[FFmpeg-devel] [PATCH] eval: add bitor and bitand functions
Reimar Döffinger
Reimar.Doeffinger at gmx.de
Thu Mar 14 22:16:39 CET 2013
On Thu, Mar 14, 2013 at 09:34:40PM +0100, Stefano Sabatini wrote:
> On date Wednesday 2013-03-13 22:51:02 +0100, Michael Niedermayer encoded:
> > On Wed, Mar 13, 2013 at 10:36:45PM +0100, Stefano Sabatini wrote:
> > > TODO: bump micro
> > > ---
> > > doc/eval.texi | 8 ++++++++
> > > libavutil/eval.c | 9 ++++++++-
> > > tests/ref/fate/eval | 9 +++++++++
> > > 3 files changed, 25 insertions(+), 1 deletion(-)
> > >
> > > diff --git a/doc/eval.texi b/doc/eval.texi
> > > index 3b7964c..1dca2da 100644
> > > --- a/doc/eval.texi
> > > +++ b/doc/eval.texi
> > > @@ -32,6 +32,14 @@ Compute arcsine of @var{x}.
> > > @item atan(x)
> > > Compute arctangent of @var{x}.
> > >
> > > + at item bitand(x, y)
> > > + at item bitor(x, y)
> > > +Compute bitwise and/or operation on @var{x} and @var{y}.
> > > +
> > > + at var{x} and @var{y} are converted to integers before executing the
> > > +operation. Operation result is undefined if the integer representation
> > > +of @var{x} or @var{y} takes more than 64 bits.
> >
> > double precission floats do not have 64 bit mantissas so this will
> > fail with many 64bit values
>
> Updated with this commented removed. I assume the reader realizes
> that the conversion is potentially lossy.
That is assuming a bit much I think, maybe it would be better to add
something like:
Note that both the conversion to integer and the conversion back to
floating point can lose precision. Beware of unexpected results for large numbers
(usually 2^53 and larger).
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