| Add Proposal | Add Analysis | Edit Class, Environment, or Release |
| Number | 580
|
| Notify-List |
|
| Category | enhancement
|
| Synopsis | Add some system functions for use in constant expressions
|
| State | open
|
| Class | enhancement
|
| Arrival-Date | May 05 2004
|
| Originator | sharp@cadence.com (Behavioral Task Force)
|
| Release |
|
| Environment |
|
| Description |
If enhancement/387 is approved, allowing certain system functions to be used in constant expressions, there may be some new system functions that would be useful with this. The most obvious example would be to add a ceiling-of-log-base-2 function, for use in setting address bus widths based on memory size, or data width needed to represent a certain maximum value. We would need to solicit other suggestions from users. I could suggest others that are difficult to compute generally with the existing operators, but I don't know if they are actually useful. Shalom seemed to think that some of them might be, though I don't know whether he meant in general or in constant expressions. Possible examples might include find-first-bit-set, though I think this could be computed fairly easily given a log-base-2 function. A find-first-bit-clear would be trivial to compute given a find-first-bit-set, using ~. These would find the MSB. Shalom also mentioned that finding the LSB set would be useful. It turns out that this can be computed given a function that finds the MSB set plus some additional math, though the tricks involved may not be widely known. Another related example might be a population count, which counts the number of set bits in a value. There are also some other enhancement requests that could be satisfied by new system functions (e.g. rotates, bit-reversal), and such functions would also be suitable for constant expressions (though they might not be useful there). Again, I don't think we should put any of these in unless they would actually be useful to users. |
| Fix |
Unknown |
| Audit-Trail |
From: Shalom Bresticker <Shalom.Bresticker@freescale.com> To: btf-bugs@boyd.com Cc: Subject: Re: enhancement/580: Add some system functions for use in constant expressions Date: Wed, 02 Jun 2004 09:38:54 +0300 MIN, MAX, and ABS functions would be useful. |
| Unformatted |
|
Hosted by Boyd Technology