code: def _FloatDecoder():
    
  
    local_unpack = struct.unpack
  
    def InnerDecode(buffer, pos):
      # We expect a 32-bit value in little-endian byte order.  Bit 1 is the sign
      # bit, bits 2-9 represent the exponent, and bits 10-32 are the significand.
      new_pos = pos + 4
      float_bytes = buffer[pos:new_pos]
  
      # If this value has all its exponent bits set, then it's non-finite.
      # In Python 2.4, struct.unpack will convert it to a finite 64-bit value.
      # To avoid that, we parse it specially.
      if (float_bytes[3:4] in b'\x7F\xFF' and float_bytes[2:3] >= b'\x80'):
        # If at least one significand bit is set...
        if float_bytes[0:3] != b'\x00\x00\x80':
          return (_NAN, new_pos)
        # If sign bit is set...
        if float_bytes[3:4] == b'\xFF':
          return (_NEG_INF, new_pos)
        return (_POS_INF, new_pos)
  
      # Note that we expect someone up-stack to catch struct.error and convert
      # it to _DecodeError -- this way we don't have to set up exception-
      # handling blocks every time we parse one value.
      result = local_unpack('<f', float_bytes)[0]
      return (result, new_pos)
    return _SimpleDecoder(wire_format.WIRETYPE_FIXED32, InnerDecode)
docs: Returns a decoder for a float field.
  
    This code works around a bug in struct.unpack for non-finite 32-bit
    floating-point values.