function in VHDL- make binary

Lothar M. (lkmiller) Moderator (Company: Titel) 2017-11-05 09:37 #5198285

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Noa C. wrote:
> what the function MAKE_BINARY  does in VHDL ?
Simply have a look in the source of the std_logic_arith package:
https://www.csee.umbc.edu/portal/help/VHDL/packages/std_logic_arith_syn.vhd

    -- synopsys synthesis_off
    type tbl_type is array (STD_ULOGIC) of STD_ULOGIC;
    constant tbl_BINARY : tbl_type :=
  ('X', 'X', '0', '1', 'X', 'X', '0', '1', 'X');
    -- synopsys synthesis_on
    function MAKE_BINARY(A : STD_ULOGIC) return STD_ULOGIC is
  -- synopsys built_in SYN_FEED_THRU
    begin
  -- synopsys synthesis_off
      if (IS_X(A)) then
    assert false 
    report "There is an 'U'|'X'|'W'|'Z'|'-' in an arithmetic operand, the result will be 'X'(es)."
    severity warning;
          return ('X');
      end if;
      return tbl_BINARY(A);
  -- synopsys synthesis_on
    end;


> What its puprose?
It takes the input vector and makes a '1' out of a '1' or a 'H", and it 
makes a '0' out of a '0' and a 'L', all the rest will be changed to 'X'.

BTW: I recoomend NOT to use the old Synopsys std_logic_arith libs. Use 
the numeric_std instead. It has all you will need.

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