In reply to Tobi:
There is nothing wrong with your code.
The issue may be that the antecedent is never retriggered. Below is a test of your code with debug features added. Try this model with your simulator.
import uvm_pkg::*; `include "uvm_macros.svh"
module top;
timeunit 1ns; timeprecision 100ps;
bit clk, a, b, data_rd, rst=0;
bit[3:0] data;
int count;
event e160, e_attempt;
default clocking @(posedge clk);
endclocking
initial forever #10 clk=!clk;
always @(posedge clk) begin
count <= count + 1'b1;
if (count==160) -> e160;
end
function void attempt();
-> e_attempt;
endfunction
ap160: assert property (@(posedge clk) disable iff(rst)
count > 160 ##0 ($rose(data_rd) && (data[3:0] !=7), attempt())
|-> $past((data[3:0]==7),160))
$display("PASS at cycle %d past(data[3:0])=%b",
$realtime, $sampled($past(data[3:0], 160)));
initial begin
bit va, vb;
repeat(500) begin
@(posedge clk);
if (!randomize(data_rd, data) with
{ data_rd dist {1'b1:=1, 1'b0:=3};
data dist {4:=1, 5:=2, 6:=1, 7:=4};
}) `uvm_error("MYERR", "This is a randomize error")
a <= va;
b <= vb;
end
$stop;
end
endmodule
** Error: Assertion error.
# Time: 3270 ns Started: 3270 ns Scope: top.ap160 File: C:/ben_play/./past160.sv Line: 20 Expr: $past(data[3:0]==7,160)
# PASS at cycle 3450 past(data[3:0])=0111
# ** Error: Assertion error.
# Time: 3530 ns Started: 3530 ns Scope: top.ap160 File: C:/ben_play/./past160.sv Line: 20 Expr: $past(data[3:0]==7,160)
# PASS at cycle 3630 past(data[3:0])=0111
# PASS at cycle 3750 past(data[3:0])=0111
# ** Error: Assertion error.
# Time: 3990 ns Started: 3990 ns Scope: top.ap160 File: C:/ben_play/./past160.sv Line: 20 Expr: $past(data[3:0]==7,160)
# ** Error: Assertion error.
# Time: 4310 ns Started: 4310 ns Scope: top.ap160 File: C:/ben_play/./past160.sv Line: 20 Expr: $past(data[3:0]==7,160)
# PASS at cycle 4690 past(data[3:0])=0111
# ** Error: Assertion error.
# Time: 4790 ns Started: 4790 ns Scope: top.ap160 File: C:/ben_play/./past160.sv Line: 20 Expr: $past(data[3:0]==7,160)
# ** Error: Assertion error.
# Time: 4990 ns Started: 4990 ns Scope: top.ap160 File: C:/ben_play/./past160.sv Line: 20 Expr: $past(data[3:0]==7,160)
# PASS at cycle 5190 past(data[3:0])=0111
# PASS at cycle 5310 past(data[3:0])=0111
# PASS at cycle 5390 past(data[3:0])=0111
# ** Error: Assertion error.
# Time: 5510 ns Started: 5510 ns Scope: top.ap160 File: C:/ben_play/./past160.sv Line: 20 Expr: $past(data[3:0]==7,160)
# PASS at cycle 5610 past(data[3:0])=0111
# ** Error: Assertion error.
# Time: 5790 ns Started: 5790 ns Scope: top.ap160 File: C:/ben_play/./past160.sv Line: 20 Expr: $past(data[3:0]==7,160)
# ** Error: Assertion error.
# Time: 5930 ns Started: 5930 ns Scope: top.ap160 File: C:/ben_play/./past160.sv Line: 20 Expr: $past(data[3:0]==7,160)
# PASS at cycle 6030 past(data[3:0])=0111
# ** Error: Assertion error.
# Time: 6070 ns Started: 6070 ns Scope: top.ap160 File: C:/ben_play/./past160.sv Line: 20 Expr: $past(data[3:0]==7,160)
# PASS at cycle 6370 past(data[3:0])=0111
# PASS at cycle 6570 past(data[3:0])=0111
# ** Error: Assertion error.
# Time: 6630 ns Started: 6630 ns Scope: top.ap160 File: C:/ben_play/./past160.sv Line: 20 Expr: $past(data[3:0]==7,160)
# ** Error: Assertion error.
# Time: 6830 ns Started: 6830 ns Scope: top.ap160 File: C:/ben_play/./past160.sv Line: 20 Expr: $past(data[3:0]==7,160)
# PASS at cycle 7150 past(data[3:0])=0111
# ** Error: Assertion error.
# Time: 7190 ns Started: 7190 ns Scope: top.ap160 File: C:/ben_play/./past160.sv Line: 20 Expr: $past(data[3:0]==7,160)
# ** Error: Assertion error.
# Time: 7330 ns Started: 7330 ns Scope: top.ap160 File: C:/ben_play/./past160.sv Line: 20 Expr: $past(data[3:0]==7,160)
# PASS at cycle 7450 past(data[3:0])=0111
# ** Error: Assertion error.
# Time: 7650 ns Started: 7650 ns Scope: top.ap160 File: C:/ben_play/./past160.sv Line: 20 Expr: $past(data[3:0]==7,160)
# PASS at cycle 7830 past(data[3:0])=0111
# ** Error: Assertion error.
# Time: 7910 ns Started: 7910 ns Scope: top.ap160 File: C:/ben_play/./past160.sv Line: 20 Expr: $past(data[3:0]==7,160)
Ben Cohen
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