floatdisf.c revision 1573
11573Srgrimes/*- 21573Srgrimes * Copyright (c) 1992, 1993 31573Srgrimes * The Regents of the University of California. All rights reserved. 41573Srgrimes * 51573Srgrimes * This software was developed by the Computer Systems Engineering group 61573Srgrimes * at Lawrence Berkeley Laboratory under DARPA contract BG 91-66 and 71573Srgrimes * contributed to Berkeley. 81573Srgrimes * 91573Srgrimes * Redistribution and use in source and binary forms, with or without 101573Srgrimes * modification, are permitted provided that the following conditions 111573Srgrimes * are met: 121573Srgrimes * 1. Redistributions of source code must retain the above copyright 131573Srgrimes * notice, this list of conditions and the following disclaimer. 141573Srgrimes * 2. Redistributions in binary form must reproduce the above copyright 151573Srgrimes * notice, this list of conditions and the following disclaimer in the 161573Srgrimes * documentation and/or other materials provided with the distribution. 171573Srgrimes * 3. All advertising materials mentioning features or use of this software 181573Srgrimes * must display the following acknowledgement: 191573Srgrimes * This product includes software developed by the University of 201573Srgrimes * California, Berkeley and its contributors. 211573Srgrimes * 4. Neither the name of the University nor the names of its contributors 221573Srgrimes * may be used to endorse or promote products derived from this software 231573Srgrimes * without specific prior written permission. 241573Srgrimes * 251573Srgrimes * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 261573Srgrimes * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 271573Srgrimes * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 281573Srgrimes * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 291573Srgrimes * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 301573Srgrimes * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 311573Srgrimes * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 321573Srgrimes * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 331573Srgrimes * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 341573Srgrimes * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 351573Srgrimes * SUCH DAMAGE. 361573Srgrimes */ 371573Srgrimes 381573Srgrimes#if defined(LIBC_SCCS) && !defined(lint) 391573Srgrimesstatic char sccsid[] = "@(#)floatdisf.c 8.1 (Berkeley) 6/4/93"; 401573Srgrimes#endif /* LIBC_SCCS and not lint */ 411573Srgrimes 421573Srgrimes#include "quad.h" 431573Srgrimes 441573Srgrimes/* 451573Srgrimes * Convert (signed) quad to float. 461573Srgrimes */ 471573Srgrimesfloat 481573Srgrimes__floatdisf(x) 491573Srgrimes quad_t x; 501573Srgrimes{ 511573Srgrimes float f; 521573Srgrimes union uu u; 531573Srgrimes int neg; 541573Srgrimes 551573Srgrimes /* 561573Srgrimes * Get an unsigned number first, by negating if necessary. 571573Srgrimes */ 581573Srgrimes if (x < 0) 591573Srgrimes u.q = -x, neg = 1; 601573Srgrimes else 611573Srgrimes u.q = x, neg = 0; 621573Srgrimes 631573Srgrimes /* 641573Srgrimes * Now u.ul[H] has the factor of 2^32 (or whatever) and u.ul[L] 651573Srgrimes * has the units. Ideally we could just set f, add LONG_BITS to 661573Srgrimes * its exponent, and then add the units, but this is portable 671573Srgrimes * code and does not know how to get at an exponent. Machine- 681573Srgrimes * specific code may be able to do this more efficiently. 691573Srgrimes * 701573Srgrimes * Using double here may be excessive paranoia. 711573Srgrimes */ 721573Srgrimes f = (double)u.ul[H] * ((1 << (LONG_BITS - 2)) * 4.0); 731573Srgrimes f += u.ul[L]; 741573Srgrimes 751573Srgrimes return (neg ? -f : f); 761573Srgrimes} 77