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Conformal

Last post Tue, Mar 13 2007 11:07 PM by archive. 5 replies.
 Started by archive 13 Mar 2007 11:07 PM. Topic has 5 replies and 2093 views
• Tue, Mar 13 2007 11:07 PM

• archive
• Joined on Fri, Jul 4 2008
• Posts 88
• Points 4,910
Conformal
 ```I have run into an issue: there is an 8-bit input bus. The 4 MSBs and the 4 LSBs are related: the LSBs are simply the inversion of the MSBs. So sel[7] = ~sel[3], sel[6] = ~sel[2], etc. The original code used all 8 bits of sel (for reasons that I can only guess). There isn't any reason to do this in the behavioral code, and in fact it makes the code a lot less readable. The problem is that sel is an input port, so LEC won't pass unless either: 1. I use sel the way it was used in the original code 2. I can tell Conformal the relationship between sel[7:4] and sel[3:0]. Do anyone know a way to achieve the second option? I'd guess that conformal supports this, but I have no idea how. Thanks, Prasad```Originally posted in cdnusers.org by anssprasad
• Post Points: 0
• Wed, Mar 14 2007 4:54 AM

• archive
• Joined on Fri, Jul 4 2008
• Posts 88
• Points 4,910
RE: Conformal
 I see that there is some formatting problem, so I am reposting with numerics replaced by english words:`I have run into an issue: there is an 8-bitinput bus. The 4 MSBs and the 4 LSBs are related: the LSBs are simply theinversion of the MSBs. So sel[seven] = ~sel[three], sel[six] = ~sel[two], etc.The original code used all 8 bits of sel (for reasons that I can onlyguess). There isn't any reason to do this in the behavioral code, and infact it makes the code a lot less readable. The problem is that sel is aninput port, so LEC won't pass unless either: 1. I use sel the way it was used in the original code 2. I can tell Conformal the relationship between sel[seven:four] andsel[three:zero].Do anyone know a way to achieve the second option? I'd guess that conformalsupports this, but I have no idea how.Thanks,Prasad`Originally posted in cdnusers.org by anssprasad
• Post Points: 0
• Wed, Mar 14 2007 7:06 AM

• archive
• Joined on Fri, Jul 4 2008
• Posts 88
• Points 4,910
RE: Conformal
 Hi PrasadHere's one way to handle it in Conformal:add pin constraint one_hot sel[7] sel[3] -goldenadd pin constraint one_hot sel[6] sel[2] -goldenadd pin constraint one_hot sel[5] sel[1] -goldenadd pin constraint one_hot sel[4] sel[0] -goldenWith these set then logic like this would pass: golden assign out1 = sel[7]&sel[3] | sel[6]&sel[2] | sel[5]&sel[1] | sel[4]&sel[0]; revised assign out1 = 1'b0;ChrystianOriginally posted in cdnusers.org by croy
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• Wed, Mar 14 2007 1:56 PM

• archive
• Joined on Fri, Jul 4 2008
• Posts 88
• Points 4,910
RE: Conformal
 Chystian, There isn't a way to state inverted equivalence? Seems that would be more appropriate and provide more positive checking.Originally posted in cdnusers.org by bryan
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• Wed, Mar 14 2007 2:05 PM

• archive
• Joined on Fri, Jul 4 2008
• Posts 88
• Points 4,910
RE: Conformal
 Hi BryanYep, there is. That's why I said 'here's *one* way' :-)Here's another:add pin equi sel[7] -invert sel[3] -goldenadd pin equi sel[6] -invert sel[2] -goldenadd pin equi sel[5] -invert sel[1] -goldenadd pin equi sel[4] -invert sel[0] -goldenThe end result is the same but you're right that this is more explicit than 'one_hot'.ChrystianOriginally posted in cdnusers.org by croy
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• Thu, Mar 15 2007 10:37 PM

• archive
• Joined on Fri, Jul 4 2008
• Posts 88
• Points 4,910
RE: Conformal
 Thanks Chrystian,It was of great help.Prasad.Originally posted in cdnusers.org by anssprasad
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 Started by archive at 13 Mar 2007 11:07 PM. Topic has 5 replies.
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