X-Git-Url: https://git.donarmstrong.com/?a=blobdiff_plain;f=lily%2Fduration.cc;h=755679fd71cf2d84469e69062efd4b7dabd71be9;hb=5b4b0d6e9a197e8f9eb085b7c2ad78b8be3e5cfc;hp=642d7b250ceda79acb2626a7506ffdca698c548e;hpb=eea589c2d7bee6ab38bc611eb205d4c74e2011f7;p=lilypond.git

diff --git a/lily/duration.cc b/lily/duration.cc
index 642d7b250c..755679fd71 100644
--- a/lily/duration.cc
+++ b/lily/duration.cc
@@ -3,9 +3,8 @@
 
   source file of the LilyPond music typesetter
 
-  (c) 1997--2004 Jan Nieuwenhuizen <janneke@gnu.org>
-                 Han-Wen Nienhuys <hanwen@cs.uu.nl>
-
+  (c) 1997--2008 Jan Nieuwenhuizen <janneke@gnu.org>
+  Han-Wen Nienhuys <hanwen@xs4all.nl>
 */
 
 #include "duration.hh"
@@ -35,6 +34,56 @@ Duration::Duration (int log, int d)
   factor_ = Rational (1, 1);
 }
 
+Duration::Duration (Rational r, bool scale)
+{
+  factor_ = Rational (1, 1);
+
+  if (r.num () == 0.0)
+    {
+      durlog_ = 0;
+      dots_ = 0;
+    }
+  else
+    {
+      /* we want to find the integer k for which 2q/p > 2^k >= q/p.
+	 It's simple to check that k' = \floor \log q - \floor \log p
+	 satisfies the left inequality and is within a factor of 2 of
+	 satistying the right one. Therefore either k = k' or k = k'+1 */
+
+      int p = r.num ();
+      int q = r.den ();
+      int k = intlog2 (q) - intlog2 (p);
+      if ((p << k) < q)
+	k++;
+
+      assert ((p << k) >= q && (p << (k-1)) < q);
+
+      /* If we were to write out log (p/q) in base 2, then the position of the
+	 first non-zero bit (ie. k in our notation) would be the durlog
+	 and the number of consecutive 1s after that bit would be the number of
+	 dots */
+      p = (p << k) - q;
+      dots_ = 0;
+      while ((p *= 2) >= q)
+	{
+	  p -= q;
+	  dots_++;
+	}
+
+      /* we only go up to 64th notes */
+      if (k > 6)
+	{
+	  durlog_ = 6;
+	  dots_ = 0;
+	}
+      else
+	durlog_ = k;
+
+      if (scale || k > 6)
+	factor_ = r / get_length ();
+    }
+}
+
 Duration
 Duration::compressed (Rational m) const
 {
@@ -48,7 +97,7 @@ Duration::get_length () const
 {
   Rational mom (1 << abs (durlog_));
 
-  if (durlog_> 0)
+  if (durlog_ > 0)
     mom = Rational (1) / mom;
 
   Rational delta = mom;
@@ -61,13 +110,13 @@ Duration::get_length () const
   return mom * factor_;
 }
 
-String
+string
 Duration::to_string () const
 {
-  String s;
+  string s;
 
-  if (durlog_ < 0  )
-    s = "log = "  + ::to_string (durlog_);
+  if (durlog_ < 0)
+    s = "log = " + ::to_string (durlog_);
   else
     s = ::to_string (1 << durlog_);
 
@@ -77,7 +126,6 @@ Duration::to_string () const
   return s;
 }
 
-
 IMPLEMENT_TYPE_P (Duration, "ly:duration?");
 
 SCM
@@ -90,20 +138,20 @@ IMPLEMENT_SIMPLE_SMOBS (Duration);
 int
 Duration::print_smob (SCM s, SCM port, scm_print_state *)
 {
-  Duration  *r = (Duration *) SCM_CELL_WORD_1 (s);
+  Duration *r = (Duration *) SCM_CELL_WORD_1 (s);
 
   scm_puts ("#<Duration ", port);
-  scm_display (scm_makfrom0str (r->to_string ().to_str0 ()), port);
+  scm_display (ly_string2scm (r->to_string ()), port);
   scm_puts (" >", port);
 
   return 1;
 }
 
 SCM
-Duration::equal_p (SCM a , SCM b)
+Duration::equal_p (SCM a, SCM b)
 {
-  Duration  *p = (Duration *) SCM_CELL_WORD_1 (a);
-  Duration  *q = (Duration *) SCM_CELL_WORD_1 (b);
+  Duration *p = (Duration *) SCM_CELL_WORD_1 (a);
+  Duration *q = (Duration *) SCM_CELL_WORD_1 (b);
 
   bool eq = p->dots_ == q->dots_
     && p->durlog_ == q->durlog_
@@ -112,7 +160,6 @@ Duration::equal_p (SCM a , SCM b)
   return eq ? SCM_BOOL_T : SCM_BOOL_F;
 }
 
-
 int
 Duration::duration_log () const
 {