1 /* $NetBSD: floatdidf.c,v 1.5 2002/10/20 10:15:47 scw Exp $ */ 2 3 /*- 4 * Copyright (c) 1992, 1993 5 * The Regents of the University of California. All rights reserved. 6 * 7 * This software was developed by the Computer Systems Engineering group 8 * at Lawrence Berkeley Laboratory under DARPA contract BG 91-66 and 9 * contributed to Berkeley. 10 * 11 * Redistribution and use in source and binary forms, with or without 12 * modification, are permitted provided that the following conditions 13 * are met: 14 * 1. Redistributions of source code must retain the above copyright 15 * notice, this list of conditions and the following disclaimer. 16 * 2. Redistributions in binary form must reproduce the above copyright 17 * notice, this list of conditions and the following disclaimer in the 18 * documentation and/or other materials provided with the distribution. 19 * 3. All advertising materials mentioning features or use of this software 20 * must display the following acknowledgement: 21 * This product includes software developed by the University of 22 * California, Berkeley and its contributors. 23 * 4. Neither the name of the University nor the names of its contributors 24 * may be used to endorse or promote products derived from this software 25 * without specific prior written permission. 26 * 27 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 28 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 29 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 30 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 31 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 32 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 33 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 34 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 35 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 36 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 37 * SUCH DAMAGE. 38 */ 39 40 #include <sys/cdefs.h> 41 #if defined(LIBC_SCCS) && !defined(lint) 42 #if 0 43 static char sccsid[] = "@(#)floatdidf.c 8.1 (Berkeley) 6/4/93"; 44 #else 45 __RCSID("$NetBSD: floatdidf.c,v 1.5 2002/10/20 10:15:47 scw Exp $"); 46 #endif 47 #endif /* LIBC_SCCS and not lint */ 48 49 #include "quad.h" 50 51 /* 52 * Convert (signed) quad to double. 53 */ 54 double 55 __floatdidf(x) 56 quad_t x; 57 { 58 double d; 59 union uu u; 60 int neg; 61 62 /* 63 * Get an unsigned number first, by negating if necessary. 64 */ 65 if (x < 0) 66 u.q = -x, neg = 1; 67 else 68 u.q = x, neg = 0; 69 70 /* 71 * Now u.ul[H] has the factor of 2^32 (or whatever) and u.ul[L] 72 * has the units. Ideally we could just set d, add INT_BITS to 73 * its exponent, and then add the units, but this is portable 74 * code and does not know how to get at an exponent. Machine- 75 * specific code may be able to do this more efficiently. 76 */ 77 d = (double)u.ul[H] * (((int)1 << (INT_BITS - 2)) * 4.0); 78 d += u.ul[L]; 79 80 return (neg ? -d : d); 81 } 82