[sv-ac] comments on mantis 1550 proposal

Ed:

Below are my comments.

J.H.

Comments on Sampled1550.070202.htm
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- "The value of $sampled is updated in the preponed scheduling region."  This is 
  consistent with "The value is stable throughout the timestep."  Note, however,
  that in the document that Cliff sent out it says that 

     Sampling in the Preponed region is equivalent to sampling in the
     previous Postponed region.

  Do you know if it is possible for PLI calls in the Postponed and
  Preponed regions to see a difference between updating $sampled in
  the Preponed rather than the previuos Postponed region?

- In the following

    For example, if $sampled(y) is called at time 0, and y is of type
    logic, the value returned is X.

  I'm not sure "y" has been specified enough -- shouldn't we say that 
  y is not a static variable with declaration assignment?

- There seems to be a divergence between $past and $rose, etc. when the
  clock tick is before the start of simulation.  For $past, shouldn't we 
  change

    If the specified clock tick in the past is before the start of
    simulation, the returned value from the $past function is the
    value assigned in the declaration of the variable if the argument
    is a static variable, or in the absence of such an assignment or
    if the argument is an expression then it is the default value of
    the type of the argument.

  to

    If the specified clock tick in the past is before the start of
    simulation, the returned value from the $past function is the
    result of evaluating the expression using the initial values of
    the variables comprising the expression. The initial value of a
    static variable is the value assigned in its declaration, or in
    the absence of such an assignment it is the default (or
    uninitialized) value of the corresponding type. The initial value
    of any other variable or signal is the default value of the
    corresponding type.

  ?

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