* bit set, clear, test routines
* call bis (bitnum, word)
* call bic (bitnum, word)
* call setbit (bitnum, word, state)
* bis(bic) sets(clears) bitnum in word
* setbit sets bitnum in word to 1 if state is .true.
* bit tests bitnum in word and returns a logical (t/f) value
return((*w
& (1L << (*n
))) != 0);