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

-- FIGURE 6.17 





-- ENTITY DECLERATION OF AN 2-INPUT NAND :

USE WORK.basic_utilities.ALL;
ENTITY nand2_q IS
  GENERIC (tplh : TIME := 7 NS; tphl : TIME := 5 NS);
  PORT (i1, i2 : IN qit; o1 : OUT qit);
END nand2_q;
--



-- AVERAGE DELAY ARCHITECTURE OF THE 2-INPUT NAND USING 
   2-DIMENSIONAL ARRAY :

ARCHITECTURE average_delay OF nand2_q IS
  CONSTANT qit_nand2_table : qit_2d := (
                             ('1','1','1','1'),
                             ('1','0','0','X'),
                             ('1','0','0','X'),
                             ('1','X','X','X'));
BEGIN
  o1 <= qit_nand2_table (i1, i2) AFTER (tplh + tphl) / 2;
END average_delay;
--