testsuite/gna/bug073/adder.vhdl


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entity adder is
  -- `i0`, `i1` and the carry-in `ci` are inputs of the adder.
  -- `s` is the sum output, `co` is the carry-out.
  port (i0, i1 : in bit; ci : in bit; s : out bit; co : out bit);
end adder;

architecture rtl of adder is
begin
   --  This full-adder architecture contains two concurrent assignment.
   --  Compute the sum.
   s <= i0 xor i1 xor ci;
   --  Compute the carry.
   co <= (i0 and i1) or (i0 and ci) or (i1 and ci);
end rtl;