Re: [myhdl-list] essay about integer arithmetic

[Michael B. <ma...@cr...>]

Yes, but I intend for integers to represent fields of bits, and to do numerous
other things that are not constrained by intervals. In fact, some of those
things (involving plural, concurrent bitfields) can be done purely with
conventional arithmetic operations. Normal integers, but not being used normally.

A 32-bit microprocessor (comprised of hardware) can have 32-bit registers that
represent integers that are not signed, or that are signed, both at the same
time. It all depends on what software does to interpret the meaning of those
32-bit register bits. What's the correct interval representation for the
design of the registers in that hardware?

Another case I neglected is also salient. In some very useful encoding
systems, collections of bits can also mean [-1,1] values, which has a
wonderful representation in bit-form, but not as integers, nor as intervals.

Best,
M

On Fri, 6 Mar 2009 08:14:39 -0600, Felton Christopher wrote
> >
> >
> > A collection of bits can well more than a single range in  
> > representation. A
> > 32-bit register can represent 32 bit flags, each having a range  
> > [0,1]. Or it
> > could represent (4) 8-bit values, each having a range [0,255],  
> > [-128,127] or a
> > mix. Or it could represent two fields, (6) 1-bit flag values  
> > concatenated to a
> > 26-bit ordinal. Or, or, or... any number of alternative  
> > representations
> > involving bit-level concurrency that cannot be represented with a  
> > single
> > interval specification. This kind of thing is done all the time in  
> > hardware.
> >
> 
> Think this topic is only discussing when a collection of bits is  
> acting as a number, integer, and not some other "data type" such as  
> flags, logic, etc.  You wouldn't use the min, max when defining a  
> collection of bits that are not used for integer arithmetic.
> 
> I think there will be some different opinions in the design approach 
>  but if you wanted an 8 bit register that was used as simple flags,
>  you  could do that the conventional way without min and max.
> 
> As the essay states in the beginning "essay about elementary  
> arithmetic with integers".  This topic is about representing 
> integers  
> (when the designer intends integers) and not removing basic bit  
> vectors for other uses.
> 
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