Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Posting-Version: version B 2.10.2 9/18/84; site brl-tgr.ARPA Path: utzoo!watmath!clyde!burl!ulysses!allegra!mit-eddie!genrad!panda!talcott!harvard!seismo!brl-tgr!ron From: ron@brl-tgr.ARPA (Ron Natalie) Newsgroups: net.lang.c Subject: Re: How does one construct a mask for th Message-ID: <8998@brl-tgr.ARPA> Date: Wed, 6-Mar-85 12:05:14 EST Article-I.D.: brl-tgr.8998 Posted: Wed Mar 6 12:05:14 1985 Date-Received: Fri, 8-Mar-85 03:42:19 EST References: <377@haddock.UUCP> Organization: Ballistic Research Lab Lines: 13 > >> /* > >> This would require generation of a mask for the most significant bit > >> */ > > #define MSB (~(-1>>1)) > Surprise, this doesn't even work on VAX's and PDP -11's. -1>>1 is still -1. Be careful when coming up with ideas like these. C has also been implemented on ones-complement (and subtractive arithmatic) machines. Right shifting of signed quantities is defined to be machine depenedant in C. -Ron