"Dr.Ruud" schreef:
Some explanation of the tight code follows.
> my $data = join "\n", map {sprintf "%08b", $_}
> map hex, <DATA> =~ /[[:xdigit:]]+/g ;
Let's start at the end:
@r1 = <DATA> =~ /[[:xdigit:]]+/g ;
That creates a list of the sequences of hexadecimal digit characters out
of the line read from <DATA>.
So it results in "qw(31 59 4C 15 53 DD 54 31)", which is a list of
strings.
Maybe "<DATA> =~ /([[:xdigit:]]+)/g" (with brackets) is more efficient
(like when $& and $1 are involved).
The following step:
@r2 = map hex, @r1 ;
transforms this list to "(0x31, 0x59, ... , 0x54, 0x31)", which is a
list of integers.
The next step:
@r3 = map {sprintf "%08b", $_} @r2 ;
transforms this list to "qw(00110001 01011001 ... 01010100 00110001)",
which is a list of strings.
The next step:
my $data = join "\n", @r3 ;
creates a single string from the list, with "\n" as glue. So $data is
"00110001\n01011001\n...\n01010100\n00110001".
> $data =~ s/(?<=.)\z/\n/
> while $data =~ s/(.+?)(.{7}\n.*)/$2$1/ ;
This appends a \n to $data if there is a non-\n character at the end of
$data, and shortens each embedded line to the trailing 7 characters,
moving the surplus from the current line to the end of the next line
(and that all as many times as possible).
To see what goes on, make it:
do{ $data =~ s/(?<=.)\z/\n/; print "$data\n\n" }
while $data =~ s/(.+?)(.{7}\n.*)/$2$1/ ;
--
Affijn, Ruud
"Gewoon is een tijger."
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