Subject: RE: [vhdl-200x] Re: TBV2: Associative arrays proposal submitted
From: Erich Marschner (erichm@cadence.com)
Date: Mon Apr 28 2003 - 13:51:13 PDT
One of the reasons for modeling a bus as a bit-vector is the fact that values of different data types may be transferred via the same bus. The same can be said of memories. If you have to convert a real number to an integer in order to send it over a bus, or store it in memory, significant information will be lost. If you map each data type to be transferred to a (portion of a) bit-vector, no information is lost.
Erich
-------------------------------------------
Erich Marschner, Cadence Design Systems
Senior Architect, Advanced Verification
Phone: +1 410 750 6995 Email: erichm@cadence.com
Vmail: +1 410 872 4369 Email: erichm@comcast.net
| -----Original Message-----
| From: Allan Herriman [mailto:allan_herriman@agilent.com]
| Sent: Monday, April 28, 2003 2:24 PM
| To: Farrell Ostler
| Cc: Jim Goeke; Jim@synthworks.com; vhdl-200x@eda.org
| Subject: Re: [vhdl-200x] Re: TBV2: Associative arrays
| proposal submitted
|
|
| Farrell Ostler wrote:
| >
| > Jim Goeke wrote:
| >
| >
| >>It may be how people have historically written models but
| should we continue to
| >>bank on that? In the past there were many tool
| constraints that prevented using
| >>anything but vectors, that is no longer the case. We have
| written complete
| >>(synthesizable) designs using integer based types for for
| everything except the
| >>usual cast of control bits where it doesn't make much
| sense. With properly
| >>ranged integer subtypes the tools now do the "right" thing.
| >
| >
| > Have you been bothered much by the fact that integers are
| not guaranteed
| > to have a range larger than -2^31-1 to 2^31-1?
|
| In practice a simulator or synthesiser on a 32 bit platform
| will give
| you a range of -2^31 to 2^31-1. I don't know of any exceptions.
|
| This doesn't help if you have a > 32 bit address bus though.
|
| Regards,
| Allan.
| --
| Allan Herriman
| Advanced Networks Division +61 3 9210 5527 Tel
| Agilent Technologies, Inc. +61 3 9210 5550 Fax
| 347 Burwood Highway Forest Hill 3131 Australia
|
|
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