1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
|
-- Copyright (C) 1996 Morgan Kaufmann Publishers, Inc
-- This file is part of VESTs (Vhdl tESTs).
-- VESTs is free software; you can redistribute it and/or modify it
-- under the terms of the GNU General Public License as published by the
-- Free Software Foundation; either version 2 of the License, or (at
-- your option) any later version.
-- VESTs is distributed in the hope that it will be useful, but WITHOUT
-- ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
-- FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
-- for more details.
-- You should have received a copy of the GNU General Public License
-- along with VESTs; if not, write to the Free Software Foundation,
-- Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
-- ---------------------------------------------------------------------
--
-- $Id: ch_11_fg_11_01.vhd,v 1.2 2001-10-26 16:29:35 paw Exp $
-- $Revision: 1.2 $
--
-- ---------------------------------------------------------------------
entity fg_11_01 is
end entity fg_11_01;
architecture test of fg_11_01 is
-- code from book (in text)
type tri_state_logic is ('0', '1', 'Z');
type tri_state_logic_array is array (integer range <>) of tri_state_logic;
-- end code from book
-- code from book
function resolve_tri_state_logic ( values : in tri_state_logic_array )
return tri_state_logic is
variable result : tri_state_logic := 'Z';
begin
for index in values'range loop
if values(index) /= 'Z' then
result := values(index);
end if;
end loop;
return result;
end function resolve_tri_state_logic;
-- end code from book
-- code from book (in text)
signal s1 : resolve_tri_state_logic tri_state_logic;
subtype resolved_logic is resolve_tri_state_logic tri_state_logic;
signal s2, s3 : resolved_logic;
-- end code from book
begin
source_1 : s1 <= 'Z',
'0' after 10 ns,
'Z' after 20 ns,
'1' after 30 ns,
'Z' after 40 ns,
'1' after 200 ns,
'Z' after 220 ns;
source_2 : s1 <= 'Z',
'0' after 110 ns,
'Z' after 120 ns,
'1' after 130 ns,
'Z' after 140 ns,
'1' after 200 ns,
'0' after 210 ns,
'Z' after 220 ns;
end architecture test;
|
