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
> > +@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.
>From f2772a82779b16982e3bc74176c6ff1011156096 Mon Sep 17 00:00:00 2001
From: Stefano Sabatini <stefa...@gmail.com>
Date: Mon, 1 Jan 2024 20:32:38 +0100
Subject: [PATCH 1/2] libavutil/eval: introduce UINT64_MAX constant
This might be useful, e.g. when setting the random seed expressed as a
uint64_t value.
---
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..dec009a015 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
+@item UINT64_MAX
+maximum value expressed as an unsigned 64-bits integer, corresponds to
+18446744073709551615 ((2^64)-1)
@end table
Assuming that an expression is considered "true" if it has a non-zero
diff --git a/libavutil/eval.c b/libavutil/eval.c
index dc6b3697bc..93048bff91 100644
--- a/libavutil/eval.c
+++ b/libavutil/eval.c
@@ -100,6 +100,7 @@ static const struct {
{ "PI", M_PI },
{ "PHI", M_PHI },
{ "QP2LAMBDA", FF_QP2LAMBDA },
+ { "UINT64_MAX", UINT64_MAX }
};
double av_strtod(const char *numstr, char **tail)
--
2.34.1
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