Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP
Path: utzoo!mnetor!uunet!seismo!mimsy!chris
From: chris@mimsy.UUCP (Chris Torek)
Newsgroups: comp.lang.c,comp.unix.wizards
Subject: Vax arithmetic (was Re: pointer alignment)
Message-ID: <7559@mimsy.UUCP>
Date: Thu, 16-Jul-87 10:05:08 EDT
Article-I.D.: mimsy.7559
Posted: Thu Jul 16 10:05:08 1987
Date-Received: Sat, 18-Jul-87 08:35:04 EDT
References: <493@its63b.ed.ac.uk> <6061@brl-smoke.ARPA> <3812@spool.WISC.EDU> <6706@steinmetz.steinmetz.UUCP>
Organization: U of Maryland, Dept. of Computer Science, Coll. Pk., MD 20742
Lines: 15
Xref: mnetor comp.lang.c:3099 comp.unix.wizards:3272

In article <6706@steinmetz.steinmetz.UUCP> davidsen@steinmetz.steinmetz.UUCP
(William E. Davidsen Jr) writes:
>[ I thought you mentioned that the 32 bit size was hardware supported.
>On many machines the short math is faster than long (ie. vax, 68000). ]

On the Vax, the short math is exactly as fast (or as slow) as the
long, at least in register-to-register operations, according to an
ancient set of 780 `timings' that once appeared on the net.  The
4BSD compilers will not put `short' or `char' variables in registers,
and memory references are slower than register references; hence
32 bit arithmetic is often faster than 16 or 8 bit arithmetic on
a Vax.
-- 
In-Real-Life: Chris Torek, Univ of MD Comp Sci Dept (+1 301 454 7690)
Domain:	chris@mimsy.umd.edu	Path:	seismo!mimsy!chris