System Verilog function that takes any number of strings as an argument? - verilog

Question

I want to have a SystemVerilog function that can accept any number of string arguments, this function is essentially a wrapper around the in-built $display as such I want users to be able to call the function in the same way, passing any number of strings into myfunc() as follows:
myfunc(stringVar1, "literalString", stringVar2, stringVarN, intVarToConvertToString);
My current implementation is to just have a single string arg and use the SystemVerilog concatenation operator to concatenate all the strings I wish to pass; e.g.
myfunc({stringVar1, "literalString", stringVar2, stringVarN, intVarToConvertToString});
however when I try to pass in a numeric type like int as a concatenated string, it isn't being converted into a string representation of its value correctly, and the � character is printed in its place. I have also tried to perform an explicit string cast on the non-string types being concatenated but to no avail.
I know that if I got all of the arguments to my function separately I can then just pass them directly to $display which does correctly convert the number types to their string representation to display them. Does anyone know how I would do this in System Verilog?

Answer 1

If you want to convert an integer's value into a string representation, or more specifically, a "string" of ASCII digits, you need to use a formatting function, like $sformatf("%d",intVarToConvertToString) to convert a value to a decimal representation, or you can combine the concatenation and formatting into a single expression.
myfunc($sformat("%s%s%s%d",{stringVar1, "literalString"}, stringVar2, stringVarN, intVarToConvertToString);

Answer 2

The concat operator {} converts its contents in a stream of bits.
There are no variable arguments in verilog/system verilog functions.
There is no way to wrap variable args in a $display.
So your best bet is using dynamic or associative arrays of strings or queues.
The following is an example of a possible use of an associative array:
package pkg;
function void multstr(string args[int]);
for(int i = 0; i < args.num; i++) begin
$display("arg%0d: %s", i, args[i]);
end
endfunction
endpackage
module testme();
string strings[int];
initial begin
strings[0] = "hello ";
strings[1] = "world";
pkg::multstr(strings);
end
endmodule

Answer 3

Create a function with a dynamic array port like this:
module tb ();
// function arg is a dynamic array of strings
function void printStrings(string mystrings[]);
foreach(mystrings[i])
$display("",mystrings[i]);
endfunction
// dynamic array of string
string names [];
initial
begin
names = new[2];
names = '{"bob","joe"};
printStrings(names);
$display("-----");
// make the d-array 1 bigger
names = new[names.size() + 1](names);
names = '{"bob","joe","bill"};
printStrings(names);
end
endmodule
Which produces
bob
joe
-----
bob
joe
bill
The same thing could be done using a queue as a function port rather than a d-array.