How to get the length of a formatted string read in using fscanf in SystemVerilog? - system-verilog

Question

I am reading a text file which has string test cases and decode them to process as Verilog test constructs to simulate. The code that I use to read a file is as follows:
integer pntr,file;
string a,b,c,d;
initial
begin
pntr = $fopen(FOO, "r");
end
always
begin
if(!$feof(pntr))
begin
file = $fscanf(pntr, "%s %s %s %s \n", a,b,c,d);
end
else
$fclose(pntr);
I have tried using
integer k;
k = strlen($fscanf(pntr, "%s %s %s %s \n", a,b,c,d));
$display(k);
and the display statement outputs an "x"
I also tried using
$display(file)
but this also gives me x as the display output. The above code is just a representation of my problem, I am using a larger formatted string to read in larger data. Each line of my testcase may have different size. I have initialized the format to the maximum number of string literals that my testcase can have. I wanted to ask if there is a way to get the length of each line that I read or number of string literals that fscanf read ?
Note: I am using Cadence tools for this task.
Input file looks like
read reg_loc1
write regloc2 2.5V regloc3 20mA
read regloc3 regloc5 regloc7

Answer 1

It's hard to debug your code when you have lots of typos and incomplete code. And you also have a race condition in that pntr may not have been assigned from $fopen if the always block executes before the initial block.
But in any case, the problem with using $fscanf and the %s format is that a newline gets treated as whitespace. It's better to use $fgets to read a line at a time, and the use $sscanf to parse the line:
module top;
integer pntr,file;
string a,b,c,d, line;
initial begin
pntr = $fopen("FOO", "r");
while(!$feof(pntr))
if ((file = $fgets(line,pntr)!=0)) begin
$write("%d line: ", file, line);
file = $sscanf(line, "%s %s %s %s \n", a,b,c,d);
$display(file,,a,b,,c,,d);
end
$fclose(pntr);
end
endmodule