重载操作符的定义一般见于 IEEE 库的哪几个程序包

A、std_logic_arith、std_logic_unsigned、std_logic_signed

B、std_logic_arith、std_logic_unsigned、std_logic_1164

C、std_logic_unsigned、std_logic_1164、std_logic_arith

D、std_logic_1164、std_logic_arith、std_logic_unsigned、std_logic_signed