Re: Rounding off ? (updated)

I can't reproduce that here, I'm getting the output:

3243BCFE21EF4468
EF453276BDBDE566
2342ED65876AB55F
[download]

Maybe you're on a 32-bit build of Perl?* Also, what version of Perl are you on? Maybe you could post the output of perl -V here.

Anyway, yes, it's possible you're seeing some rounding effects, although I'm not sure exactly what since I can't see it here. printf is probably numifying the object into a regular Perl number, which may not be large enough to hold the value*. However, Math::BigInt provides the as_hex method:

use warnings;
use strict;
use Math::BigInt;

my @CRCTable = (
    Math::BigInt->new("0x3243bcfe21ef4468"),
    Math::BigInt->new("0xef453276bdbde566"),
    Math::BigInt->new("0x2342ed65876ab55f"),
);

for my $crc (@CRCTable) {
    print $crc->as_hex, "\n";
}

__END__

0x3243bcfe21ef4468
0xef453276bdbde566
0x2342ed65876ab55f
[download]

* Update: Based on the replies I have to revise my guess: maybe you are doing some operations on the BitInts that you haven't shown here? Are you certain that the output you've posted here is exactly what you get when you run the exact code you've posted here? If yes, maybe there's something different about your build of Perl. In addition to the output of perl -V, please show the output of perl -MMath::BigInt -le 'print $Math::BigInt::VERSION'.

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Re^2: Rounding off ? by Your Mother (Archbishop) on Sep 13, 2018 at 23:03 UTC
FWIW, I get exactly the same output with that code. `This is perl 5, version 18, subversion 2 (v5.18.2) built for darwin-thread-multi-2level.`	[reply] [d/l]
Re^2: Rounding off ? by rizzo (Curate) on Sep 14, 2018 at 02:20 UTC
Maybe you're on a 32-bit build of Perl? On a 32-bit Perl(v5.20.1, i586-linux-thread-multi) i get: FFFFFFFF FFFFFFFF FFFFFFFF while on a 64-bit Perl(v5.28.0, x86_64-linux-thread-multi) I also get: 3243BCFE21EF4468 EF453276BDBDE566 2342ED65876AB55F	[reply]
Re^3: Rounding off ? by haukex (Archbishop) on Sep 14, 2018 at 08:24 UTC
On a 32-bit Perl(v5.20.1, i586-linux-thread-multi) i get: FFFFFFFF FFFFFFFF FFFFFFFF Thanks for checking, I can confirm that result on a 32-bit Perl 5.14 on Windows. Also thanks to Your Mother and hippo for checking.	[reply]
Re^2: Rounding off ? by hippo (Archbishop) on Sep 14, 2018 at 08:08 UTC
Another for getting the same output. `$ perl 1222321.pl 3243BCFE21EF4468 EF453276BDBDE566 2342ED65876AB55F $ perl -v \| head -3 This is perl 5, version 20, subversion 3 (v5.20.3) built for x86_64-li +nux-thread-multi (with 16 registered patches, see perl -V for more detail) $ pmv Math::BigInt 1.9993` [download]	[reply] [d/l]
Re^2: Rounding off ? (updated) by syphilis (Archbishop) on Sep 14, 2018 at 12:56 UTC
In addition to the output of perl -V, please show the output of perl -MMath::BigInt -le 'print $Math::BigInt::VERSION' Yes, I think we really need this information from Zomalaja before we can make any sense of it. It seems very odd (to me, at least) that printf's %X formatting should be outputting 54-bit precision values. Cheers, Rob	[reply]
Re^2: Rounding off ? (updated) by Zomalaja (Initiate) on Sep 14, 2018 at 14:52 UTC
`perl -v : This is perl, v5.10.1 (*) built for amd64-freebsd perl -MMath::BigInt -le 'print $Math::BigInt::VERSION' : 1.89 Fix was: printf("%08X%08X\n",$CRCTable[$i] >> 32,($CRCTable[$i] & 0xFFFFFFFF));` [download] This is a shell box that I 'rent' so it is unlikely that it will be updated. Thanks to everyone for their replies - Zomalaja	[reply] [d/l]