Change the order of bits based on how Redis setbit/getbit stores them

Author: dalibor

lib/bitarray.rb

@@ -13,15 +13,15 @@ def initialize(size, field = nil)
   # Set a bit (1/0)
   def []=(position, value)
     if value == 1
-      @field.setbyte(position >> 3, @field.getbyte(position >> 3) | (1 << (position % 8)))
+      @field.setbyte(position >> 3, @field.getbyte(position >> 3) | (1 << (7 - position % 8)))
     else
-      @field.setbyte(position >> 3, @field.getbyte(position >> 3) ^ (1 << (position % 8)))
+      @field.setbyte(position >> 3, @field.getbyte(position >> 3) ^ (1 << (7 - position % 8)))
     end
   end
 
   # Read a bit (1/0)
   def [](position)
-    (@field.getbyte(position >> 3) & (1 << (position % 8))) > 0 ? 1 : 0
+    (@field.getbyte(position >> 3) & (1 << (7 - position % 8))) > 0 ? 1 : 0
   end
 
   # Iterate over each bit
@@ -31,7 +31,7 @@ def each(&block)
 
   # Returns the field as a string like "0101010100111100," etc.
   def to_s
-    @field.bytes.collect{|ea| ("%08b" % ea).reverse}.join[0, @size]
+    @field.bytes.collect { |ea| ("%08b" % ea) }.join[0, @size]
   end
 
   # Returns the total number of bits that are set

test/test_bitarray.rb

@@ -52,6 +52,12 @@ def test_to_s
     assert_equal "01000111001000001000000000000000010", ba.to_s
   end
 
+  def test_field
+    ba = BitArray.new(35)
+    [1, 5, 6, 7, 10, 16, 33].each{|i|ba[i] = 1}
+    assert_equal "0100011100100000100000000000000001000000", ba.field.unpack('B*')[0]
+  end
+
   def test_total_set
     ba = BitArray.new(10)
     ba[1] = 1