Bug #39714 for Bit-Vector: Bug - Must allocate extra space to receive valid data in conversion from hex to decimal

Tue Sep 30 14:00:46 2008 Stephen.Gray [...] maxim-ic.com - Ticket created

Subject:	Bug - Must allocate extra space to receive valid data in conversion from hex to decimal
Date:	Tue, 30 Sep 2008 12:57:54 -0500
To:	"bug-Bit-Vector [...] rt.cpan.org" <bug-Bit-Vector [...] rt.cpan.org>
From:	Stephen P Gray <Stephen.Gray [...] maxim-ic.com>

When declaring a new_Hex item one must pad at least one extra bit in the size field or when converting to decimal the value returned is invalid. Show quoted text

>>> Code >>>

my $hex = '966104526fe7d8baac32d27124a467b8'; my $vec = Bit::Vector->new_Hex(128, $hex); print "128 bits - $hex => " . $vec->to_Dec() . "\n"; my $vec2 = Bit::Vector->new_Hex(129, $hex); print "129 bits - $hex => " . $vec2->to_Dec() . "\n"; <<< End Code <<< Show quoted text

>>> Output >>>

128 bits - 966104526fe7d8baac32d27124a467b8 => -140394427096942342042315520958275491912 129 bits - 966104526fe7d8baac32d27124a467b8 => 199887939823996121421059086473492719544 <<< End Output <<< OS: SunOS caddo 5.8 Generic_117350-36 sun4u sparc Perl::Version: 5.8.1 Bit::Vector::Version: 6.4 Stephen P. Gray Maxim Integrated Products Test Engineer I (972) 371-4631 Stephen.Gray@maxim-ic.com

Mon Jul 27 07:46:35 2009 STBEY [...] cpan.org - Correspondence added 15 min

On Tue Sep 30 14:00:46 2008, Stephen.Gray@maxim-ic.com wrote: Show quoted text

> When declaring a new_Hex item one must pad at least one extra bit in > the size field or when converting to decimal the value returned is > invalid. >

> >>> Code >>>

> my $hex = '966104526fe7d8baac32d27124a467b8'; > my $vec = Bit::Vector->new_Hex(128, $hex); > print "128 bits - $hex => " . $vec->to_Dec() . "\n"; > > my $vec2 = Bit::Vector->new_Hex(129, $hex); > print "129 bits - $hex => " . $vec2->to_Dec() . "\n"; > > <<< End Code <<< >

> >>> Output >>>

> 128 bits - 966104526fe7d8baac32d27124a467b8 => > -140394427096942342042315520958275491912 > 129 bits - 966104526fe7d8baac32d27124a467b8 => > 199887939823996121421059086473492719544 > <<< End Output <<< > > OS: SunOS caddo 5.8 Generic_117350-36 sun4u sparc > Perl::Version: 5.8.1 > Bit::Vector::Version: 6.4 > > Stephen P. Gray > Maxim Integrated Products > Test Engineer I > (972) 371-4631 > Stephen.Gray@maxim-ic.com

This is the intended and documented behaviour, due to the internal two's complement representation of numbers, the switching between unsigned and signed semantics and the lack of "sign extension" in the from/to_Hex methods (the "Copy" method does that, however - see the manual!). CODE: #!perl -w use Bit::Vector; my $hex = '966104526fe7d8baac32d27124a467b8'; my $vec = Bit::Vector->new_Hex(128, $hex); print "128 bits - $hex => " . $vec->to_Dec() . " " . $vec->to_Hex() . "\n"; my $vec2 = Bit::Vector->new_Hex(129, $hex); print "129 bits - $hex => " . $vec2->to_Dec() . " " . $vec->to_Hex() . "\n"; $vec2->MSB(1); print "129 bits - $hex => " . $vec2->to_Dec() . " " . $vec->to_Hex() . "\n"; OUTPUT: 128 bits - 966104526fe7d8baac32d27124a467b8 => -140394427096942342042315520958275491912 966104526FE7D8BAAC32D27124A467B8 129 bits - 966104526fe7d8baac32d27124a467b8 => 199887939823996121421059086473492719544 966104526FE7D8BAAC32D27124A467B8 129 bits - 966104526fe7d8baac32d27124a467b8 => -140394427096942342042315520958275491912 966104526FE7D8BAAC32D27124A467B8

Mon Jul 27 07:46:36 2009 The RT System itself - Status changed from 'new' to 'open'

Mon Jul 27 07:46:37 2009 STBEY [...] cpan.org - Status changed from 'open' to 'rejected'

Mon Jul 27 07:49:46 2009 STBEY [...] cpan.org - Correspondence added

Sorry, there was a slight glitch in the code and output: CODE: #!perl -w use Bit::Vector; my $hex = '966104526fe7d8baac32d27124a467b8'; my $vec = Bit::Vector->new_Hex(128, $hex); print "128 bits - $hex => " . $vec->to_Dec() . " " . $vec->to_Hex() . "\n"; my $vec2 = Bit::Vector->new_Hex(129, $hex); print "129 bits - $hex => " . $vec2->to_Dec() . " " . $vec2->to_Hex() . "\n"; $vec2->MSB(1); print "129 bits - $hex => " . $vec2->to_Dec() . " " . $vec2->to_Hex() . "\n"; OUTPUT: 128 bits - 966104526fe7d8baac32d27124a467b8 => -140394427096942342042315520958275491912 966104526FE7D8BAAC32D27124A467B8 129 bits - 966104526fe7d8baac32d27124a467b8 => 199887939823996121421059086473492719544 0966104526FE7D8BAAC32D27124A467B8 129 bits - 966104526fe7d8baac32d27124a467b8 => -140394427096942342042315520958275491912 1966104526FE7D8BAAC32D27124A467B8

Mon Jul 27 07:49:46 2009 The RT System itself - Status changed from 'rejected' to 'open'

Mon Jul 27 08:54:06 2009 STBEY [...] cpan.org - Correspondence added

Sorry, this bug report is rejected (no bug).

Mon Jul 27 08:54:08 2009 STBEY [...] cpan.org - Status changed from 'open' to 'rejected'