There is something known as a covergroup type option. One of these is the strobe option (see 18.2 page 305 and 18.6.1). The strobe option is used to prevent a coverage point from being sampled more than once in the same time step. When the strobe option is specified for a covergroup the corresponding coverage points are sampled in the Postponed region. The strobe option seems to be one way to deal with multiple matches when a sequence is used as a covergroup clocking event. Neil Eduard Cerny wrote On 01/15/07 07:10,: > True... actually I missed that in the LRM. But is this a good solution? > Would uniqueness even if chosen non-deterministically be better? (I > know, local variables...) > > ed > > > >>-----Original Message----- >>From: John Havlicek [mailto:john.havlicek@freescale.com] >>Sent: Monday, January 15, 2007 9:33 AM >>To: Eduard.Cerny@synopsys.COM >>Cc: john.havlicek@freescale.com; tej_singh@mentor.com; sv-ac@eda.org >>Subject: Re: [sv-ac] sequence as clocking event to covergroup >> >>Hi Ed: >> >>Your suggestion contradicts what we already have >>written about first_match in section 17. >> >>Do you intend to make this inconsistent with the >>currently existing first_match semantics? >> >>J.H. >> >> >>>X-MimeOLE: Produced By Microsoft Exchange V6.5 >>>Content-class: urn:content-classes:message >>>Date: Mon, 15 Jan 2007 06:27:41 -0800 >>>Thread-Topic: [sv-ac] sequence as clocking event to covergroup >>>Thread-Index: Acc3Yk/jxmzGV+eTSIWbGNAy5ZE/HwBTrOYg >>>From: "Eduard Cerny" <Eduard.Cerny@synopsys.com> >>>Cc: <sv-ac@eda.org> >>>X-OriginalArrivalTime: 15 Jan 2007 14:27:43.0158 (UTC) >> >>FILETIME=[5187F560:01C738B1] >> >>>Hi John, >>> >>>I agree with you that the covergroup should trigger on >> >>multiple matches >> >>>of a seuqnce, but I think that with first_match it should >> >>give only one >> >>>match even if there are possible multiple matches (by choosing >>>non-deterministically one of them).=20 >>> >>>Regards, >>>ed >>> >>> >>> >>>>-----Original Message----- >>>>From: owner-sv-ac@eda.org [mailto:owner-sv-ac@eda.org] On=20 >>>>Behalf Of John Havlicek >>>>Sent: Monday, January 08, 2007 9:31 AM >>>>To: tej_singh@mentor.com >>>>Cc: sv-ac@eda.org >>>>Subject: Re: [sv-ac] sequence as clocking event to covergroup >>>>=20 >>>>Hi Tej: >>>>=20 >>>>I have a few comments. >>>>=20 >>>>It is true that the LRM does not give a complete definition of >>>>multiplicity of matching and of when matching occurs. On >> >>the other >> >>>>hand, the LRM also does not leave these things completely >> >>undefined. >> >>>>=20 >>>>I think that if a covergroup has a sequence instance as >> >>its clocking >> >>>>event, then multiple matches of the sequence instance in the same >>>>timestep should result in multiple triggerings of the covergroup. >>>>=20 >>>>I think we should avoid allowing the rules for multiplicity=20 >>>>of covergroup >>>>triggering on sequences to differ from the rules for >> >>multiplicity of >> >>>>matching that apply in other scenarios, e.g. >>>>=20 >>>> cover property ( >>>> @(posedge clk) >>>> sequence_instance ##0 (1, task_call); >>>> ); >>>>=20 >>>>I don't like the idea of trying to incorporate >> >>first_match into the >> >>>>semantics of covergroups with sequence clocking event. I >> >>think the=20 >> >>>>user can use first_match in defining a sequence, but then >> >>the general >> >>>>rules for multiplicity of sequence matching should apply. >>>>=20 >>>>In particular, a first_match can have multiplicity, e.g. if both >>>>a ##1 b and c ##1 d match over a two-cycle interval, then=20 >>>>=20 >>>> first_match((a ##1 b) or (c ##1 d)) >>>>=20 >>>>should match with multiplicity two over that interval. >>>>=20 >>>>Best regards, >>>>=20 >>>>John H. >>>>=20 >>>> >>>>>X-Authentication-Warning: server.eda-stds.org: majordom set=20 >>>> >>>>sender to owner-sv-ac@eda.org using -f >>>> >>>>>X-MimeOLE: Produced By Microsoft Exchange V6.5 >>>>>Content-class: urn:content-classes:message >>>>>Date: Wed, 6 Dec 2006 15:12:02 -0800 >>>>>X-MS-Has-Attach:=20 >>>>>X-MS-TNEF-Correlator:=20 >>>>>Thread-Topic: [sv-ac] sequence as clocking event to covergroup >>>>>Thread-Index: = >>> >>>AccZfiKOmZ5lYIN/QgGxOLcn04V72QABWXHgAAFLp5AAAHSA7A=3D=3D >>> >>>>>From: "Singh, Tej" <tej_singh@mentor.com> >>>>>Cc: <sv-ac@eda.org> >>>>>X-OriginalArrivalTime: 06 Dec 2006 23:12:03.0364 (UTC)=20 >>>> >>>>FILETIME=3D[F0C06E40:01C7198B] >>>> >>>>>X-Virus-Status: Clean >>>>>Sender: owner-sv-ac@eda.org >>>>>=20 >>>>>This is a multi-part message in MIME format. >>>>>=20 >>>>>------_=3D_NextPart_001_01C7198B.F0397F78 >>>>>Content-Type: text/plain; >>>>> charset=3D"iso-8859-1" >>>>>Content-Transfer-Encoding: quoted-printable >>>>>=20 >>>>>But as Doron pointed out, the LRM does not define the=20 >>>> >>>>number of threads. >>>> >>>>>=20 >>>>>How about defining it so that the number of events at a=20 >>>> >>>>clock is same as >>>> >>>>>number of sequence attempts that matched at that clock.=20 >>>> >>>>This is what I =3D >>>> >>>>>was trying >>>>>to do with first_match but first_match will kill any >> >>future matches. >> >>>>>=20 >>>>>So for a sequence expr that looks like >>>>>=20 >>>>>a ##[1:$](b ##1 c) or (d ##1 e) >>>>>=20 >>>>>it will not matter whether 'or' results in two matches or=20 >>>> >>>>one match =3D >>>> >>>>>since >>>>>both correspond to the same attempt.=3D20 >>>>>=20 >>>>>Tej >>>>>=20 >>>>>=20 >>>> >>>>=20 >>>>--=20 >>>>This message has been scanned for viruses and >>>>dangerous content by MailScanner, and is >>>>believed to be clean. >>>>=20 >>>>=20 >> > -- --------------------------------------------------------------------- Neil Korpusik Tel: 408-720-4852 Senior Staff Engineer Fax: 408-720-4850 Frontend Technologies - ASICs & Processors (FTAP) Sun Microsystems email: neil.korpusik@sun.com --------------------------------------------------------------------- -- This message has been scanned for viruses and dangerous content by MailScanner, and is believed to be clean.Received on Tue Jan 16 10:34:11 2007
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