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
90
|
-------------------------------------------------------------------------------
-- Module : mux2to1
-------------------------------------------------------------------------------
-- Author : Johann Faerber
-- Company : University of Applied Sciences Augsburg
-------------------------------------------------------------------------------
-- Description: 2-to-1 multiplexer
-- function modelled as structure of basic logic gates
-------------------------------------------------------------------------------
-- Revisions : see end of file
-------------------------------------------------------------------------------
LIBRARY IEEE;
USE IEEE.std_logic_1164.ALL;
ENTITY mux2to1 IS
PORT (a_i : IN std_ulogic; -- data input a
b_i : IN std_ulogic; -- data input b
sel_i : IN std_ulogic; -- select which input is connected to y
-- sel = '1': a -> y
-- sel = '0': b -> y
y_o : OUT std_ulogic -- data output y
);
END mux2to1;
ARCHITECTURE structure OF mux2to1 IS
COMPONENT invgate
PORT (
a_i : IN std_ulogic;
y_o : OUT std_ulogic);
END COMPONENT;
COMPONENT and2gate
PORT (
a_i : IN std_ulogic;
b_i : IN std_ulogic;
y_o : OUT std_ulogic);
END COMPONENT;
COMPONENT or2gate
PORT (
a_i : IN std_ulogic;
b_i : IN std_ulogic;
y_o : OUT std_ulogic);
END COMPONENT;
SIGNAL p0, p1 : std_ulogic;
SIGNAL p2 : std_ulogic;
BEGIN
inv_gate_1 : invgate
PORT MAP (
a_i => sel_i,
y_o => p2);
and2_gate_1 : and2gate
PORT MAP (
a_i => a_i,
b_i => sel_i,
y_o => p0);
and2_gate_2 : and2gate
PORT MAP (
a_i => b_i,
b_i => p2,
y_o => p1);
or2_gate_1 : or2gate
PORT MAP (
a_i => p0,
b_i => p1,
y_o => y_o);
-- inv_gate_1 : invgate PORT MAP (sel_i, p2);
-- and2_gate_1 : and2gate PORT MAP (a_i, sel_i, p0);
-- and2_gate_2 : and2gate PORT MAP (b_i, p2, p1);
-- or2_gate_1 : or2gate PORT MAP (p0, p1, y_o);
END structure;
-------------------------------------------------------------------------------
-- Revisions:
-- ----------
-- $Id:$
-------------------------------------------------------------------------------
|
