Generic One-Hot Multiplexer

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I am looking for a way to dynamic instantiate a multiplexer of N channels which has a one-hot encoded select. My current hard-coded version for a 3 channel system looks like this:

Both work correctly, but I have not found a synthesize solution to parameterize the mux to make it generic for use across system builds. I have been unsuccessful trying Generate statements or For Loops to handle the One-Hot select case.

Thanks,

Aaron

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Here is a solution with a for loop:

entity combmuxs is
	generic (
		WIDTH_D		:	natural := 4 ;
		SIZE		:	natural := 16
		) ;
	port (
		D		:	in	std_logic_2D( SIZE - 1 downto 0 , WIDTH_D - 1 downto 0) ;
		Sel		:	in	std_logic_vector(SIZE - 1 downto 0) ;
		Q		:	out	std_logic_vector(WIDTH_D - 1 downto 0)  
		) ;
	end combmuxs ;
architecture a of combmuxs is
	function smux3( d : std_logic_2D ; sel : std_logic_vector)
		return	std_logic_vector
		is
			variable r : std_logic_vector( d'high(2) downto 0) ;
		begin
			r:= (others => '0') ;	-- default return if none selected
			for i in 0 to d'high(1) loop
				if (sel(i) = '1') then
					return  to_std_logic_vector( d , i ) ;
				end if ;
			end loop ;
			return r ;
		end function ;
begin
	process( D , Sel )
		begin
			Q <= smux3(D , Sel) ;
		end process ;
end a ;

It is written for a std_logic_2d from the lpm_components package but it is easy to replace this by a 1Dx1D array. I have written it as a function so I could test other approaches, like a recursive version.

I add the supporting function:

	function to_std_logic_vector( source : std_logic_2D ; idx : natural )
		return std_logic_vector
		is
			variable r : std_logic_vector( source'high(2) downto 0) ;
		begin
			for i in  0 to source'high(2) loop
				r(i) := source(idx , i) ;
			end loop ;
			return r ;
		end function ;