Using queues in recursive properties

Question

I have some data from a 1 bit serial port which comes in multiples of bytes of variant lengths as such:

byte expected_1 [$] = {8'hBA, 8'hDD, 8'hC0, 8'hDE};
byte expected_2 [$] = {8'h01, 8'h23, 8'h45, 8'h67, 8'h89, 8'hAB, 8'hCD, 8'hEF};  

At each positive clock edge, one bit is sent. I need to testbench hundereds of sequences ( maybe thousand in the future ) so I want to automate the process with assertions in system verilog. The new 2012 standard allows for queues to be passed to properties, but can the queues be sent though a recursive property? I received some error about hierarchical ref.

This is what I have so far (with help from @Greg here):

default clocking sck @(posedge sck); endclocking : sck  

sequence seq_serial(logic signal, logic [7:0] expected); // check each bit
  byte idx = 7;
  (signal == expected[idx], idx--)[*8];
endsequence : seq_serial

property recurring_queue(bit en, logic data, byte data_e [$])
  int queue_size = data_e.size;
  logic [7:0] expected = data_e.pop_front(); 

  if(queue_size != 0) (
    !en throughout (seq_serial(data, expected) ##1 recurring_queue(en, data, data_e))
  );

endproperty : recurring_queue

`define ez_assert(exp)
   assert property (recurring_queue(en, data, exp))
   else $error("Bad Sequence @ time: %t. Info: %m", $time);

Calling the assertion in my testbench should be as easy as this:

A1 : `ez_assert(expected_1);

The error messages read:

1) passing hierarchical ref to be used in another hierarchical ref is not supported 
2) Illegal SVA property in RHS of'##' expression 
3) Local variable queue_size referenced in expression before getting initialized

I'm open to other ideas for asserting long variable-length serial sequences.

Answer 1

Try the same strategy as seq_serial:

sequence seq_queue_pattern(bit en, logic data, byte expt_queue [$]);
    int qidx = 0;
    ( !en throughout (seq_serial(data,expt_queue[qidx]), qidx++)[*] )
    ##1 (qidx==expt_queue.size);
endsequence : seq_queue_pattern

asrt_expected_1 : assert property ( $fell(en) |-> seq_queue_pattern(en,data,expected_1));
asrt_expected_2 : assert property ( $fell(en) |-> seq_queue_pattern(en,data,expected_2));

This assertion will fail if en is high or the seq_serial chain does not match expected. Do not that parenthicy location matters:

• en is don't care one clock after final seq_serial completes:
  • ( !en throughout (seq_serial(data,expt_queue[qidx]), qidx++)[*] ) ##1 (qidx==expt_queue.size)
• en must be low one clock after final seq_serial completes or failes and don't care after that
  • !en throughout ( (seq_serial(data,expt_queue[qidx]), qidx++)[*] ##1 (qidx==expt_queue.size) )
• en must be low one clock after final seq_serial completes and don't care after that
  • !en throughout ( (seq_serial(data,expt_queue[qidx]), qidx++)[*] ##1 (qidx==expt_queue.size) ) ##1 (qidx==expt_queue.size)

Queues within sequences and properties are new and may not be fully supported by all simulators yet. To work around this limitation, use a parametrized macro to create a sequence for each expected queue stream:

`define asrt_qpat(en,monitor, expt_queue) \
    sequence seq_queue_pattern__``expt_queue (bit en, logic data); \
        int qidx = 0; \
        (!en throughout (seq_serial(data,expt_queue[qidx]), qidx++)[*]) \
        ##1 (qidx==expt_queue.size); \
    endsequence : seq_queue_pattern__``expt_queue \
    \
    asrt_``expt_queue : assert property( @(posedge clk) \
        $fell(en) |=> seq_queue_pattern__``expt_queue (en,monitor) ) \
    else $error("Bad Sequence @ time: %t. Info: %m", $time);

`asrt_qpat(en,data[0],expected_1)
`asrt_qpat(en,data[1],expected_2)