my $bytes_per_value = 5;

# to simulate the byte stream  using 40bit = 5 * 8bit;
my $value = 0xf_dead_beef_4;
my $bin_value = substr (pack ('Q', $value), 0, $bytes_per_value);
my $buffer = $bin_value x 4

my $nbytes = length ($buffer);

my $fmt = sprintf "(b%d)*", $bytes_per_value << 3;
my @stream_data = unpack ($fmt, substr ($buffer, 0, $nbytes));
my @values = map { oct '0b'.reverse ($_)} @stream_data;
foreach my $v (@values) {
   printf "0x%x\n", $v;
}