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

-- FIGURE 5.15 




--  BASIC UTILITIES PACKAGE DECLERATION :

PACKAGE basic_utilities IS
  TYPE integers IS ARRAY (0 TO 12) OF INTEGER;
  FUNCTION fgl (w, x, gl : BIT) RETURN BIT;
  FUNCTION feq (w, x, eq : BIT) RETURN BIT;
  PROCEDURE bin2int (bin : IN BIT_VECTOR; int : OUT INTEGER);
  PROCEDURE int2bin (int : IN INTEGER;  bin : OUT BIT_VECTOR);
  PROCEDURE apply_data (
    SIGNAL target : OUT BIT_VECTOR (3 DOWNTO 0); 
    CONSTANT values : IN integers;  CONSTANT period : IN TIME); 
END basic_utilities;
--



--  BASIC UTILITIES PACKAGE BODY :

PACKAGE BODY basic_utilities IS

  FUNCTION fgl (w, x, gl : BIT) RETURN BIT IS
  BEGIN
    RETURN  (w AND gl) OR (NOT x  AND  gl) OR (w  AND  NOT x);
  END fgl;

  FUNCTION feq (w, x, eq : BIT) RETURN BIT IS
  BEGIN
    RETURN  (w AND x AND eq) OR (NOT w  AND  NOT x  AND  eq);
  END feq;

  PROCEDURE bin2int (bin : IN BIT_VECTOR; int : OUT INTEGER) IS
    VARIABLE result: INTEGER;
  BEGIN
    result := 0;
    FOR i IN 0 TO (bin'LENGTH - 1) LOOP
      IF bin(i) = '1' THEN
        result := result + 2**i;
      END IF;
    END LOOP;
    int := result;
  END bin2int;
  
  PROCEDURE int2bin (int : IN INTEGER;  bin : OUT BIT_VECTOR) IS
    VARIABLE tmp : INTEGER;
    VARIABLE buf : BIT_VECTOR (bin'RANGE);
  BEGIN
    tmp := int;
    FOR i IN 0 TO (bin'LENGTH - 1) LOOP
      IF (tmp MOD 2  =  1) THEN 
        bin (i) := '1';
      ELSE bin (i) := '0';
      END IF;
      tmp := tmp / 2;
    END LOOP;
  END int2bin;

  PROCEDURE apply_data (
    SIGNAL target : OUT BIT_VECTOR (3 DOWNTO 0); 
    CONSTANT values : IN integers;  CONSTANT period : IN TIME) 
  IS 
    VARIABLE buf : BIT_VECTOR (3 DOWNTO 0);
  BEGIN
    FOR i IN 0 TO 12 LOOP
      int2bin (values(i), buf);
      target <= TRANSPORT buf AFTER i * period;
    END LOOP;
  END apply_data;

END basic_utilities;
--