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 #include "warn.hh"
  13
  14 /*
  15   Return the 2-log, rounded down
  16 */
  17 int
  18 intlog2 (int d)
  19 {
  20   assert (d);
  21   int i = 0;
  22   while ((d != 1))
  23     {
  24       d /= 2;
  25       i++;
  26     }
  27
  28   assert (! (d / 2));
  29   return i;
  30 }
  31
  32 double
  33 log_2 (double x)
  34 {
  35   return log (x) / log (2.0);
  36 }
  37
  38 Real
  39 directed_round (Real f, Direction d)
  40 {
  41   if (d < 0)
  42     return floor (f);
  43   else
  44     return ceil (f);
  45 }
  46
  47
  48
  49 /*
  50    0 at threshold,  1 at 0, with 1/x falloff.
  51  */
  52 Real
  53 peak_around (Real epsilon,  Real threshold, Real x)
  54 {
  55   if (x < 0)
  56     return 1.0;
  57   return max (- epsilon * (x - threshold) / ((x + epsilon) * threshold), 0.0);
  58 }
  59
  60 /*
  61   0 at 0,  1 at standard_x, and increasing thereafter.
  62  */
  63 Real
  64 convex_amplifier (Real standard_x, Real increase_factor, Real x)
  65 {
  66   return (exp (increase_factor * x / standard_x) - 1.0) / (exp (increase_factor) - 1.0);
  67 }
  68
  69 string
  70 camel_case_to_lisp_identifier (string in)
  71 {
  72   vector<char> out;
  73
  74   /* don't add '-' before first character */
  75   out.push_back (char (tolower (in[0])));
  76
  77   for (size_t inpos = 1; inpos < in.size (); inpos++)
  78     {
  79       if (isupper (in[inpos]))
  80         out.push_back ('-');
  81       out.push_back ( char(tolower (in[inpos])));
  82     }
  83
  84   string result (&out[0], out.size ());
  85   replace_all (&result, '_', '-');
  86
  87   return result;
  88 }
  89
  90 vsize
  91 utf8_char_len (char current)
  92 {
  93   vsize char_len = 1;
  94
  95   // U+10000 - U+10FFFF
  96   if ((current & 0xF0) == 0xF0)
  97     char_len = 4;
  98   // U+0800 - U+FFFF
  99   else if ((current & 0xE0) == 0xE0)
 100     char_len = 3;
 101   // U+0080 - U+07FF
 102   else if ((current & 0xC0) == 0xC0)
 103     char_len = 2;
 104   else if (current & 0x80)
 105     programming_error ("invalid UTF-8 string");
 106
 107   return char_len;
 108 }