Can we use an expression in consecutive repetition operator

SystemVerilog
,
1

Hi,
Can we use an expression in consecutive repetition operator.
Originally the syntax is signal_name[*number];
but instead of number can i give an expression(gives the same number). I executed the below code but it shown error. If it is possible then give me a small sample code for understanding.

[*(len_array[start_id].pop_front)] is it valid or not?

module assertions;
int count[int];
bit [7:0] len_array[int][$];

property wlast;
@(negedge ACLK) disable iff(!ARESETn)
(WVALID && WREADY) |-> (count[start_id]+1)[*(len_array[start_id].pop_front)] |=> WLAST;
endproperty

WLAST_ASS : assert property(wlast);
endmodule

2

In reply to Siva91221:

If you look at the SV LRM Section 16.9.2 Repetition in sequences you’ll find that
— Consecutive repetition ( *[const_or_range_expression] ): Consecutive repetition specifies finitely many iterative matches of the operand sequence…

So your expression is not a constant or a range expression, based on this I’d say it is not allowed, but have you tried it out?

HTH,

-R

3

In reply to rgarcia07:
int var;
signal_name[*var] is illegal
Do this instead

 
int var=5;
// a[*var] replacement 
properly p;
 int v;
 (b, v=var)|-> 
first_match((a, v=v-1'b1)[*0:$] ##1 v==0) ##1 c; // or ##0 c depends on requirements 
endproperty

Ben Cohen
http://www.systemverilog.us/ ben@systemverilog.us
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4

In reply to ben@SystemVerilog.us:

Another option is to use my package at
https://verificationacademy.com/forums/systemverilog/sva-package-dynamic-and-range-delays-and-repeats

The package includes a tb.
Example

 
    sequence q_dynamic_repeat(q_s, count);
        int v=count;
        (1, v=count) ##0 first_match((q_s, v=v-1'b1) [*1:$] ##0 v<=0);
    endsequence

// in the module 
    bit clk, a, b, c=1, w;  
    int d1=2, d2=5;  

    sequence q_s;
        a ##1 c; 
    endsequence 
// ******       DYNAMIC REPEAT q_s[*d1] **********
    // Application:  $rose(a)  |-> q_dynamic_repeat(q_s, d1) ##1 my_sequence;
    ap_rpt: assert property(@ (posedge clk) 
      $rose(a)|-> q_dynamic_repeat(q_s, d1)  ##1 my_sequence);

Ben

5

In reply to rgarcia07:

In reply to Siva91221:
If you look at the SV LRM Section 16.9.2 Repetition in sequences you’ll find that
— Consecutive repetition ( *[const_or_range_expression] ): Consecutive repetition specifies finitely many iterative matches of the operand sequence…
So your expression is not a constant or a range expression, based on this I’d say it is not allowed, but have you tried it out?
HTH,
-R

Hi,
I tried the above mentioned code but it shows that expressions are not allowed in consecutive repetition operator.
So, that’s why i’m asking how can we approach that scenario?

6

In reply to Siva91221:

Use the package I linked above.
Ben