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# modeling a constraint for a signal that is only high once (ever)

Last post Wed, Nov 15 2006 12:47 PM by archive. 5 replies.
 Started by archive 15 Nov 2006 12:47 PM. Topic has 5 replies and 1479 views
• #### Wed, Nov 15 2006 12:47 PM

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modeling a constraint for a signal that is only high once (ever)
 How can I model a constraint for a signal that is supposed to be high only oncein PSL?Originally posted in cdnusers.org by ssa
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• #### Wed, Nov 15 2006 1:37 PM

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RE: modeling a constraint for a signal that is only high once (ever)
 What about:// psl assume_single_high_pulse: assume {!a[*];[a];!a[*]};Originally posted in cdnusers.org by jb
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• #### Wed, Nov 15 2006 2:54 PM

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RE: modeling a constraint for a signal that is only high once (ever)
 Thanks jb.Tried it but it seems not to work.I can get two times a - even consecutively with this constraint applied.Might be due to to the last term in the sequence !a[*] - where !a[*0] (meta code) is a legal match.Any other suggestions?Originally posted in cdnusers.org by ssa
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• #### Wed, Nov 15 2006 3:23 PM

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RE: modeling a constraint for a signal that is only high once (ever)
 You need another constraint:// psl assume_no_second_pulse : assume never {a; !a[*]; a};Originally posted in cdnusers.org by foster
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• #### Wed, Nov 15 2006 4:57 PM

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RE: modeling a constraint for a signal that is only high once (ever)
 The following single constrtaint seems to work:// psl no2a: assume never { a[->2] };It doesn't say that 'a' has to occur once, it only says that it can't occur twice.Originally posted in cdnusers.org by TAM
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• #### Wed, Nov 15 2006 5:17 PM

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RE: modeling a constraint for a signal that is only high once (ever)
 Thanks guys - both never version work great.I found another alternative: never {a[=2]};Originally posted in cdnusers.org by ssa
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