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# my @input = ( 0xC1, 0xB3, 0xE0, 0x81, ... );
my @input = do { local $/; unpack "C*", pack "H*", <> =~ s/\s//gr };

# my $input = "\xC1\xB3\xE0\x81...";
my $input = do { local $/; pack "H*", <> =~ s/\s//gr };

(?: [\x00-\x7F]
|   [\xC0-\xDF][\x80-\xBF]
|   [\xE0-\xEF][\x80-\xBF]{2}
|   ...
)

my @bytes = unpack 'C*', $encoded_value;

...
elsif (@bytes == 2) { push @output, (( $bytes[0] & 0x1F ) << 6 ) | ( $
+bytes[0] & 0x3F ); }
elsif (@bytes == 3) { push @output, (( $bytes[0] & 0x0F ) << 12 ) | ((
+ $bytes[0] & 0x3F ) << 6 ) | ( $bytes[0] & 0x3F ); }
...

say join " ", map sprintf("%X", $_), @output;

# Separated by "." instead of spaces.
say sprintf "%vX", pack "W*", @output;