source file of the LilyPond music typesetter
- (c) 1997--2005 Jan Nieuwenhuizen <janneke@gnu.org>
- Han-Wen Nienhuys <hanwen@cs.uu.nl>
-
+ (c) 1997--2007 Jan Nieuwenhuizen <janneke@gnu.org>
+ Han-Wen Nienhuys <hanwen@xs4all.nl>
*/
#include "duration.hh"
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
{
{
Rational mom (1 << abs (durlog_));
- if (durlog_> 0)
+ if (durlog_ > 0)
mom = Rational (1) / mom;
Rational delta = mom;
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_);
return s;
}
-
IMPLEMENT_TYPE_P (Duration, "ly:duration?");
SCM
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_
return eq ? SCM_BOOL_T : SCM_BOOL_F;
}
-
int
Duration::duration_log () const
{