Stats

  • Locked Locked
  • Replies 4
  • Subscribers 125
  • Views 14075
  • Members are here 0
This discussion has been locked.
You can no longer post new replies to this discussion. If you have a question you can start a new discussion

Equality operators in Spectre

svcher

Hello,

What is a non-equality operator in Spectre?  Help says it is "!=".  However, this Spectre deck errors out:

simulator lang=spectre
opt options rawfmt=psfascii
v1 (1 0) vsource dc=x1
v2 (2 0) vsource dc=x2
parameters x = 0
parameters x1 = (x==0)
parameters x2 = (x!=0)
dc dc
save 1 2

The error message says:

Error found by spectre during circuit read-in.
    ERROR (SFE-874): "test.scs" 8: Unexpected equals "=". Expected close
        parenthesis.
    ERROR (SFE-683): "test.scs" 8: Badly formed parameters statement.

Line number 8 is the one where "x2" is defined.

Spectre version is "13.1.1.252.isr11 32bit -- 14 Aug 2014"

  Thank you for your help.

  • Hi Sergey,

    This appears to be a bug in the parser to me. If I use this:

    parameters x=0
    parameters x1=(x)==0
    parameters x2=(x)!=0

    then it works. I filed CCR 1446809 to get this corrected.

    Regards,

    Andrew.

  • Thank you Andrew, I will use the workaround you suggested while this gets fixed. BTW, this also works: parameters x2= x !=0. Notice an extra space before the "!=".

  • Actually it turns out that this is expected behaviour. It's a consequence that identifiers (net names, instance names, parameter names etc) are allowed to have exclamation marks in them - this is because Virtuoso uses the convention such as vdd! to indicate a global node, and many years ago we decided to allow such net names to be used in spectre unchanged (i.e. not mapped to something else). Because identifiers are found by the tokeniser, it can't use different rules for different identifiers (so an identifier can't only allow exclamation for net names). Partly this is because at the point of tokenisation it wouldn't know the context, but also because certain parameter values can be net names.

    So actually x2=x!=0 looks like ident1=ident2=0 which is not legal. So the solution is to add a space or surround with parentheses which separates the ! from the identifier.

    I'll write this up as a solution, as there's nothing we can fix here.

    Regards,

    Andrew.

  • Thanks Andrew, I understand now that this is a feature, not a bug.

Community Guidelines

The Cadence Design Communities support Cadence users and technologists interacting to exchange ideas, news, technical information, and best practices to solve problems and get the most from Cadence technology. The community is open to everyone, and to provide the most value, we require participants to follow our Community Guidelines that facilitate a quality exchange of ideas and information. By accessing, contributing, using or downloading any materials from the site, you agree to be bound by the full Community Guidelines.