[FFmpeg-devel] [PATCH 1/2] libavutil/eval: introduce UINT64_MAX constant

[Stefano Sabatini]

On date Tuesday 2024-01-02 01:10:28 +0100, Michael Niedermayer wrote:
> On Mon, Jan 01, 2024 at 08:38:58PM +0100, Stefano Sabatini wrote:
> > This might be useful, e.g. when setting the random seed expressed as a
> > uint64_t.
> > ---
> >  doc/utils.texi   | 3 +++
> >  libavutil/eval.c | 1 +
> >  2 files changed, 4 insertions(+)
> > 
> > diff --git a/doc/utils.texi b/doc/utils.texi
> > index 0c4f146f4f..ac9b63826e 100644
> > --- a/doc/utils.texi
> > +++ b/doc/utils.texi
> > @@ -1030,6 +1030,9 @@ area of the unit disc, approximately 3.14
> >  exp(1) (Euler's number), approximately 2.718
> >  @item PHI
> >  golden ratio (1+sqrt(5))/2, approximately 1.618
> > + at item UINT64_MAX
> > +maximum value expressed as an unsigned integer, corresponds to
> 
> > +18446744073709551616 ((2^64)-1)
> 
> this doesnt look right
> 2^x is even
> even -1 is odd
> 18446744073709551616 should be a odd number
> 18446744073709551615 looks more likely
> 
> double precission also doesnt like exactly ((2^64)-1) because the mantisse has too few bits
> 
> (U)INT64_MIN should work though exactly in double

Updated.
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