[sv-ac] Re: P1800-2009 : Contradictions in legality of type "event" in formal argument

Sorry, but after more thoughts, it makes sense since a local variable formal
argument, or even a local variable cannot write an event.  However, a formal
argument can be used as a trigger in the sequence or a property (not sure if
formal argument of a property can be an event).  Ben

On Sun, May 10, 2009 at 12:13 AM, ben cohen <hdlcohen@gmail.com> wrote:

> An errata to my last comment: It strikes me as odd, particularly, the way
> I view it, a formal argument, by default of direction input, acts the same
> as a local variable formal argument of direction input.  Yet, type argument
> of type event is legal if formal argument is not declared as a local
> variable formal argument.
> I meant to say, It strikes me as odd, particularly, the way I view it, a
> non-local formal argument, by default of direction input, acts  as a local
> variable formal argument of direction input it is it not written into it
> (i.e., can write into a local variable formal argument, but not into a
> non-local formal argument).  Yet, type argument of type event is legal if
> formal argument is not declared as a local variable formal argument.
> Ben
>
> On Sat, May 9, 2009 at 10:01 PM, ben cohen <hdlcohen@gmail.com> wrote:
>
>> Reading draft 8, (same in draft 7), I found the following, which sounds
>> like contradictions in that type event, declared as illegal in 16.6.1Operand types, is used as formal argument, but is
>> illegal in local variable formal argument.  Specifically:
>> 16.8.1 Typed formal arguments in sequence declarations
>> If a formal argument of a named sequence is typed, then the type shall be
>> sequence, event, or one of the
>> types allowed in 16.6.1
>> [Ben Cohen] Interestingly, 16.6.1 specifies "event" as illegal.  Thus,
>> this is an exception.
>> p321
>> The following shows an example of a formal argument with event type:
>> sequence event_arg_example (event ev);
>> @(ev) x ##1 y;
>> endsequence
>>
>> 16.8.2 Local variable formal arguments in sequence declarations
>> p322
>> sequence illegal_loc_var_formal (
>> output logic a, // illegal: local must be specified with
>> ...
>> local event e, // illegal: event is a type disallowed in
>> // 16.6.1
>> ---
>> 16.6.1 Operand types
>> The following types are not allowed:
>> Noninteger types (shortreal, real, and realtime)
>>  string
>>  event
>>  chandle
>>  class
>>  Associative arrays
>>  Dynamic arrays
>> [Ben Cohen] So, If I understand this correctly, a typed formal argument
>> that is declared with local is illegal, but if declared without the local
>> is legal.
>> Thus, updating the example on page 321, I can say the following:
>> sequence event_arg_example_Ben (
>>     local inout logic a,
>>                       logic e, f,
>>     local event evt,      // illegal: event is a type disallowed
>> in 16.6.1
>>              event ev);  // Legal: Exception to rules in 16.6.1, as
>> per 16.8.1
>> @(ev) a ##1 e;
>> endsequence
>> It strikes me as odd, particularly, the way I view it, a formal argument,
>> by default of direction input, acts the same as a local variable formal
>> argument of direction input.  Yet, type argument of type event is legal if
>> formal argument is not declared as a local variable formal argument.
>> Where am wet here?
>> Ben
>>
>>
>>
>

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