1 /*- 2 * Copyright (c) 2004 David Schultz <das@FreeBSD.ORG> 3 * All rights reserved. 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that the following conditions 7 * are met: 8 * 1. Redistributions of source code must retain the above copyright 9 * notice, this list of conditions and the following disclaimer. 10 * 2. Redistributions in binary form must reproduce the above copyright 11 * notice, this list of conditions and the following disclaimer in the 12 * documentation and/or other materials provided with the distribution. 13 * 14 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 15 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 16 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 17 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 18 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 19 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 20 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 21 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 22 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 23 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 24 * SUCH DAMAGE. 25 * 26 * $FreeBSD: head/lib/libc/gen/frexp.c 132366 2004-07-18 21:23:39Z das $ 27 */ 28 29 #include <math.h> 30 31 #include "fpmath.h" 32 33 double 34 frexp(double d, int *ex) 35 { 36 union IEEEd2bits u; 37 38 u.d = d; 39 switch (u.bits.exp) { 40 case 0: /* 0 or subnormal */ 41 if ((u.bits.manl | u.bits.manh) == 0) { 42 *ex = 0; 43 } else { 44 u.d *= 0x1.0p514; 45 *ex = u.bits.exp - 1536; 46 u.bits.exp = 1022; 47 } 48 break; 49 case 2047: /* infinity or NaN; value of *ex is unspecified */ 50 break; 51 default: /* normal */ 52 *ex = u.bits.exp - 1022; 53 u.bits.exp = 1022; 54 break; 55 } 56 return (u.d); 57 } 58