Finding Which Packed Indexes are 1

SystemVerilog
,
1

Hi ,

I want to find indexes which are 1’b1 .


bit [3:0] b = 4'b1010 ;
// I want Output as 3 , 1

LRM 7.12.1 has Array Locator methods .

Here is my sample code using find_index ::



 bit [3:0] b [1] = '{ 4'b1010 } ;
 int ind[$] ;

 initial begin

   foreach(b[,j]
 ind = b.find_index with ( b[item.index][j] == 1'b1 ? j : 0 ) ;

  $display("High Indexes are %0p",ind);

 end

The Queue is empty ( Since No index has a value of ‘j’ ) and No Indexes are Printed .

Needed assistance with the same

**Is it possible to skip the foreach and have some logic for the packed dimension ( j ) ??
**

2

In reply to Have_A_Doubt:

Hi,

It is always recommended to use the queue push_back() or push_front() method instead of assigning value directly to the queue.

3

In reply to srishis:

Actually , Array reduction methods return a queue .

Hence its necessary to use a Queue

4

In reply to Have_A_Doubt:

Please read the comments carefully. I have suggested you to use queue methods to assign a value.
// sample code


``` verilog

   ind.push_back(value); // get value based on the requirements.
5

In reply to srishis:

Well the Original Question does say using Array Locator methods
( which returns a Queue by default )

Also your original comment ::

“It is always recommended to use the queue push_back() or push_front() method instead of assigning value directly to the queue”

Is Incorrect in my case . The LRM clearly states these methods return a Queue .
It even has examples with the same

6

In reply to Have_A_Doubt:

You are right. Apology for my comment. Let me run this and debug the issue.

7

In reply to Have_A_Doubt:

Array locator methods operate only on unpacked arrays. Hence, I am assuming any operation on packed dimensions will not work.

8

In reply to Have_A_Doubt:

module top;
  bit qbit[$];
  int found[$];
  bit [3:0] b = 4'b1010;
  initial begin
    qbit = {<<{b}}; // convert packed bits to unpacked, reversing index order
    found = qbit.find_index() with (item == '1);
    $display("%p",found);
  end
endmodule