Re: [IBIS] BIRD135: Add Boolean to BNF for IBIS-AMI

With BIRD 135 ³Add Boolean to BNF for IBIS-AMI² scheduled for a vote
tomorrow this is late, but I have a question. The BIRD describes allowable
Boolean values only in a parenthetical comment:

|*8. Parameter values can be expressed either as a string literal, Boolean
|* literal (True or False), decimal number, or a floating point number in
|* the standard ANSI 'C' notation (e.g., 2.0e-9). String literal values
|* are delimited using a double quote (") and no double quotes are allowed
|* inside the string literals.

There is a similar parenthetical comment on page 140 where the Type
parameter values are listed.

| Type: (default is Float)
| Float
| Integer
| String
| Boolean (True/False)
| Tap (For use by TX and RX equalizers)
| UI (Unit Interval, 1 UI is the inverse of the data rate frequency,
| for example 1 UI of a channel operating at 10 Gb/s is 100 ps)

Since tools and models will have to decide if a submitted Boolean value is
true or false, it seems to me there should be more guidance. For example,
which of these are true and which are false, if any?

  true
  false
  yes
  no
  t
  0
  1
    <-- empty string

What to do if a value is not exactly "True" or "False"? One approach is for
the IBIS parser to reject any other value for Boolean parameters, as long as
it always knows the type expectation of every parameter (Boolean Table
contents, anyone?). Ibischk5 says nothing no matter which of the above
values I set a Boolean parameter to, so currently we can't count on this
kind of checking.

But it is not uncommon for languages that support Boolean types to
case-insensitively regard "true", "t", "yes", "y", or any non-zero number as
True, and all else as False. Should we add some exact description that
yields only two outcomes to the spec in this BIRD? What will existing tools
accept as true and false today?

Mike

On 6/15/11 4:50 PM, "Mirmak, Michael" <michael.mirmak@intel.com> wrote:

> The enclosed BIRD 135, Add Boolean to BNF for IBIS-AMI, is submitted on behalf
> of Arpad Muranyi of Mentor Graphics Corp. It will be discussed at the next
> IBIS Open Forum teleconference.
>
> A complete list of BIRDs is available at http://www.eda.org/ibis/birds/.
>
> Michael Mirmak
> Intel Corp.
> Chair, IBIS Open Forum
>

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