#!/usr/bin/perl
use warnings;
use strict;

my @bits = (
  1, 0, 0, 0, 0, 0, 1, 0,   # A / 0x41 / 0b01000001
  0, 1, 0, 0, 0, 0, 1, 0,   # B / 0x42 / 0b01000010
  1, 1, 0, 0, 1, 0, 1       # incomplete byte
);

my $string = join q(), @bits;
my $incomplete = @bits % 8 || -@bits;             # The || part handles complete bytes.
print pack "b*", substr $string, 0, -$incomplete;

splice @bits, 0, -$incomplete;                    # Remove the processed part.
print "\n@bits\n";