VHDL

Guest
can anyone help me and tell me what this program exactly do please?
1 ENTITY EX8 IS
2 GENERIC (n : NATURAL :=4);
3 PORT (clk, rst : IN BIT;
4 in1, in2 : IN BIT_VECTOR (n-1 DOWNTO 0);
5 opt : OUT BIT_VECTOR (n-1 DOWNTO 0));
6 END EX8;
7 ARCHITECTURE behave OF EX8 IS
8 SIGNAL sopt : BIT_VECTOR (n-1 DOWNTO 0);
9 SIGNAL chng : BIT;
10 BEGIN
11 P0: PROCESS (clk, rst)
12 BEGIN
13 IF rst='1' THEN chng<='0';
14 ELSIF clk'EVENT AND clk='1' THEN
15 IF sopt=in2 THEN chng<='1';
16 ELSIF sopt=in1 THEN chng<='0';
17 END IF;
18 END IF;
19 END PROCESS;
20 P1: PROCESS (clk)
21 BEGIN
22 IF clk'EVENT AND clk='1' THEN
23 IF rst='1' THEN sopt<=in2;
24 ELSE
25 IF chng='0' THEN
26 IF sopt/=in2 THEN sopt<=in2;
27 END IF;
28 ELSE
29 IF sopt/=in1 THEN sopt<=in1;
30 END IF;
31 END IF;
32 END IF;
33 END IF;
34 END PROCESS;
35 opt<=sopt;
36 END behave;
 
On 2/22/2014 9:09 AM, yareen.azzam1@gmail.com wrote:
can anyone help me and tell me what this program exactly do please?
1 ENTITY EX8 IS
2 GENERIC (n : NATURAL :=4);
3 PORT (clk, rst : IN BIT;
4 in1, in2 : IN BIT_VECTOR (n-1 DOWNTO 0);
5 opt : OUT BIT_VECTOR (n-1 DOWNTO 0));
6 END EX8;
7 ARCHITECTURE behave OF EX8 IS
8 SIGNAL sopt : BIT_VECTOR (n-1 DOWNTO 0);
9 SIGNAL chng : BIT;
10 BEGIN
11 P0: PROCESS (clk, rst)
12 BEGIN
13 IF rst='1' THEN chng<='0';
14 ELSIF clk'EVENT AND clk='1' THEN
15 IF sopt=in2 THEN chng<='1';
16 ELSIF sopt=in1 THEN chng<='0';
17 END IF;
18 END IF;
19 END PROCESS;
20 P1: PROCESS (clk)
21 BEGIN
22 IF clk'EVENT AND clk='1' THEN
23 IF rst='1' THEN sopt<=in2;
24 ELSE
25 IF chng='0' THEN
26 IF sopt/=in2 THEN sopt<=in2;
27 END IF;
28 ELSE
29 IF sopt/=in1 THEN sopt<=in1;
30 END IF;
31 END IF;
32 END IF;
33 END IF;
34 END PROCESS;
35 opt<=sopt;
36 END behave;
Click to expand...

That program (VHDL, not Verilog) exactly makes my eyes hurt when I try
to decipher it. If you wrote it, it's no surprise you can't figure it
out. If you didn't write it, you should start by making it human
readable (indetentation, commentary, etc). You'll be surprised what
functionality jumps out at you when you do that.

JJS
 
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