NAME

       Data::Hexdumper - Make binary data human-readable

SYNOPSIS

           use Data::Hexdumper qw(hexdump);
           print hexdump(
             data           => $data, # what to dump
             # NB number_format is deprecated
             number_format  => 'S',   # display as unsigned 'shorts'
             start_position => 100,   # start at this offset ...
             end_position   => 148    # ... and end at this offset
           );
           print hexdump(
             "abcdefg",
             { output_format => '%4a : %C %S< %L> : %d' }
           );

DESCRIPTION

       "Data::Hexdumper" provides a simple way to format arbitrary binary data into a nice human-
       readable format, somewhat similar to the Unix 'hexdump' utility.

       It gives the programmer a considerable degree of flexibility in how the data is formatted,
       with sensible defaults.  It is envisaged that it will primarily be of use for those
       wrestling alligators in the swamp of binary file formats, which is why it was written in
       the first place.

SUBROUTINES

       The following subroutines are exported by default, although this is deprecated and will be
       removed in some future version.  Please pretend that you need to ask the module to export
       them to you.

       If you do assume that the module will always export them, then you may also assume that
       your code will break at some point after 1 Aug 2012.

   hexdump
       Does everything.  Takes a hash of parameters, one of which is mandatory, the rest having
       sensible defaults if not specified.  Available parameters are:

       data
           A scalar containing the binary data we're interested in.  This is mandatory.

       start_position
           An integer telling us where in "data" to start dumping.  Defaults to the beginning of
           "data".

       end_position
           An integer telling us where in "data" to stop dumping.  Defaults to the end of "data".

       number_format
           This is deprecated.  See 'INCOMPATIBLE CHANGES' below.  If you use this your data will
           be padded with NULLs to be an integer multiple of 16 bytes.  You can expect
           number_format to be removed at some point in 2014 or later.

           A string specifying how to format the data.  It can be any of the following, which you
           will notice have the same meanings as they do to perl's "pack" function:

           C - unsigned char
           S - unsigned 16-bit, native endianness
           v or S< - unsigned 16-bit, little-endian
           n or S> - unsigned 16-bit, big-endian
           L - unsigned 32-bit, native endianness
           V or L< - unsigned 32-bit, little-endian
           N or L> - unsigned 32-bit, big-endian
           Q - unsigned 64-bit, native endianness
           Q< - unsigned 64-bit, little-endian
           Q> - unsigned 64-bit, big-endian

           Note that 64-bit formats are *always* available, even if your perl is only 32-bit.
           Similarly, using < and > on the S and L formats always works, even if you're using a
           pre 5.10.0 perl.  That's because this code doesn't use "pack()".

       output_format
           This is an alternative and much more flexible (but more complex) method of specifying
           the output format.  Instead of specifying a single format for all your output, you can
           specify formats like:

             %4a : %C %S %L> %Q : %d

           which will, on each line, display first the address (consisting of '0x' and 4
           hexadecimal digits, zero-padded if necessary), then a space, then a colon, then a
           single byte of data, then a space, then an unsigned 16-bit value in native endianness,
           then a space, then an unsigned 32-bit big-endian value, ... then a colon, a space,
           then the characters representing your 15 byte record.

           You can use exactly the same characters and character sequences as are specified above
           for number_format, plus 'a' for the address, and 'd' for the data.  To output a
           literal % character, use %% as is normal with formats - see sprintf for details.  To
           output a literal < or > character where it may be confused with any of the
           {S,L,Q}{<,>} sequences, use %< or %>.  So, for example, to output a 16-bit value in
           native endianness followed by <, use %S%<.

           %a takes an optional base-ten number between the % and the a signifying the number of
           hexadecimal digits.  This defaults to 4.

           %{C,S,L,Q} also take an optional base-ten number between the % and the letter,
           signifying the number of repeats.  These will be separated by spaces in the output.
           So '%4C' is equivalent to '%C %C %C %C'.

           Anything else will get printed literally.  This format will be repeated for as many
           lines as necessary.  If the amount of data isn't enough to completely fill the last
           line, it will be padded with NULL bytes.

           To specify both number_format and output_format is a fatal error.

           If neither are given, output_format defaults to:

             '  %4a : %16C : %d'

           which is equivalent to the old-style:

             number_format => 'C'

       suppress_warnings
           Make this true if you want to suppress any warnings - such as that your data may have
           been padded with NULLs if it didn't exactly fit into an integer number of words, or if
           you do something that is deprecated.

       space_as_space
           Make this true if you want spaces (ASCII character 0x20) to be printed as spaces
           Otherwise, spaces will be printed as full stops / periods (ASCII 0x2E).

       Alternatively, you can supply the parameters as a scalar chunk of data followed by an
       optional hashref of the other options:

           $results = hexdump($string);
           $results = hexdump(
             $string,
             { start_position => 100, end_position   => 148 }
           );

SEE ALSO

       Data::Dumper

       Data::HexDump if your needs are simple

       perldoc -f unpack

       perldoc -f pack

INCOMPATIBLE CHANGES

       'number_format' is now implemented in terms of 'output_format'.  Your data will be padded
       to a multiple of 16 bytes.  Previously-silent code may now emit warnings.

       The mappings are:

         'C'  => '  %4a : %C %C %C %C %C %C %C %C %C %C %C %C %C %C %C %C : %d'
         'S'  => '  %4a : %S %S %S %S %S %S %S %S         : %d'
         'S<' => '  %4a : %S< %S< %S< %S< %S< %S< %S< %S<         : %d'
         'S>' => '  %4a : %S> %S> %S> %S> %S> %S> %S> %S>         : %d'
         'L'  => '  %4a : %L %L %L %L             : %d'
         'L<' => '  %4a : %L< %L< %L< %L<             : %d'
         'L>' => '  %4a : %L> %L> %L> %L>             : %d'
         'Q'  => '  %4a : %Q %Q               : %d'
         'Q<' => '  %4a : %Q< %Q<               : %d'
         'Q>' => '  %4a : %Q> %Q>               : %d'

       and of course:

         'V' => 'L<'
         'N' => 'L>'
         'v' => 'S<'
         'n' => 'S>'

BUGS/LIMITATIONS

       Behaviour of %a is not defined if your file is too big.

       Behaviour of %NNa is not defined if NN is too big for your sprintf implementation to
       handle 0x%0${NN}X.

FEEDBACK

       I welcome constructive criticism and bug reports.  Please report bugs either by email or
       via RT:
         <http://rt.cpan.org/Public/Dist/Display.html?Name=Data-Hexdumper>

       The best bug reports contain a test file that fails with the current code, and will pass
       once it has been fixed.  The code repository is on Github:
         <git://github.com/DrHyde/perl-modules-Data-Hexdumper.git>

AUTHOR, COPYRIGHT and LICENCE

       Copyright 2001 - 2012 David Cantrell <david@cantrell.org.uk>

       This software is free-as-in-speech software, and may be used, distributed, and modified
       under the terms of either the GNU General Public Licence version 2 or the Artistic
       Licence.  It's up to you which one you use.  The full text of the licences can be found in
       the files GPL2.txt and ARTISTIC.txt, respectively.

CONSPIRACY

       This module is also free-as-in-mason software.

THANKS TO ...

       MHX, for reporting a bug when dumping a single byte of data

       Stefan Siegl, for reporting a bug when dumping an ASCII 0

       Steffen Winkler, for inspiring me to use proper output formats