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N unique stable data vectors

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Working off the concept that a property like the following causes a formal tool to try all values of the stable_data wire...

wire [W-1:0] stable_data;
//psl assume_stable_data: assume always(stable(stable_data))@(posedge clk);

Is there a way to generate N stable_data vectors and at the same time guarantee that at any one time the data in them is unique.

If I just wanted 2 vectors I might do something like the following:

wire [W-1:0] stable_data0,stable_data1;
//psl assume_stable_data0: assume always(stable(stable_data0))@(posedge clk);
//psl assume_stable_data1: assume always(stable(stable_data1))@(posedge clk);

//psl assume_unique_data: assume always(
// stable_data0!=stable_data1
//)@(posedge clk);

Extending this to N vectors seems troublsome.  Any ideas?

One might also ask how to fill a NxW array with unique stable data.

Just for clarification, the fact that the data is stable isn't really a necessary component of this question.  I am mainly just wondering how I could easily generate N unique vectors of data.  It's just that data like this is usually stable in proofs.

Thanks,

Ross


Originally posted in cdnusers.org by weberrm
Parents

  • Hi Ross,

    I don't have an answer to the question of repeating N-Times the unique constraint, but other remarks:

    1) stable(stable_data))@(posedge clk) is only guaranteeing stability if the design is purely synchronous to the posedge, otherwise there may be arbitrary values at the clock high phase.

    2) The unique vector set is a subset of the generic vector set. IFV will apply any vector set to FAIL an assertion, including the one with unique vectors, I don't really see a need to restrict it to the unique set. Potential reason might be

    a) you don't like this CEX
    b) you need it for a coverage trace
    c) this is really a conatraint of the system and causes a false failure in an assertion

    Can you elaborat eon your motivation for this conatraints?

    Thanks,
    Joerg.


    Originally posted in cdnusers.org by foster
Reply

  • Hi Ross,

    I don't have an answer to the question of repeating N-Times the unique constraint, but other remarks:

    1) stable(stable_data))@(posedge clk) is only guaranteeing stability if the design is purely synchronous to the posedge, otherwise there may be arbitrary values at the clock high phase.

    2) The unique vector set is a subset of the generic vector set. IFV will apply any vector set to FAIL an assertion, including the one with unique vectors, I don't really see a need to restrict it to the unique set. Potential reason might be

    a) you don't like this CEX
    b) you need it for a coverage trace
    c) this is really a conatraint of the system and causes a false failure in an assertion

    Can you elaborat eon your motivation for this conatraints?

    Thanks,
    Joerg.


    Originally posted in cdnusers.org by foster
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