How to convert 8 bits to 16 bits in VHDL?

Question

I have an input signal from ADC convertor that is 8 bits (std_logic_vector(7 downto 0)). I have to convert them to a 16 bits signal (std_logic_vector(15 d

Answer 1

With the newly released VHDL-2019 standard you can do

larger_vec <= extend(shorter_vec);

where extend is a function defined as follows

function extend(vec : std_logic_vector) return target_vec of std_logic_vector is
  variable result : std_logic_vector(target_vec'length - 1 downto 0) := (others => '0');
begin
  assert vec'length <= target_vec'length report "Cannot extend to shorter vector";
  result(vec'length - 1 downto 0) := vec;
  return result;
end function;

Tool support is still a bit limited but at least one simulator supports this (Riviera-PRO).