SystemVerilog looping through hierarchy

Question

I have registers instantiated in a Register block Regblock as such:

DUT.Regblock.Register1
DUT.Regblock.RegisterA
DUT.Regblock.RegisterABC
...

All these registers have the same inner structure. I would like to simulate the effects of bit flips in these registers.

//Here an attempt to do bit flips
bitFlipLocation = $random;
force  DUT.RegBlock.Register1.reg[bitFlipLocation] = ~DUT.RegBlock.Register1.reg[bitFlipLocation];
release DUT.ABCStar1.RegBlock.Register1.reg[bitFlipLocation];

Is there a way to create a loop over all DUT.Regblock.Register1, RegisterA, RegisterABC, ... inside RegBlock and create these bit flips?

Answer 1

There are ways to do this, but not within the SystemVerilog language itself. You can write VPI code in C to iterate over block names and apply the forces use the C API. Or you can use tool specific commands to iterate of block names and use commands (usually Tcl) to apply the forces.

Both of those are beyond the scope of what can be shown in this forum.

Answer 2

Following dave's answer I implemented the VPI code in C to loop over all register within RegBlock and randomly force bit flips at some positions (register is 32 bit wide).

#include <sv_vpi_user.h>
#include <string.h>
#include <stdlib.h>
#include <stdio.h>
#define NULL 0

void reg_flips() {
  vpiHandle module_iter;
  vpiHandle module_obj;
  vpiHandle module_regblk;
  vpiHandle reg_nets;
  vpiHandle net;
  //Starting from the RegBlock
  module_regblk = vpi_handle_by_name("DUT.RegBlock",NULL);
  //Iterator over all register in RegBlock
  module_iter = vpi_iterate(vpiModule,module_regblk);
  while (module_iter) {
    module_obj = vpi_scan(module_iter);
    if (module_obj) {
      reg_nets = vpi_iterate(vpiReg,module_obj);
        while (reg_nets) {
          net = vpi_scan(reg_nets);
          if (net) {
            s_vpi_value val;
            val.format = vpiIntVal;
            val.value.integer = rand()%2;
            int position = rand()%32;
            //Forcing the value at a given position.
            vpi_put_value(vpi_handle_by_index(net,position),&val,NULL,vpiNoDelay);
          }
          else {
            reg_nets = NULL;
          }
        }
      }
    }
    else {
      module_iter = NULL;
    }
}