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https://opencores.org/ocsvn/fast_antilog/fast_antilog/trunk
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/fast_antilog/trunk/AntiLog2.v
0,0 → 1,110
module AntiLog2 |
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/* |
A fast base-2 anti-logarithm function, 10 bits in, 24 bits out. |
Designed and coded by: Michael Dunn, http://www.cantares.on.ca/ |
Executes every cycle, with a latency of 2. |
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The input and output have binary points: In: xxxx.yyyy_yy; Out: xxxx_xxxx_xxxx_xxxx.yyyy_yyyy |
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License: Free to use & modify, but please keep this header intact. |
August 8, 2010, Kitchener, Ontario, Canada |
*/ |
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( |
input [9:0] DIN, |
input clk, |
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output reg [23:0] DOUT |
); |
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// Comprises 2 main blocks: barrel shifter & LUT |
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reg [3:0] barrelshfcnt; |
reg [22:0] LUTout; |
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wire [38:0] tmp1 = ({1'b1, LUTout} << barrelshfcnt); |
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always @(posedge clk) |
begin |
barrelshfcnt <= DIN[9:6]; |
DOUT <= tmp1[38:15]; |
end |
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//LUT for one octave of antilog lookup |
// The equation is: output = (2^(input/64)-1) * 2^23 |
// For larger tables, better to generate a separate data file using a program! |
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always @(posedge clk) |
case (DIN[5:0]) |
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0: LUTout <= 0; |
1: LUTout <= 91346; |
2: LUTout <= 183687; |
3: LUTout <= 277033; |
4: LUTout <= 371395; |
5: LUTout <= 466786; |
6: LUTout <= 563215; |
7: LUTout <= 660693; |
8: LUTout <= 759234; |
9: LUTout <= 858847; |
10: LUTout <= 959546; |
11: LUTout <= 1061340; |
12: LUTout <= 1164243; |
13: LUTout <= 1268267; |
14: LUTout <= 1373424; |
15: LUTout <= 1479725; |
16: LUTout <= 1587184; |
17: LUTout <= 1695814; |
18: LUTout <= 1805626; |
19: LUTout <= 1916634; |
20: LUTout <= 2028850; |
21: LUTout <= 2142289; |
22: LUTout <= 2256963; |
23: LUTout <= 2372886; |
24: LUTout <= 2490071; |
25: LUTout <= 2608532; |
26: LUTout <= 2728283; |
27: LUTout <= 2849338; |
28: LUTout <= 2971711; |
29: LUTout <= 3095417; |
30: LUTout <= 3220470; |
31: LUTout <= 3346884; |
32: LUTout <= 3474675; |
33: LUTout <= 3603858; |
34: LUTout <= 3734447; |
35: LUTout <= 3866459; |
36: LUTout <= 3999908; |
37: LUTout <= 4134810; |
38: LUTout <= 4271181; |
39: LUTout <= 4409037; |
40: LUTout <= 4548394; |
41: LUTout <= 4689269; |
42: LUTout <= 4831678; |
43: LUTout <= 4975637; |
44: LUTout <= 5121164; |
45: LUTout <= 5268276; |
46: LUTout <= 5416990; |
47: LUTout <= 5567323; |
48: LUTout <= 5719293; |
49: LUTout <= 5872918; |
50: LUTout <= 6028216; |
51: LUTout <= 6185205; |
52: LUTout <= 6343903; |
53: LUTout <= 6504329; |
54: LUTout <= 6666503; |
55: LUTout <= 6830442; |
56: LUTout <= 6996167; |
57: LUTout <= 7163696; |
58: LUTout <= 7333050; |
59: LUTout <= 7504247; |
60: LUTout <= 7677309; |
61: LUTout <= 7852255; |
62: LUTout <= 8029107; |
63: LUTout <= 8207884; |
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endcase |
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endmodule |