Re: [sv-bc] question about integer expression

From: Greg Jaxon <Greg.Jaxon_at_.....>
Date: Thu Apr 02 2009 - 19:43:44 PDT

Greg Jaxon shoulda wrote:

John,

    I also believe the answer is "no" for the purpose of establishing
what such constructs mean, so for example there is no 32-bit "context"
to possibly affect the arithmetic of those self-determined expressions.
Similarly I read identities like the A[E+:W] <=> A[E:E+W-1] that Arturo
cites as ideals rather than literal formulas (E and W's types never
interact).  One I had to cope with recently is the idea that declaring
"C[expr]" means C[0:(expr)-1] - don't take that one too literally either!

But the "no" comes with a qualification - an economical implementation
usually has limits when trying to serve extremes here.  While there is
no semantic bias toward 32-bit arithmetic, there are huge practical
biases.  A portable RTL design would be foolish to count on any larger
range.
  

Prescriptively, the standard should say "integral expression".  But, in
conforming RTL, any index or bounds value should be representable as a
native integer on the host machine.

Greg

Disclaimer: JMHO -  not a voting position.
  

--
This message has been scanned for viruses and
dangerous content by MailScanner, and is
believed to be clean. Received on Thu Apr 2 19:45:39 2009