How to get most significant bits

[qharz]

Hi
How to get 17 oldest bits from variable std_logic_vector (17 + 2*CONSTANT
downto 0)
CONSTANT is changing manually before every compilation.

Thanks

 

[JimLewis]

Hi
How to get 17 oldest bits from variable std_logic_vector (17 + 2*CONSTANT
downto 0)
CONSTANT is changing manually before every compilation.

Thanks

signal V : std_logic_vector (17 + 2*MY_CONST downto 0) ;
signal L, R : std_logic_vector(16 downto 0) ;


-- 17 left most bits:
L <= V(V'left downto V'left - 16) ;

-- 17 right most bits
R <= V(16 downto 0) ;


Not sure what you mean by oldest, so those are my best guesses.

Cheers,
Jim

 

[KJ]

Not sure what you mean by oldest, so those are my best guesses.

The older ones tend to be on the right...

KJ