Re: Truncating a fixed-point value

[Jacob Sparre Andersen <sparre@nbi.dk>]

Adam Beneschan wrote:

> That will probably work for my purpose; but in general, it's easy to
> define a fixed-point number with a 'Small of 2**(-N) that has more
> bits to the right of the binary point than are available in the
> mantissa part of the floating-point.  If that's the case, this
> approach will fail on certain values (probably M - (K * T'Small) for
> integer M and suitably small integer K).  Since this situation lends
> itself to really efficient code (basically just a bit shift), it's
> kind of a shame that the language doesn't give you a good way to do
> this.

Isn't it possible to write a truncation function, which uses bit shift
when it is appropriate?  If the 'Small is statically known, there is a
fair chance that the compiler will remove the unused branch at
compile-time.

Jacob
-- 
"If we weren't at least occasionally surprised by the results,
 we might as well save ourselves the trouble of measuring :)"