module BinData::FloatingPoint

def self.create_float_methods(float_class, precision, endian)
  read = create_read_code(precision, endian)
  to_binary_s = create_to_binary_s_code(precision, endian)
  nbytes = (precision == :single) ? 4 : 8
  define_methods(float_class, nbytes, read, to_binary_s)
end

def self.create_read_code(precision, endian)
  if precision == :single
    unpack = (endian == :little) ? 'e' : 'g'
    nbytes = 4
  else # double_precision
    unpack = (endian == :little) ? 'E' : 'G'
    nbytes = 8
  end
  "io.readbytes(#{nbytes}).unpack('#{unpack}').at(0)"
end

def self.create_to_binary_s_code(precision, endian)
  if precision == :single
    pack = (endian == :little) ? 'e' : 'g'
  else # double_precision
    pack = (endian == :little) ? 'E' : 'G'
  end
  "[val].pack('#{pack}')"
end

def self.define_methods(float_class, nbytes, read, to_binary_s)
  float_class.module_eval <<-END
    def _do_num_bytes
      #{nbytes}
    end
    #---------------
    private
    def sensible_default
      0.0
    end
    def value_to_binary_string(val)
      #{to_binary_s}
    end
    def read_and_return_value(io)
      #{read}
    end
  END
end