//========================================== // Function : Code Gray counter. // Coder : Alex Claros F. // Date : 15/May/2005. //======================================= module GrayCounter #(parameter COUNTER_WIDTH = 4) (output reg [COUNTER_WIDTH-1:0] GrayCount_out, //'Gray' code count output. input wire Enable_in, //Count enable. input wire Clear_in, //Count reset. input wire Clk); /////////Internal connections & variables/////// reg [COUNTER_WIDTH-1:0] BinaryCount; /////////Code/////////////////////// always @ (posedge Clk) if (Clear_in) begin BinaryCount <= {COUNTER_WIDTH{1'b 0}} + 1; //Gray count begins @ '1' with GrayCount_out <= {COUNTER_WIDTH{1'b 0}}; // first 'Enable_in'. end else if (Enable_in) begin BinaryCount <= BinaryCount + 1; GrayCount_out <= {BinaryCount[COUNTER_WIDTH-1], BinaryCount[COUNTER_WIDTH-2:0] ^ BinaryCount[COUNTER_WIDTH-1:1]}; end endmodule CE40/ghdl/about/'>aboutsummaryrefslogtreecommitdiffstats
path: root/testsuite/gna/bug040/sub_221.vhd
blob: 35b461cbdf1a180a84cba7105609eb4a9b216100 (plain) 
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