I have a series of strings containing 0s and 1s where I am counting the orientation of the 0/1 via bitwise operators. I am doing this as follows; 
my $string1 = '01010110111000';
my $string2 = '11101101100010';

my ( $c00, $c01, $c10, $c11 ) = (

    ( $string1 | $string2 )  =~ tr[0][0],      # count 00
    ( ~$string1 & $string2 ) =~ tr[\1][\1],    # count 01
    ( $string1 & ~$string2 ) =~ tr[\1][\1],    # count 10
    ( $string1 & $string2 )  =~ tr[1][1],      # count 11

);

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However, I have large numbers of these strings, and they are much longer than this example code. For storage reasons, they are stored packed as follows: 
my $len = length $unpacked_string;
my $packed_string = pack qq{b$len}, $unpacked_string;

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In my application, prior to the counting above, I unpack the strings as follows: 
my $unpacked_string = unpack qq{b$len}, $packed_string;

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I was wondering if there is a way to do the 0/1 counts directly on the packed version, and could skip the need to unpack into strings.

In reply to Bitwise operators on binary objects by albert

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