halflen.cal

Calc Software Package for Number Calc

/*
 * halflen - determine the length of numeric value in HALFs
 *
 * Copyright (C) 1999,2004  Landon Curt Noll
 *
 * Calc is open software; you can redistribute it and/or modify it under
 * the terms of the version 2.1 of the GNU Lesser General Public License
 * as published by the Free Software Foundation.
 *
 * Calc is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
 * or FITNESS FOR A PARTICULAR PURPOSE.	 See the GNU Lesser General
 * Public License for more details.
 *
 * A copy of version 2.1 of the GNU Lesser General Public License is
 * distributed with calc under the filename COPYING-LGPL.  You should have
 * received a copy with calc; if not, write to Free Software Foundation, Inc.
 * 59 Temple Place, Suite 330, Boston, MA  02111-1307, USA.
 *
 * @(#) $Revision: 29.3 $
 * @(#) $Id: halflen.cal,v 29.3 2004/03/31 05:03:02 chongo Exp $
 * @(#) $Source: /usr/local/src/cmd/calc/custom/RCS/halflen.cal,v $
 *
 * Under source code control:	1997/03/08 20:51:32
 * File existed as early as:	1997
 *
 * chongo <was here> /\oo/\	http://www.isthe.com/chongo/
 * Share and enjoy!  :-)	http://www.isthe.com/chongo/tech/comp/calc/
 */

/*
 * This file is part of the custom sample calc files.
 *
 * NOTE: You must use a calc that was compiled with ALLOW_CUSTOM= -DCUSTOM
 *	 and run with a -C arg.
 */
if (config("compile_custom") == 0) {
	quit "calc compiled without -DCUSTOM";
} else if (config("allow_custom") == 0) {
	quit "calc was run without the -D command line option";
}


define halflen(num)
{
	local baseb;	    /* bit len of a HALF */

	/*
	 * firewall
	 */
	if (!isnum(num)) {
		return newerror("halflen only works on numeric values");
	}

	/*
	 * determine baseb
	 */
	baseb = custom("sysinfo","BASEB");

	/*
	 * determine the HALF length of a numeric value
	 */
	if (num == 0) {
		/* consider 0 to be 1 HALF long */
		return 1;
	} else if (isint(num)) {
		return (highbit(num)+baseb-1)/baseb;
	} else if (isreal(num)) {
		return halflen(num(num)) + halflen(den(num));
	} else if (isnum(num)) {
		return halflen(re(num)) + halflen(im(num));
	} else {
		return newerror("halflen only works on numeric values");
	}
}