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Simulators >> AMS Simulators >> programming a decoder in AHDL,Verilog-A
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Message started by vivkr on Sep 1^st, 2005, 2:16am

Title: programming a decoder in AHDL,Verilog-A
Post by vivkr on Sep 1^st, 2005, 2:16am

Hi,

I am trying to create a macromodel for a decoder with 12 bits of control and 4096 outputs.

I was trying to create this using AHDL or Verilog-A but run into trouble with indexing of the signal array. It seems that I can only specify a numeric constant for the signal array. However, this seems to defeat the purpose of using indexed arrays of signals.

I would just like to be able to assert 1 out of the 4096 signals high based on the result of a calculation, and hence my array index element is not constant but a variable.

Has anyone tried such a thing in AHDL or Verilog-A?

Title: Re: programming a decoder in AHDL,Verilog-A
Post by Geoffrey_Coram on Sep 1^st, 2005, 8:45am

It's a little clunky, but this works for me:

Code:

`include "discipline.h"

module dcdr(in,out);
inout in;
inout [0:3] out;
electrical in;
electrical [0:3] out;
real vin;
integer indx;
genvar j;

analog begin
vin = V(in);
if (vin < 1) indx = 0;
else if (vin < 2) indx = 1;
else if (vin < 3) indx = 2;
else indx = 3;

for (j=0; j<3; j=j+1) V(out[j]) <+ 0.0;

`ifdef ORIGINAL
V(out[indx]) <+ 1.0;
`else
for (j=0; j<3; j=j+1) if (j==indx) V(out[j]) <+ 1.0;
`endif

end

endmodule