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Design Languages >> Verilog-AMS >> Filename as parameter?
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Message started by Christian on Oct 25^th, 2004, 6:41am

Title: Filename as parameter?
Post by Christian on Oct 25^th, 2004, 6:41am

Hi,

in order to track a lengthy simulation I set up a simple VerilogA model that writes its input into file using a timer event. Now I want to add a parameter so that I may use multiple instances of that block each writing to a different file.
However, I looks like VerilogA has no datatype for filenames. My attempt to write
parameter outfile = "foo.dat";
failed.

Any ideas?

Regards,
Chris

Title: Re: Filename as parameter?
Post by Geoffrey_Coram on Oct 28^th, 2004, 5:19am

Verilog-AMS LRM 2.2 adds support for string parameters, which must be declared as such:
parameter string outfile = "foo.dat";

Alas, Accellera has not yet voted on these extensions, so vendors have not implemented them.

The current support for "strings" in Verilog-AMS is the variable type "reg" (see section 2.6 of the current LRM); also, there is a format specifier "%m" that is supposed to return the hierarchical name of the instance. There's an off chance that you can use these, eg,
reg [8*40:1] outfile;
integer fh;
outfile = "%m";
fh = $fopen(outfile);
or
fh = $fopen("%m");
though I somewhat doubt this will work (%m probably only works in $strobe).

You might be able to do something like
parameter integer blocknum=0;
integer fh;
reg [8*40:1] outfile;
outfile = "output_";
outfile[8] = blocknum+48; // 48==ascii offset of "0"
fh = $fopen(outfile);

-Geoffrey

Title: Re: Filename as parameter?
Post by jbdavid on Nov 1^st, 2004, 7:25pm

None the less
this does work in digital, so as long as you stick all the file operations in the digital side (outside the analog block) you can
define the parameter
parameter filename = "myDefaultfile.ext";

initial begin
fileid = $fopen(filename, "w");
$fstrobe(fileid, "header text\n");
end
always @(someevent) $fstrobe(fileid, "data = %d", datavar);

----
if you want to do string processing, I might refer you to a tutorial on Verilog-AMS with some code examples presented at the 2002 BMAS conference. http://www.bmas-conf.org
see the archives for sesson 2 invited tutorial..
Jonathan