lily/misc.cc

   1 /*
   2   misc.cc -- implement various stuff
   3
   4   source file of the GNU LilyPond music typesetter
   5
   6   (c)  1997--1999 Han-Wen Nienhuys <hanwen@cs.uu.nl>
   7     Jan Nieuwenhuizen <janneke@gnu.org>
   8 */
   9
  10 #include <math.h>
  11
  12 #include "misc.hh"
  13
  14 #ifndef STANDALONE
  15 #include "item.hh"
  16 #endif
  17
  18 int
  19 intlog2(int d) {
  20   int i=0;
  21   while (!(d&1))
  22     {
  23         d/= 2;
  24         i++;
  25     }
  26   assert (!(d/2));
  27   return i;
  28 }
  29
  30 double
  31 log_2(double x) {
  32   return log (x)  /log (2.0);
  33 }
  34
  35 #ifndef STANDALONE
  36 Interval
  37 itemlist_width (const Array<Item*> &its)
  38 {
  39   Interval iv ;
  40   iv.set_empty();
  41
  42   for (int j =0; j < its.size(); j++)
  43     {
  44         iv.unite (its[j]->extent (X_AXIS));
  45
  46     }
  47   return iv;
  48 }
  49
  50 #endif
  51
  52
  53 /*
  54   TODO
  55     group in some Array_*
  56     make more generic / templatise
  57  */
  58 int
  59 get_lower_bound (Array<Real> const& positions, Real x)
  60 {
  61   if (x < positions[0])
  62     return 0;
  63   for (int i = 1; i < positions.size (); i++)
  64     if (x < positions[i])
  65       return i - 1;
  66   return positions.size () - 1;
  67 }
  68
  69 Slice
  70 get_bounds_slice (Array<Real> const& positions, Real x)
  71 {
  72   int l = get_lower_bound (positions, x);
  73   int u = positions.size () - 1 <? l + 1;
  74   if (x < positions[l])
  75     u = l;
  76   return Slice (l, u);
  77 }
  78
  79 Interval
  80 get_bounds_iv (Array<Real> const& positions, Real x)
  81 {
  82   Slice slice = get_bounds_slice (positions, x);
  83   return Interval (positions[slice[SMALLER]], positions[slice[BIGGER]]);
  84 }
  85
  86 // silly name
  87 Interval
  88 quantise_iv (Array<Real> const& positions, Real period, Real x)
  89 {
  90   /*
  91     ugh
  92     assume that
  93       * positions are sorted,
  94       * positions are nonnegative
  95       * period starts at zero
  96    */
  97
  98   int n = (int)(x / period);
  99   Real frac = (x / period - n) * period;
 100   if (frac < 0)
 101     {
 102       frac += period;
 103       n--;
 104     }
 105
 106   Slice slice = get_bounds_slice (positions, frac);
 107   Interval iv(positions[slice[SMALLER]], positions[slice[BIGGER]]);
 108
 109   if (slice[SMALLER] == slice[BIGGER])
 110     {
 111       if (slice[SMALLER] == 0)
 112         iv[SMALLER] = - period + positions.top ();
 113       else
 114         iv[BIGGER] = period + positions[0];
 115     }
 116
 117   iv += period * n;
 118
 119   return iv;
 120 }