lily/misc.cc

   1 /*
   2   This file is part of LilyPond, the GNU music typesetter.
   3
   4   Copyright (C) 1997--2011 Han-Wen Nienhuys <hanwen@xs4all.nl>
   5   Jan Nieuwenhuizen <janneke@gnu.org>
   6
   7   LilyPond is free software: you can redistribute it and/or modify
   8   it under the terms of the GNU General Public License as published by
   9   the Free Software Foundation, either version 3 of the License, or
  10   (at your option) any later version.
  11
  12   LilyPond is distributed in the hope that it will be useful,
  13   but WITHOUT ANY WARRANTY; without even the implied warranty of
  14   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15   GNU General Public License for more details.
  16
  17   You should have received a copy of the GNU General Public License
  18   along with LilyPond.  If not, see <http://www.gnu.org/licenses/>.
  19 */
  20
  21
  22 #include "misc.hh"
  23 #include "warn.hh"
  24
  25 /*
  26   Return the 2-log, rounded down
  27 */
  28 int
  29 intlog2 (int d)
  30 {
  31   assert (d);
  32   int i = 0;
  33   while ((d != 1))
  34     {
  35       d /= 2;
  36       i++;
  37     }
  38
  39   assert (! (d / 2));
  40   return i;
  41 }
  42
  43 double
  44 log_2 (double x)
  45 {
  46   return log (x) / log (2.0);
  47 }
  48
  49 Real
  50 directed_round (Real f, Direction d)
  51 {
  52   if (d < 0)
  53     return floor (f);
  54   else
  55     return ceil (f);
  56 }
  57
  58
  59
  60 /*
  61    0 at threshold,  1 at 0, with 1/x falloff.
  62  */
  63 Real
  64 peak_around (Real epsilon,  Real threshold, Real x)
  65 {
  66   if (x < 0)
  67     return 1.0;
  68   return max (- epsilon * (x - threshold) / ((x + epsilon) * threshold), 0.0);
  69 }
  70
  71 /*
  72   0 at 0,  1 at standard_x, and increasing thereafter.
  73  */
  74 Real
  75 convex_amplifier (Real standard_x, Real increase_factor, Real x)
  76 {
  77   return (exp (increase_factor * x / standard_x) - 1.0) / (exp (increase_factor) - 1.0);
  78 }
  79
  80 string
  81 camel_case_to_lisp_identifier (string in)
  82 {
  83   vector<char> out;
  84
  85   /* don't add '-' before first character */
  86   out.push_back (char (tolower (in[0])));
  87
  88   for (size_t inpos = 1; inpos < in.size (); inpos++)
  89     {
  90       if (isupper (in[inpos]))
  91         out.push_back ('-');
  92       out.push_back ( char(tolower (in[inpos])));
  93     }
  94
  95   string result (&out[0], out.size ());
  96   replace_all (&result, '_', '-');
  97
  98   return result;
  99 }
 100
 101 vsize
 102 utf8_char_len (char current)
 103 {
 104   vsize char_len = 1;
 105
 106   // U+10000 - U+10FFFF
 107   if ((current & 0xF0) == 0xF0)
 108     char_len = 4;
 109   // U+0800 - U+FFFF
 110   else if ((current & 0xE0) == 0xE0)
 111     char_len = 3;
 112   // U+0080 - U+07FF
 113   else if ((current & 0xC0) == 0xC0)
 114     char_len = 2;
 115   else if (current & 0x80)
 116     programming_error ("invalid UTF-8 string");
 117
 118   return char_len;
 119 }