lily/misc.cc

   1 /*
   2   misc.cc -- implement various stuff
   3
   4   source file of the GNU LilyPond music typesetter
   5
   6   (c) 1997--2009 Han-Wen Nienhuys <hanwen@xs4all.nl>
   7   Jan Nieuwenhuizen <janneke@gnu.org>
   8 */
   9
  10
  11 #include "misc.hh"
  12
  13 /*
  14   Return the 2-log, rounded down
  15 */
  16 int
  17 intlog2 (int d)
  18 {
  19   assert (d);
  20   int i = 0;
  21   while ((d != 1))
  22     {
  23       d /= 2;
  24       i++;
  25     }
  26
  27   assert (! (d / 2));
  28   return i;
  29 }
  30
  31 double
  32 log_2 (double x)
  33 {
  34   return log (x) / log (2.0);
  35 }
  36
  37 Real
  38 directed_round (Real f, Direction d)
  39 {
  40   if (d < 0)
  41     return floor (f);
  42   else
  43     return ceil (f);
  44 }
  45
  46
  47
  48 /*
  49    0 at threshold,  1 at 0, with 1/x falloff.
  50  */
  51 Real
  52 peak_around (Real epsilon,  Real threshold, Real x)
  53 {
  54   if (x < 0)
  55     return 1.0;
  56   return max (- epsilon * (x - threshold) / ((x + epsilon) * threshold), 0.0);
  57 }
  58
  59 /*
  60   0 at 0,  1 at standard_x, and increasing thereafter.
  61  */
  62 Real
  63 convex_amplifier (Real standard_x, Real increase_factor, Real x)
  64 {
  65   return (exp (increase_factor * x / standard_x) - 1.0) / (exp (increase_factor) - 1.0);
  66 }
  67
  68 string
  69 camel_case_to_lisp_identifier (string in)
  70 {
  71   vector<char> out;
  72
  73   /* don't add '-' before first character */
  74   out.push_back (char (tolower (in[0])));
  75
  76   for (size_t inpos = 1; inpos < in.size (); inpos++)
  77     {
  78       if (isupper (in[inpos]))
  79         out.push_back ('-');
  80       out.push_back ( char(tolower (in[inpos])));
  81     }
  82
  83   string result (&out[0], out.size ());
  84   replace_all (&result, '_', '-');
  85
  86   return result;
  87 }
  88