RE: [sv-bc] RE: [sv-ec] Are variable-width part selects already part of the SV language? (Mantis 2684)

A recent example was something like this:

We have a 128-bit input vector and a 128-bit replacement vector. N indicates the replacement point. That is, the output vector needs to be composed of bits [127:N] from the input vector and bits [N-1:0] of the replacement vector.

The actual case was more complex, and I am not sure I am summarizing it correctly.

So, the intutitive but illegal way to code this is

out[127:0] = { in[127:N], replace[N-1:0] } ;

To actually get this, you can do something like (I'm not sure this is correct):

{(in >> N), replace << (127-N)} >> N

There are other ways to do this.
All are ugly, non-intuitive, hard to read, and even harder to write correctly.
The fact that there are ways to do this means that there are ways to transform the currently illegal form into a legal form.
Why shouldn't this transformation be automatic instead of forcing the designer to waste his time doing code contortions and usually requiring several passes until he gets it correct?

> Often, what is needed is a combination of variable
> part-selects that adds up to a constant width, e.g., N bits
> from vector A, concatenated with 32-N bits from vector B.

Shalom
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