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Altera_Forum's avatar
Altera_Forum
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13 years ago

Subtraction with numeric_Std doesn't work

Hello What am i doing in wrong in the code below. subtraction doesn't work! I am using numeric_std and the numbers are in twos complement format. // mattgust library ieee; use ieee....
Altera_Forum's avatar
Altera_Forum
Icon for Honored Contributor rankHonored Contributor
13 years ago

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Also notice that your design is all combinatorial. Nothing wrong about that but once you integrate with registers then you may decide to add registers.

Moreover you can reduce adder/subtractor to one adder only by negating the input (negation require invert and add 1, a small adder):

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You mean like this?:

ALU: process(clk)

begin

if rising_edge(clk)

....

end if;

end process;