1 /* $OpenBSD: frexp.c,v 1.10 2013/07/03 04:46:36 espie Exp $ */ 2 3 /*- 4 * Copyright (c) 2004 David Schultz <das@FreeBSD.ORG> 5 * All rights reserved. 6 * 7 * Redistribution and use in source and binary forms, with or without 8 * modification, are permitted provided that the following conditions 9 * are met: 10 * 1. Redistributions of source code must retain the above copyright 11 * notice, this list of conditions and the following disclaimer. 12 * 2. Redistributions in binary form must reproduce the above copyright 13 * notice, this list of conditions and the following disclaimer in the 14 * documentation and/or other materials provided with the distribution. 15 * 16 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 17 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 18 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 19 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 20 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 21 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 22 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 23 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 24 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 25 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 26 * SUCH DAMAGE. 27 * 28 * $FreeBSD: frexp.c,v 1.1 2004/07/18 21:23:39 das Exp $ 29 */ 30 31 #include <sys/types.h> 32 #include <machine/ieee.h> 33 #include <float.h> 34 #include <math.h> 35 36 #pragma GCC diagnostic push 37 #pragma GCC diagnostic ignored "-Wmissing-prototypes" 38 39 __asm__(".symver pastfrexp,frexp@DF306.0"); 40 double 41 pastfrexp(double v, int *ex) 42 { 43 union { 44 double v; 45 struct ieee_double s; 46 } u; 47 48 u.v = v; 49 switch (u.s.dbl_exp) { 50 case 0: /* 0 or subnormal */ 51 if ((u.s.dbl_fracl | u.s.dbl_frach) == 0) { 52 *ex = 0; 53 } else { 54 /* 55 * The power of 2 is arbitrary, any value from 54 to 56 * 1024 will do. 57 */ 58 u.v *= 0x1.0p514; 59 *ex = u.s.dbl_exp - (DBL_EXP_BIAS - 1 + 514); 60 u.s.dbl_exp = DBL_EXP_BIAS - 1; 61 } 62 break; 63 case DBL_EXP_INFNAN: /* Inf or NaN; value of *ex is unspecified */ 64 break; 65 default: /* normal */ 66 *ex = u.s.dbl_exp - (DBL_EXP_BIAS - 1); 67 u.s.dbl_exp = DBL_EXP_BIAS - 1; 68 break; 69 } 70 return (u.v); 71 } 72 73 #pragma GCC diagnostic pop 74