floatdidf.c revision 1.6
11.6Sagc/* $NetBSD: floatdidf.c,v 1.6 2003/08/07 16:43:16 agc Exp $ */ 21.3Scgd 31.1Smycroft/*- 41.1Smycroft * Copyright (c) 1992, 1993 51.1Smycroft * The Regents of the University of California. All rights reserved. 61.1Smycroft * 71.1Smycroft * This software was developed by the Computer Systems Engineering group 81.1Smycroft * at Lawrence Berkeley Laboratory under DARPA contract BG 91-66 and 91.1Smycroft * contributed to Berkeley. 101.1Smycroft * 111.1Smycroft * Redistribution and use in source and binary forms, with or without 121.1Smycroft * modification, are permitted provided that the following conditions 131.1Smycroft * are met: 141.1Smycroft * 1. Redistributions of source code must retain the above copyright 151.1Smycroft * notice, this list of conditions and the following disclaimer. 161.1Smycroft * 2. Redistributions in binary form must reproduce the above copyright 171.1Smycroft * notice, this list of conditions and the following disclaimer in the 181.1Smycroft * documentation and/or other materials provided with the distribution. 191.6Sagc * 3. Neither the name of the University nor the names of its contributors 201.1Smycroft * may be used to endorse or promote products derived from this software 211.1Smycroft * without specific prior written permission. 221.1Smycroft * 231.1Smycroft * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 241.1Smycroft * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 251.1Smycroft * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 261.1Smycroft * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 271.1Smycroft * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 281.1Smycroft * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 291.1Smycroft * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 301.1Smycroft * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 311.1Smycroft * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 321.1Smycroft * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 331.1Smycroft * SUCH DAMAGE. 341.1Smycroft */ 351.1Smycroft 361.4Schristos#include <sys/cdefs.h> 371.1Smycroft#if defined(LIBC_SCCS) && !defined(lint) 381.3Scgd#if 0 391.3Scgdstatic char sccsid[] = "@(#)floatdidf.c 8.1 (Berkeley) 6/4/93"; 401.3Scgd#else 411.6Sagc__RCSID("$NetBSD: floatdidf.c,v 1.6 2003/08/07 16:43:16 agc Exp $"); 421.3Scgd#endif 431.1Smycroft#endif /* LIBC_SCCS and not lint */ 441.1Smycroft 451.1Smycroft#include "quad.h" 461.1Smycroft 471.1Smycroft/* 481.1Smycroft * Convert (signed) quad to double. 491.1Smycroft */ 501.1Smycroftdouble 511.1Smycroft__floatdidf(x) 521.1Smycroft quad_t x; 531.1Smycroft{ 541.1Smycroft double d; 551.1Smycroft union uu u; 561.1Smycroft int neg; 571.1Smycroft 581.1Smycroft /* 591.1Smycroft * Get an unsigned number first, by negating if necessary. 601.1Smycroft */ 611.1Smycroft if (x < 0) 621.1Smycroft u.q = -x, neg = 1; 631.1Smycroft else 641.1Smycroft u.q = x, neg = 0; 651.1Smycroft 661.1Smycroft /* 671.1Smycroft * Now u.ul[H] has the factor of 2^32 (or whatever) and u.ul[L] 681.5Sscw * has the units. Ideally we could just set d, add INT_BITS to 691.1Smycroft * its exponent, and then add the units, but this is portable 701.1Smycroft * code and does not know how to get at an exponent. Machine- 711.1Smycroft * specific code may be able to do this more efficiently. 721.1Smycroft */ 731.5Sscw d = (double)u.ul[H] * (((int)1 << (INT_BITS - 2)) * 4.0); 741.1Smycroft d += u.ul[L]; 751.1Smycroft 761.1Smycroft return (neg ? -d : d); 771.1Smycroft} 78