gistfile1.pl

sub attr_unpack {
	shift if ref($_[0]); # called in object context, ditch the object
	my $data = shift;
	my ($num, $fg, $bg, $bo, $fa, $st, $ul, $bl, $rv);

	$num = unpack ('S', $data);

	($fg, $bg, $bo, $fa, $st, $ul, $bl, $rv) = (
	  $num & 7,
	  ($num >> 4) & 7,
	  ($num >> 8) & 1,
	  ($num >> 9) & 1,
	  ($num >> 10) & 1,
	  ($num >> 11) & 1,
	  ($num >> 12) & 1,
	  ($num >> 13) & 1
	);

	return ($fg, $bg, $bo, $fa, $st, $ul, $bl, $rv);
}

gistfile2.c

SV*
attr_unpack(self, sv_buf)
    SV *self
    SV *sv_buf
  PPCODE:
    char *buf = SvPV_nolen(sv_buf);

    EXTEND(SP, 8);

    mPUSHs( newSViv(  buf[0] & 7      ) );
    mPUSHs( newSViv( (buf[0] >> 4) & 7) );
    mPUSHs( newSViv(  buf[1]       & 1) );
    mPUSHs( newSViv( (buf[1] >> 1) & 1) );
    mPUSHs( newSViv( (buf[1] >> 2) & 1) );
    mPUSHs( newSViv( (buf[1] >> 3) & 1) );
    mPUSHs( newSViv( (buf[1] >> 4) & 1) );
    mPUSHs( newSViv( (buf[1] >> 5) & 1) );