floatdidf.c revision 1.1
11.1Smycroft/*- 21.1Smycroft * Copyright (c) 1992, 1993 31.1Smycroft * The Regents of the University of California. All rights reserved. 41.1Smycroft * 51.1Smycroft * This software was developed by the Computer Systems Engineering group 61.1Smycroft * at Lawrence Berkeley Laboratory under DARPA contract BG 91-66 and 71.1Smycroft * contributed to Berkeley. 81.1Smycroft * 91.1Smycroft * Redistribution and use in source and binary forms, with or without 101.1Smycroft * modification, are permitted provided that the following conditions 111.1Smycroft * are met: 121.1Smycroft * 1. Redistributions of source code must retain the above copyright 131.1Smycroft * notice, this list of conditions and the following disclaimer. 141.1Smycroft * 2. Redistributions in binary form must reproduce the above copyright 151.1Smycroft * notice, this list of conditions and the following disclaimer in the 161.1Smycroft * documentation and/or other materials provided with the distribution. 171.1Smycroft * 3. All advertising materials mentioning features or use of this software 181.1Smycroft * must display the following acknowledgement: 191.1Smycroft * This product includes software developed by the University of 201.1Smycroft * California, Berkeley and its contributors. 211.1Smycroft * 4. Neither the name of the University nor the names of its contributors 221.1Smycroft * may be used to endorse or promote products derived from this software 231.1Smycroft * without specific prior written permission. 241.1Smycroft * 251.1Smycroft * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 261.1Smycroft * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 271.1Smycroft * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 281.1Smycroft * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 291.1Smycroft * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 301.1Smycroft * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 311.1Smycroft * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 321.1Smycroft * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 331.1Smycroft * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 341.1Smycroft * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 351.1Smycroft * SUCH DAMAGE. 361.1Smycroft */ 371.1Smycroft 381.1Smycroft#if defined(LIBC_SCCS) && !defined(lint) 391.1Smycroft/*static char *sccsid = "from: @(#)floatdidf.c 8.1 (Berkeley) 6/4/93";*/ 401.1Smycroftstatic char *rcsid = "$Id: floatdidf.c,v 1.1 1993/09/16 06:05:58 mycroft Exp $"; 411.1Smycroft#endif /* LIBC_SCCS and not lint */ 421.1Smycroft 431.1Smycroft#include "quad.h" 441.1Smycroft 451.1Smycroft/* 461.1Smycroft * Convert (signed) quad to double. 471.1Smycroft */ 481.1Smycroftdouble 491.1Smycroft__floatdidf(x) 501.1Smycroft quad_t x; 511.1Smycroft{ 521.1Smycroft double d; 531.1Smycroft union uu u; 541.1Smycroft int neg; 551.1Smycroft 561.1Smycroft /* 571.1Smycroft * Get an unsigned number first, by negating if necessary. 581.1Smycroft */ 591.1Smycroft if (x < 0) 601.1Smycroft u.q = -x, neg = 1; 611.1Smycroft else 621.1Smycroft u.q = x, neg = 0; 631.1Smycroft 641.1Smycroft /* 651.1Smycroft * Now u.ul[H] has the factor of 2^32 (or whatever) and u.ul[L] 661.1Smycroft * has the units. Ideally we could just set d, add LONG_BITS to 671.1Smycroft * its exponent, and then add the units, but this is portable 681.1Smycroft * code and does not know how to get at an exponent. Machine- 691.1Smycroft * specific code may be able to do this more efficiently. 701.1Smycroft */ 711.1Smycroft d = (double)u.ul[H] * ((1 << (LONG_BITS - 2)) * 4.0); 721.1Smycroft d += u.ul[L]; 731.1Smycroft 741.1Smycroft return (neg ? -d : d); 751.1Smycroft} 76