Format elements

Every format element in the format string is starting with % like sprintf.

If the given format is shorter defined as needed for the data length the remaining data are displayed in default format. If the given format is longer defined as the data length the output will filled with space and it stops before next repetition.

Data format

It is not very clever to use little-endian formats for tests. There is a fallback to bytes if multibyte formats can not displayed.

 %C  - unsigned char
 %S  - unsigned 16-bit, endian depends on machine
 %S< - unsigned 16-bit, little-endian
 %S> - unsigned 16-bit, big-endian
 %v  - unsigned 16-bit, little-endian
 %n  - unsigned 16-bit, big-endian
 %L  - unsigned 32-bit, endian depends on machine
 %L< - unsigned 32-bit, little-endian
 %L> - unsigned 32-bit, big-endian
 %V  - unsigned 32-bit, little-endian
 %N  - unsigned 32-bit, big-endian
 %Q  - unsigned 64-bit, endian depends on machine
 %Q< - unsigned 64-bit, little-endian
 %Q> - unsigned 64-bit, big-endian

"pack" and "unpack" before Perl v5.10 do not allow "<" and ">" to mark the byte order. This is allowed here for all Perl versions.

"pack" and "unpack" on a 32 bit machine do not allow the "Q" formats. This is allowed here for all machines.

Address format

 %a  - 16 bit address
 %4a - 16 bit address
 %8a - 32 bit address

ASCII format

It can not display all chars. First it must be a printable ASCII char. It can not be anything of space, q{.}, q{'}, q{"} or q{\}. Otherwise q{.} will be printed.

 %d - display ASCII

Repetition

 %*x - repetition endless
 %1x - repetition 1 time
 %2x - repetition 2 times
 ...

Special formats

 %\n - ignore \n

Default format

The default format is:

 "%a : %4C : %d\n"

or fully written as

 "%a : %4C : %d\n%*x"

Complex formats

The %...x allows to write mixed formats e.g.

 Format:
  %a : %N %4C : %d\n%1x%
  %a : %n %2C : %d\n%*x
 Input:
    \0x01\0x23\0x45\0x67\0x89\0xAB\0xCD\0xEF
    \0x01\0x23\0x45\0x67
    \0x89\0xAB\0xCD\0xEF
 Output:
    0000 : 01234567 89 AB CD EF : .#-Eg...
    0008 : 0123 45 67 : .#-E
    000C : 89AB CD EF : g...

subroutine hex_dump

    $string = hex_dump(
        $binary,
        {
            address => $display_start_address,
            format  => $format_string,
        }
    );