1 /*- 2 * Copyright (c) 1992, 1993 3 * The Regents of the University of California. All rights reserved. 4 * 5 * This software was developed by the Computer Systems Engineering group 6 * at Lawrence Berkeley Laboratory under DARPA contract BG 91-66 and 7 * contributed to Berkeley. 8 * 9 * Redistribution and use in source and binary forms, with or without 10 * modification, are permitted provided that the following conditions 11 * are met: 12 * 1. Redistributions of source code must retain the above copyright 13 * notice, this list of conditions and the following disclaimer. 14 * 2. Redistributions in binary form must reproduce the above copyright 15 * notice, this list of conditions and the following disclaimer in the 16 * documentation and/or other materials provided with the distribution. 17 * 3. Neither the name of the University nor the names of its contributors 18 * may be used to endorse or promote products derived from this software 19 * without specific prior written permission. 20 * 21 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 22 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 23 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 24 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 25 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 26 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 27 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 28 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 29 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 30 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 31 * SUCH DAMAGE. 32 */ 33 34 #if defined(LIBC_SCCS) && !defined(lint) 35 static char rcsid[] = "$OpenBSD: floatdidf.c,v 1.5 2004/10/17 17:49:21 otto Exp $"; 36 #endif /* LIBC_SCCS and not lint */ 37 38 #include "quad.h" 39 40 /* 41 * Convert (signed) quad to double. 42 */ 43 double 44 __floatdidf(quad_t x) 45 { 46 double d; 47 union uu u; 48 int neg; 49 50 /* 51 * Get an unsigned number first, by negating if necessary. 52 */ 53 if (x < 0) 54 u.q = -x, neg = 1; 55 else 56 u.q = x, neg = 0; 57 58 /* 59 * Now u.ul[H] has the factor of 2^32 (or whatever) and u.ul[L] 60 * has the units. Ideally we could just set d, add INT_BITS to 61 * its exponent, and then add the units, but this is portable 62 * code and does not know how to get at an exponent. Machine- 63 * specific code may be able to do this more efficiently. 64 */ 65 d = (double)u.ul[H] * (((int)1 << (INT_BITS - 2)) * 4.0); 66 d += u.ul[L]; 67 68 return (neg ? -d : d); 69 } 70