It took me a while to realize why you were checking tz < 63. It's because the shift by 64 that might occur below would be a no-op!
1301 action.accept(i++);1302
word &= (WORD_MASK << i);
Can we rewrite to simply flip the one bit via
word &= ~(1L << i);
action.accept(i++);
and then we can simplify the tz handling?
