#!/usr/bin/ruby

class Hex2Bin
	attr_accessor :data;
 
	def initialize
		@data = ""
		@invert = false
	end
 
	# store the result of the contained block of code
	# into a buffer
	def block
		temp = @data
		inverted = @invert
		@invert = false;
		@data = ""
		yield
		newdata = @data
		@data = temp
		@invert = inverted;
		return newdata
	end

	# invert the contained block of code
	def invert
		@invert = !@invert;
		yield
		@invert = !@invert;
	end

	# reverse the bytes in the contained
	# block of code
	def reverse_bytes
		temp = block{
			yield
		}
		binary(temp.reverse)
	end
	
	# reverse the bits in the contained 
	# block of code
	def reverse_bits
		reverse_bytes{
			temp = block{
				yield;
			}
			binary(temp.unpack("B*").pack("b*"))
		}
	end
 
	# chunk the buffer specified into blocks of
	# the specified size and then iterate
	# over them
	def each_chunk(data, size)
		(1..(data.length/size.to_f).ceil).each{ |count|
			start = (count - 1)*size
			last = (count)*size - 1;
			if(last >= data.length) then
				last = data.length() -1
			end
			yield(data[start..last])
		}
	end

	# repeat the contained code 
	# the specified number of times
	def repeat( count )
		(1..count).each{ |index| yield(index)}
	end

	# write the specified binary data
	def binary(binary_str)
		if(@invert) then
			binary_str = binary_str.unpack("C*").collect{|x| ~x}.pack("C*")
		end
		@data << binary_str
	end
 
	# convert the specified hex string
	# to binary data
	def hex(hex_str)
		binary( hex_str.gsub(/\s/,'').to_a.pack("H*") )
	end
 
	# write the specified ascii string as
	# ascii data
	def ascii(ascii_string)
		binary( ascii_string )
	end
 
	# write the specified value as a byte
	def byte(value)
		binary([value].pack("C1"))
	end
 
	def get_binding()
		return binding
	end
	
	# shift the data generated by the contained
	# code by the specified number of bits
	# and use the fill bits provided to fill in
	# the left and right edges to byte boundaries
	def shift_right(bits, fill)
		temp = block{
			yield
		}

		fill = [fill].pack("C").unpack("B*")[0];
		data = fill[0, bits] + temp.unpack("B*")[0] + fill[bits, 8-bits]
		binary([data].pack("B*"))
	end
end
context = Hex2Bin.new();
eval(STDIN.read, context.get_binding)
STDOUT.write(context.data);