Using select? Statements - 2022.1 English

Vivado Design Suite User Guide: Synthesis (UG901)

Document ID
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2022.1 English

Like the case, the select statement now has a way to deal with explicit don’t care assignments. When using the select? statement, the tool now evaluates explicit don’t care terms, for example:

process(clk) begin

if clk’event and clk=’1’ then

   with my_reg select?

   out1 <= in1 when "11--",

        in2 when "000-",

        in3 when "1111",

        in4 when others;

end if;

end process;

Note:   For this statement to work, the signal in question must be assigned an explicit don’t care.