class AMQ::BitSet

def self.number_of_trailing_ones(num)
  0.upto(BITS_PER_WORD) do |bit|
    return bit if num[bit] == 0
  end
  BITS_PER_WORD
end # number_of_trailing_ones

def check_range(i)
  if i < 0 || i >= @nbits
    raise IndexError.new("Cannot access bit #{i} from a BitSet with #{@nbits} bits")
  end
end # check_range

def clear
  self.init_words(@nbits)
end # clear

def get(i)
  check_range(i)
  w = self.word_index(i)
  (@words[w] & (1 << i % BITS_PER_WORD)) != 0
end # get(i)

def init_words(nbits)
  n      = word_index(nbits-1) + 1
  @words = Array.new(n) { 0 }
end # init_words

def initialize(nbits)
  @nbits = nbits
  self.init_words(nbits)
end # initialize(nbits)

def next_clear_bit()
  @words.each_with_index do |word, i|
    if word == WORD_MASK
      next
    end
    return i * BITS_PER_WORD + BitSet.number_of_trailing_ones(word)
  end
  -1
end # next_clear_bit

def set(i)
  check_range(i)
  w = self.word_index(i)
  result = @words[w] |= (1 << (i % BITS_PER_WORD))
  result
end # set(i)

def to_s
  result = ""
  @words.each do |w|
    result += w.to_s(2).rjust(BITS_PER_WORD,'0') + ":"
  end
  result
end # to_s

def unset(i)
  check_range(i)
  w = self.word_index(i)
  return if w.nil?
  result = @words[w] &= ~(1 << i % BITS_PER_WORD)
  result
end # unset(i)

def word_index(i)
  i >> ADDRESS_BITS_PER_WORD
end # word_index