Can we return data from SystemVerilog task?

SystemVerilog
, ,
1

Hi All,

Can we return data from System verilog task?
Does its possible or any work around?

Thanks,
Mehul

1 Like
2

In reply to mehul.gor:

User-defined SV tasks can have output arguments.

3

A task may have output arguments whose values are assigned upon returning from the task.
If an input argument is a class reference, you can update the class object by reference at any time during the task call.

1 Like
4

In reply to dave_59:

I am using DPI for interface of C and System verilog.

In C code, i am using below function which return data from given address using READ function.

data = READ(address);

READ function require to be blocking as it perform read operation via system verilog driver.

I have defined READ task in system verilog. But how to return data from this READ task?

5

In reply to mehul.gor:

In Verilog/SystemVerilog, a potentially time consuming routine must be written as a task.

task READ_DPI(input int address, output int data);
  #100 data = MEM[address];
endtask
export "DPI-C" task READ_DPI;

If you compile this code generating a DPI header file, it will produce this prototype:

DPI_LINK_DECL int
READ_DPI(
    int address,
    int* data);

An output argument is passed by reference in C. Note that the int return value of a DPI exported task is used for disables, and can be ignored if not used.
Your code can call this routine as:

#include "dpi.h"
...
READ_DPI(address,&data);
...

If you really need the READ routine to be a function in C, you can put a wrapper around it:

int READ(
  int address) {
  int data;
  READ_DPI(address &data);
  return data;
}
6

In reply to dave_59:

It Works! Thanks Dave.