in reply to Re^7:ECC computation
in thread ECC computation

Thanks, it is quite fast, but doesn't seem to match parity I have. My specification was perhaps ambiguous.

I tried online parity calculator from here.

For example, I entered my hex data 7EA0F6A0 and clicked 'use extra parity bit'. Then the hamming code it generated is 0111111 (The CGI code for this is such that it puts the code in LSB bits for some reason).

With the Perl code, I see ECC as 0110110.

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Re^9: ECC computation
by choroba (Cardinal) on Jan 07, 2020 at 09:47 UTC
    OK, so just reverse all the masks and store the bits in reverse order into each @r: 
    my @masks = qw( 01010110101010101010110101011011
                10011011001100110011011001101101
                11100011110000111100011110001110
                00000011111111000000011111110000
                00000011111111111111100000000000
                11111100000000000000000000000000
                11111111111111111111111111111111 );
sub ecc {
    my ($hex) = @_;
    my $d = unpack 'B32', pack 'H8', $hex;
    my @r;
    unshift @r, unpack '%1B*', $_ & $d for @masks;
    $r[0] = unpack '%1B*', $r[0] . join "", @r[ 1 .. $#r ];
    return join "", @r
}

    [download]
    map{substr$_->[0],$_->[1]||0,1}[\*||{},3],[[]],[ref qr-1,-,-1],[{}],[sub{}^*ARGV,3]
[reply]
[d/l]
[select]
      Thanks a bunch! This is working very efficiently!
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