Verilog file handling

verilog

I tried to open a file ff.txt and write into it some random numbers say seven times. I used EDA playground website for it. Below is the link for that code as well as that code.

http://www.edaplayground.com/x/TCC

When I try to run I get error as

** Warning: (vsim-3533) [FOFIW] – Failed to open file "ff.txt" for writing.

Permission denied. (errno = EACCES) : design.sv(6)

My question is why don't I have access to the file ff.txt?

     module fopenclose();
       integer mcd,number;
       initial begin
         mcd=$fopen("ff.txt");
         repeat(7) begin
         number=$random;
         $fdisplay(mcd,"Number is",number);
       end
         $fclose(mcd);
       end
       initial #2 $display("%d",mcd);
     endmodule

Best Answer

EDA playground most likely does not provide filesystem access. You will probably need to run this in a simulator on your local computer.

Related Solutions

Electronic – Looking for a program that can simulate a Verilog HDL file

http://en.wikipedia.org/wiki/List_of_Verilog_simulators

At the low-cost end:

iverilog is a well-thought-of open-source simulator.
Xilinx have their own simulator - ISIM
Altera provide a simple version of Modelsim

Verilog Netlist and verilog file not justifying each other

The output only depends on enable and in[0], resulting in the following coding optimization:

module test (input in, input enable, output out);
assign out = enable & in;
endmodule

where in is the old in[0], and the output has been changed to a wire type. Normally, a synthesis tool would do that optimization for you, but here it clearly does not. Optimizing your code yourself will make a circuit which is just one gate instead of 3 gates as in your current result.

I drew the schematic of your netlist and there is not enough information to know if it matches the RTL. I would need to know how the MUX4 module maps the inputs based on the select signal. You can see the "??" which represents some combination of in1 and in[0]. But it is not known which combination selects which input, since you didn't attach the MUX4 model.

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