From: Michael Käppler <xmichael-k@web.de>
Date: Sat, 28 Feb 2009 09:20:38 +0000 (+0100)
Subject: This fixes an endless loop in duration.cc:67.
X-Git-Tag: release/2.12.3-1~150
X-Git-Url: https://git.donarmstrong.com/?a=commitdiff_plain;h=1c1b4428ca2e71b62c2c5ed3042e680dd1085926;p=lilypond.git

This fixes an endless loop in duration.cc:67.

The loop occurred when Duration::Duration(Rational r, bool scale) was called
with r.num() >= 2 * r.den(), f.e. the duration of a longa: r.num = 2,
r.den = 1. If k < 0, the left-shifting-operator << returns an undefined value
instead of right-shifting bits. The fix introduces a new function
shift_left() in misc.hh, which behaves different.
(cherry picked from commit 2a2eb61cf2f92967a1c6d5d872db1c906b2c2e73)
---

diff --git a/lily/duration.cc b/lily/duration.cc
index af924bb4b1..0b80b1ce1f 100644
--- a/lily/duration.cc
+++ b/lily/duration.cc
@@ -53,16 +53,16 @@ Duration::Duration (Rational r, bool scale)
       int p = r.num ();
       int q = r.den ();
       int k = intlog2 (q) - intlog2 (p);
-      if ((p << k) < q)
+      if (shift_left(p, k) < q)
 	k++;
 
-      assert ((p << k) >= q && (p << (k-1)) < q);
+      assert (shift_left(p, k) >= q && shift_left(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;
+      p = shift_left(p, k) - q;
       dots_ = 0;
       while ((p *= 2) >= q)
 	{
diff --git a/lily/include/misc.hh b/lily/include/misc.hh
index e33d836381..12392c0cac 100644
--- a/lily/include/misc.hh
+++ b/lily/include/misc.hh
@@ -28,6 +28,13 @@ sign (int i)
   else return 0;
 }
 
+inline int
+shift_left (int value, int shiftamount)
+{
+ if (shiftamount < 0) return (value >> -shiftamount); 
+  else return (value << shiftamount);
+}
+
 inline Real
 linear_interpolate (Real x, Real x1, Real x2, Real y1, Real y2)
 {