Generic Array

Altera_Forum · ‎10-23-2012

What's the best way to achieve the following statement, when the user_address size depends on a generic value?

generic

(

addr_length: integer;

)

signal addr_enable: std_logic;

signal user_address: std_logic_vector((addr_length - 1) downto 0);

addr_enable <= '0' when (user_address=(others=>'1')) else '1';

Thanks!

Altera_Forum · ‎10-23-2012

best way to read it would be create a constant:


constant ALL_ONES : std_logic_vector((addr_length - 1) downto 0) := (others => '1');
addr_enable <= '0' when (user_address=ALL_ONES) else '1';

Altera_Forum · ‎10-23-2012

or you could use the AND_REDUCE function of the std_logic_misc array:

addr_enable <= '0' when and_reduce(user_address) = '1' else '1';

or the fact that the specified function is just reduced very simply:

addr_enable <= nand_reduce(user_address);

or even simpler in VHDL 2008:

addr_enable <= nand user_address;

Altera_Forum · ‎10-23-2012

Thank you so much!