Re: assign out = mem[index] ;

From: Steven Sharp (sharp@cadence.com)
Date: Mon Aug 12 2002 - 16:05:56 PDT


Precedence: bulk

>> That is, if mem[index] changes while index stays constant,
>> is out updated ?
>>
>> Mac claims it is.
>
>I agree. In fact, if index changes but mem[index]
>doesn't, there is no update.
>
>Of course the only way to observe this is to have a
>function call with side effects in the expression.

A test with Verilog-XL indicates that if index changes but mem[index]
doesn't, then it does still evaluate the expression (at least if there
is a function call with a side effect in the expression). Were you
testing with a different simulator, such as VCS?

I think this is one of those things that is implementation-dependent.

On the other hand, if mem[index] changes even though index does not,
then an implementation must evaluate the expression and update out.

Steven Sharp
sharp@cadence.com



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