Someone

alias xorb {
  var %s = $iif($bvar($1,0) < $bvar($2,0),$1,$2),%m = $remtok($1-2,%s,32),%l = $bvar(%s,0),%o = $bvar(%m,0)
  while (%l) {
    bset $3 %o $xor($bvar(%s,%l),$bvar(%m,%o))
    dec %o
    dec %l
  }
  bcopy $3 1 %m 1 %o
}