In reply to SUNODH:
b[=2] // is equivalent to:
!b[*0:$] ##1 b ##1 !b[*0:$] ##1 b ##1 !b[*0:$]
a |=> b[=2] ##1 c ; // is eauivalent to
a |=> !b[*0:$] ##1 b ##1 !b[*0:$] ##1 b ##1 !b[*0:$] ##1 c;
// #35 clk=1, a=0, b=1, c=1 // Property Passed or Fail ?
// Because of !b[*0:$] ##1 c;
// property is false at time 35 because b==1
// It requires NO b before a c
// Assertion would fail
//
// If you had
#25 clk=1, a=0, b=1, c=0 // 2nd b=1
#30 clk=1, a=0, b=0, c=1
// If would pass because
b ##1 !b[*0:$] ##1 c
// get reduced to
b ##1 c // b==1 at 25, c==1 at 30
On your testbench, use nonblocking assignments (the <= ) instead of the blocking assignment.
Ben Cohen
http://www.systemverilog.us/ ben@systemverilog.us
** SVA Handbook 4th Edition, 2016 ISBN 978-1518681448
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