Defining a function/procedure in testbench

[madalin1990]

Hi!
I want to write a testbench in VHDL to test writing/reading to/from a register!
I want to use some kind of user defined function to realise the "write to reg X the value Y" function and "read from reg Z the data stored" function.

The problem is I don't know what is best to userocess,function,procedures.Which of the VHDL features do you recommend for my testbench needs?

 

[TrickyDicky]

All three in the right circumstances. The fact you are asking this question shows you probably dont have a great understanding of VHDL. I suggest reading up about functions, procedures and processes from a tutorial.

 

[madalin1990]

I have followed your advice and I read some tutorial about them and I decided procedures were the ones I needed.
But I need a little help once more:how can I write some data to "ModelSim Transcript" to indicate that certain operation were done and to indicate what data was written at the current address?

 

[TrickyDicky]

Two ways:

use the report:

if (something_happened) then report "Something Happened" severity note; --severity level is NOTE, WARNING, ERROR or FAILURE

or use the OUTPUT file declared in textio:

variable l : line;

write(l, string'("Something Happened") );
writeline(OUTPUT, l);

Following this - you can easily write yourself an echo procedure:

procedure echo (arg : in string := "") is
  begin
    std.textio.write(std.textio.output, arg);
  end procedure echo;

 

[madalin1990]

How can i write in the report something like this:
"The data <data_value> was written at the address <address>" where data value and address are procedure's variables.

 

[TrickyDicky]

I suggest you read a textio tutorial..