Fixed-point

[Jeff Carter <carter@innocon.com>]

Jack Crenshaw's "Programmer's Toolbox" column in *Embedded Systems
Programming* has been discussing implementing multiple precision
integers and fixed-point types in C++ for some time. I was wondering
when he'd address why you'd go to the effort, rather than use a language
with fixed-point type support. In the 1997 Apr issue, he does:

"The designers of Ada ... tried to get too fancy. Instead of restricting
the type to words commensurate with the natural word length of the
computer, they gave us a more general definition that allows for words
of any bit length and any resolution. ... [T]he end result was the same:
fixed-point operations are so slow in Ada that few people bother to use
the type, and many Ada shops prohibit their use as a matter programming
style."

Has anyone encountered this phenomenon? In my experience, with modern
compilers, fixed-point operations are not too slow, especially when
using a binary delta. However, I don't have sufficient amunition to
refute this. Perhaps one (or several) of the more knowlegeable out there
would like to take this on.

The editor-in-chief, Lindsey Vereen, is lvereen@mfi.com. Their web site
is www.embedded.com.
-- 
Jeff Carter
Innovative Concepts, Inc.

Now go away, or I shall taunt you a second time.

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