Here are my two cents. > 1) The statement about the range of values is not right or is confusing. Agreed. Rather than "the range is established", using "the range is contained" would be more accurate. However, I'm not sure if that is even useful. Perhaps we should just consider removing that sentence. > 2) What does it mean that sampled values containing X or Z are excluded. It means that a "?"only matches 0 and 1, X and Z are excluded. > 3) How many bins are created for > wildcard bins bx[] = { 4'b?0?0, 4'b?000, 4'b00?0 } > I would expect that 3 bins are created. Yes. It should create 3 bins. > 4) How are wildcard ignore_bins handled? > ... > The ignore value 2'b00 will be removed from the first BA bin causing the bin to be ignored. > Will the ignore value 2'b?0 remove the 2'b10 value from BB ? Yes. It should be removed. Arturo -----Original Message----- From: owner-sv-ec@eda.org [mailto:owner-sv-ec@eda.org] On Behalf Of Bresticker, Shalom Sent: Wednesday, May 10, 2006 4:15 AM To: Ryan, Ray; sv-ec@eda.org Subject: RE: [sv-ec] semantics of wildcard bins Hi, Ray. As a user reading this section for the first time, here are the interpretations I would come to as answers to your questions: > -----Original Message----- > From: owner-sv-ec@server.eda.org [mailto:owner-sv-ec@server.eda.org] On > Behalf Of Ryan, Ray > Sent: Wednesday, May 10, 2006 3:49 AM > To: sv-ec@server.eda.org > Subject: [sv-ec] semantics of wildcard bins > > The last last paragraph of the section on wildcard bins (18.4.3) states: > > "A wildcard bin definition only considers 2-state values; sampled values > containing X or Z are excluded. Thus, the range of values covered by a > wildcard bin is established by replacing every wildcard digit by 0 to > compute the low bound and 1 to compute the high bound." > > > 1) The statement about the range of values is not right or is confusing. > > For example: > wildcard bins bx = { 4'b?0?0 }; > This does not cover the values in the range 0000 to 1010. It doesn't > cover 0001. > [Shalom] Agree. > 2) What does it mean that sampled values containing X or Z are excluded. > > For example: > wildcard bins bx = { 4'b?0?0 }; > I would expect that if the sample value is: > 0000 - increment the bin count > 1000 - increment the bin count > 0001 - don't increment > 000X - don't increment > 0010 - increment > 00X0 - increment > 00Z0 - increment > However, the text seems to indicate that the last two sample values > are excluded and > so don't increment the bin count. > [Shalom] Yes, they are excluded. The text explicitly says that the ? is a wildcard for 0 and 1 and that it works like ==?. > 3) How many bins are created for > wildcard bins bx[] = { 4'b?0?0, 4'b?000, 4'b00?0 } > I would expect that 3 bins are created. > [Shalom] Agree. > 4) How are wildcard ignore_bins handled? > For example: > bins BA[2] = { 2'b00, 2'b1x }; > bins BB[2] = { 2'b10, 2'b0x }; > wildcard bins BC = { 2'b0?, 2'b11 } > wildcard ignore_bins ivals = { 2'b00, 2'b?0, 2'b0? }; > ignore_bins vals = { 2'b01, 2'b00, 2'b0x, 2'b0z }; > > The ignore value 2'b00 will be removed from the first BA bin causing > the > bin to be ignored. > Will the ignore value 2'b?0 remove the 2'b10 value from BB ? [Shalom] Yes. > Will the list of values in the last ignore_bins remove the wildcard > value 2'b0 from BC ? [Shalom] Yes. Two more editorial quibbles: The first example in this section is called g12_16 and increments "when the sampled value is between 12 and 16". Actually the range is only 12-15. Also, the first and third paragraphs in this section refer to "wildcard bins", with both in Courier font. As a reader, I would be in doubt whether or not this implies that 'wildcard' may only be used with 'bins' and not with 'ignore_bins' and 'illegal_bins' (going back to the rule that the BNF does not contain all the information and the text supplements it). The simplest correction would be to de-Courierize "bins' in those two places. ShalomReceived on Thu May 11 10:56:50 2006
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