[Kst] [PATCH] skip off-by-one

[George Staikos]

On Thursday 22 September 2005 13:28, Barth Netterfield wrote:
> The new code is wrong.  It always rounds down, even if you start on a skip
> boundry:
> new_f0 = 2, skip = 2:
> old: ((2-1)/2 + 1) *2 = 2
> new: (2-1)/2*2 = 0
>
> new_f0 = 1, skip = 2
> old: ((1-1)/2 + 1) * 2 = 2;
> new: (1-1)/2*2 = 0;
>
> new_f0 = 0 skip = 1 (eg, more than 1 spf, want only 1 spf)
> old: (0-1)/1+1) * 1= 0
> new: (0-1)/1 * 1 = -1
>
> The new code rounds up to the next skip boundry.  The only trouble with
> this might come if new_f0 between the last skip boundry and the end of the
> file.
>
> Check the nf calculations...

  Of course you're right.  The bug is elsewhere.  I'm trying to track it down, 
but I just finally found the infamous random crash with threads.  This is 
probably the one Matt saw too.  kdDebug() is not threadsafe!!  I'm going to 
have to fix it before I finish tracking down this skip bug.  it's impossible 
to debug right now.  I'll probably have to import our own fork of kdDebug and 
then make a patch for KDE 3.5.  I recommended a redesign of kdebug for 4.0.

-- 
George Staikos
KDE Developer				http://www.kde.org/
Staikos Computing Services Inc.		http://www.staikos.net/