🚀 go-pugleaf

In article <9596@cognos.UUCP> jimp@cognos.UUCP (Jim Patterson) writes:
]The problem with this is that the compiler rarely has enough
]information to determine if it's "safe" to just bump the exponent.
]Therefore it's left with the choice of doing a number of runtime
]checks (is f equal to zero? Is exponent already at upper limit?), or
]just punting and generating the naive "multiply by 2.0" instruction.

Of course, if your compiler includes the library support for it, it
COULD do a table lookup to find the new exponent, or to find that it
needs to do a real multiply.  Similarly, this is usually the
fastest way to do bit-twiddling operations without (or even with)
special machine ops.  Sure, with a PDP-11 you didn't want to waste
2K or 4K for a table, but on a 4MB machine with shared libraries it's cheap.
-- 
				Pray for peace;		  Bill
# Bill Stewart 908-949-0705 erebus.att.com!wcs AT&T Bell Labs 4M-312 Holmdel NJ
# I never wanted to be a hacker!  I wanted to be --- a lumberjack!