1 /* $OpenBSD: floatdisf.c,v 1.6 2005/08/08 08:05:35 espie Exp $ */ 2 /*- 3 * Copyright (c) 1992, 1993 4 * The Regents of the University of California. All rights reserved. 5 * 6 * This software was developed by the Computer Systems Engineering group 7 * at Lawrence Berkeley Laboratory under DARPA contract BG 91-66 and 8 * contributed to Berkeley. 9 * 10 * Redistribution and use in source and binary forms, with or without 11 * modification, are permitted provided that the following conditions 12 * are met: 13 * 1. Redistributions of source code must retain the above copyright 14 * notice, this list of conditions and the following disclaimer. 15 * 2. Redistributions in binary form must reproduce the above copyright 16 * notice, this list of conditions and the following disclaimer in the 17 * documentation and/or other materials provided with the distribution. 18 * 3. Neither the name of the University nor the names of its contributors 19 * may be used to endorse or promote products derived from this software 20 * without specific prior written permission. 21 * 22 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 23 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 24 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 25 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 26 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 27 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 28 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 29 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 30 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 31 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 32 * SUCH DAMAGE. 33 */ 34 35 #include "quad.h" 36 37 /* 38 * Convert (signed) quad to float. 39 */ 40 float 41 __floatdisf(quad_t x) 42 { 43 float f; 44 union uu u; 45 int neg; 46 47 /* 48 * Get an unsigned number first, by negating if necessary. 49 */ 50 if (x < 0) 51 u.q = -x, neg = 1; 52 else 53 u.q = x, neg = 0; 54 55 /* 56 * Now u.ul[H] has the factor of 2^32 (or whatever) and u.ul[L] 57 * has the units. Ideally we could just set f, add INT_BITS to 58 * its exponent, and then add the units, but this is portable 59 * code and does not know how to get at an exponent. Machine- 60 * specific code may be able to do this more efficiently. 61 * 62 * Using double here may be excessive paranoia. 63 */ 64 f = (double)u.ul[H] * (((int)1 << (INT_BITS - 2)) * 4.0); 65 f += u.ul[L]; 66 67 return (neg ? -f : f); 68 } 69