-- Copyright © 1993 by  McGraw-Hill, Inc. and Zainalabedin Navabi

-- FIGURE 7.21 




-- ENTITY DECLERATION OF 8-to-1 MULTIPLEXER :

USE WORK.basic_utilities.ALL;
ENTITY mux_8_to_1 IS
  PORT (i7, i6, i5, i4, i3, i2, i1, i0 : IN qit;
        s7, s6, s5, s4, s3, s2, s1, s0 : IN qit; z : OUT qit );
END mux_8_to_1;
--



-- IMPLEMENTING THE 8-to-1 MULTIPLEXER USING 8 CONCURRENT ASSIGNMENTS :

ARCHITECTURE multiple_assignments OF mux_8_to_1 IS
  FUNCTION oring ( drivers : qit_vector) RETURN qit IS
    VARIABLE accumulate : qit := '0';
  BEGIN
    FOR i IN drivers'RANGE LOOP
      accumulate := accumulate OR drivers(i);
    END LOOP;
    RETURN accumulate;
  END oring;
  SIGNAL t : oring qit;
BEGIN
  t <= i7 AND s7;
  t <= i6 AND s6;
  t <= i5 AND s5;
  t <= i4 AND s4;
  t <= i3 AND s3;
  t <= i2 AND s2;
  t <= i1 AND s1;
  t <= i0 AND s0;
  z <= t;
END multiple_assignments;