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Altera_Forum
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15 years ago

Code from "MIT press.." Problem

Code: ----- Solution 1: in/out=SIGNED ---------- LIBRARY ieee; USE ieee.std_logic_1164.all; USE ieee.std_logic_arith.all; ------------------------------------------ ENTITY adder1 ISPORT ...
Altera_Forum's avatar
Altera_Forum
Icon for Honored Contributor rankHonored Contributor
15 years ago

first, I think you need to add a "use ieee.numeric_std.all;" to be able to use the unsigned and signed types.

Then the + operator only works on vectors with the same length. You should convert a and b to 5-bit vectors before adding them. Something like: 

sum <= resize(a,5) + resize(b,5);

The resize function works with both unsigned and signed vectors.