  77   LY_ASSERT_SMOB (Scale, scale, 1);
  78
  79   Scale *s = Scale::unsmob (scale);
  80   if (default_global_scale)
  81     default_global_scale->unprotect ();
  82   default_global_scale = s;
  83   s->protect ();
  84
  85   return SCM_UNSPECIFIED;
  86 }
  87
  88 int
  89 Scale::step_count () const
  90 {
  91   return step_tones_.size ();
  92 }
  93
  94 Rational
  95 Scale::tones_at_step (int step, int octave) const
  96 {
  97   int normalized_step = normalize_step (step);
  98
  99   octave += (step - normalized_step) / step_count ();
 100
 101   // There are 6 tones in an octave.
 102   return step_tones_[normalized_step] + Rational (octave*6);
 103 }
 104
 105 Rational
 106 Scale::step_size (int step) const
 107 {
 108   int normalized_step = normalize_step (step);
 109
 110   // Wrap around if we are asked for the final note of the
 111   // scale (6 is the number of tones of the octave above the
 112   // first note).
 113   if (normalized_step + 1 == step_count ())
 114     return Rational(6) - step_tones_[normalized_step];
 115
 116   return step_tones_[normalized_step + 1] - step_tones_[normalized_step];
 117 }
 118
 119 int
 120 Scale::normalize_step (int step) const
 121 {
 122   int ret = step % step_count ();
 123   if (ret < 0)
 124     ret += step_count ();
 125
 126   return ret;
 127 }
 128
 129 int
 130 Scale::print_smob (SCM /* x */,
 131                    SCM port,
 132                    scm_print_state *)
 133 {
 134   scm_puts ("#<Scale>", port);
 135   return 1;
 136 }
 137
 138 SCM
 139 Scale::mark_smob (SCM)
 140 {
 141   return SCM_UNSPECIFIED;
 142 }
 143
 144 Scale::Scale (vector<Rational> const &tones)
 145 {
 146   step_tones_ = tones;
 147
 148   smobify_self ();
 149 }
 150
 151 Scale::Scale (Scale const &src)
 152 {
 153   step_tones_ = src.step_tones_;
 154   smobify_self ();
 155 }
 156
 157
 158 Scale::~Scale ()
 159 {
 160 }
 161
 162 IMPLEMENT_SMOBS (Scale);
 163 IMPLEMENT_DEFAULT_EQUAL_P (Scale);