hash table types -- ROT

[Glenn S. Burke <GSB@MIT-MC>]

NIL has a ROT function which rotates within a fixnum size.  It was
there years and years ago, and never taken out.  The ONLY use within
all of NIL is hidden inside a macro which combines hash codes, called
SXHASH-COMBINE -- (SXHASH-COMBINE n1 n2 ...) crunches together its
arguments, rotating them varying amounts first.

I can't say i've ever wanted to use ROT in any other circumstance.  I
have on occasion, however, thought about a LDB which sign-extends.