Here's a little something I came up with:

open(FILE, shift) or die $!;
my (@buffer, @bits);
while(!eof(FILE)) {
   if (@buffer == 0) { #if it's empty, fill it
      my $bytes;
      #read 30 bytes at a time
      read(FILE, $bytes, 30); 
      my @ary = map {ord} split("", $bytes);
      foreach my $byte (@ary) {
         push @buffer, split("", unpack("B*", $byte));
      }
    }
    while(@bits < 128) {
       push (@bits, shift(@buffer));
       last if (@buffer == 0);
    }
    #the first couple of reads will not fill the bits array
    next if (@bits < 128); 
    #your processing on @bits goes here
    shift @bits;
}
[download]

Perhaps later, I'll put up a version that does all of the work in binary strings rather than arrays.

thor