Explicitly defines a logic vector constant. logic[] __hex(string value); The __hex() function allows explicitly defining logic vector constants using their hexadecimal representation. It is useful in conjunction with type inference and for declaring large constants (larger than 32 bits).

Note that you can initialize vectors of size 32 and less with normal C++ style integral constants (e.g. 15, 0xF or 0b1111).

entity Test
{
	signal auto xxx = __hex("010"), yyy = 0x010;
	signal logic[12] xx2 = __hex("010"), yy2 = 0x010;
}

Generated VHDL code:

	signal xxx : std_logic_vector(11 downto 0) := X"010";
	signal yyy : integer := 16;
	signal xx2 : std_logic_vector(11 downto 0) := X"010";
	signal yy2 : std_logic_vector(11 downto 0) := X"010";