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From: gnu@sun.uucp (John Gilmore)
Newsgroups: net.lang.c
Subject: Anybody got a "Hacker's Integer Modulo"?
Message-ID: <418@sun.uucp>
Date: Thu, 12-Jan-84 05:52:10 EST
Article-I.D.: sun.418
Posted: Thu Jan 12 05:52:10 1984
Date-Received: Fri, 13-Jan-84 05:48:53 EST
References: <2208@fortune.UUCP> <3459@utzoo.UUCP>
Organization: Sun Microsystems, Inc.
Lines: 11

With all this talk about division, I'd like to see modulo addressed.  I
looked at compiling "hacker division" last month and came up with the
code already described, but could not come up with reasonable code for
doing "hacker modulo" (given the "Fortran" definition of modulo).

For those who joined late, we're talking about dividing by powers of
two, by shifting -- you have to correct it if the argument is
negative.  For modulo by powers of two, of course, you just want to AND
to keep the low order bits, but again a correction is required for
negatives -- one which was not obvious to me except to brute force it,
which generates lousy code.