Forum Discussion

Altera_Forum's avatar
Altera_Forum
Icon for Honored Contributor rankHonored Contributor
18 years ago

Error 10327: Can't determine definition of operator ""+""

Hello to everybody, could someone tell me what's wrong in the following code? library ieee; use ieee.std_logic_1164.all; use ieee.numeric_std.all; entity round16to12 is ...
Altera_Forum's avatar
Altera_Forum
Icon for Honored Contributor rankHonored Contributor
8 years ago

a and b are std_logic_vectors. You cannot do arithmatic with them

you need to convert them to unsigned or signed types before you can do arithmatic. You probably want to declare them as signed or unsigned in the first place, or you will need a lot of type conversion:

p := std_logic_vector( unsigned('0' & a) + unsigned('0' & b) );

if p, a and b were all declared as unsigned:

a : unsigned(3 downto 0);

type conversions wouldnt be needed:

p := ('0'&a) + ('0'&b);

Btw, why are you using "after" keyword. It is not synthesisable and is for simulation only.