use bit trick to test for power of 2

grosser · Dec 4, 2015 · fd04cb4 · fd04cb4
1 parent 6a256aa
commit fd04cb4
Showing 1 changed file with 1 addition and 1 deletion.
diff --git a/lib/bitfields.rb b/lib/bitfields.rb
@@ -30,7 +30,7 @@ def inherited(klass)
   def self.extract_bits(options)
     bitfields = {}
     options.keys.select{|key| key.is_a?(Numeric) }.each do |bit|
-      raise "#{bit} is not a power of 2 !!" unless bit.to_s(2).scan('1').size == 1
+      raise "#{bit} is not a power of 2 !!" unless bit & (bit - 1) == 0
       bit_name = options.delete(bit).to_sym
       raise DuplicateBitNameError if bitfields.include?(bit_name)
       bitfields[bit_name] = bit