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      1 /*	$NetBSD: s_frexpl.c,v 1.3 2013/02/12 21:40:19 martin Exp $	*/
      2 
      3 /*-
      4  * Copyright (c) 2004-2005 David Schultz <das (at) 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: src/lib/msun/src/s_frexpl.c,v 1.1 2005/03/07 04:54:51 das Exp $
     29  */
     30 
     31 #include <sys/cdefs.h>
     32 __RCSID("$NetBSD: s_frexpl.c,v 1.3 2013/02/12 21:40:19 martin Exp $");
     33 
     34 #include <machine/ieee.h>
     35 #include <float.h>
     36 #include <math.h>
     37 
     38 #include "math_private.h"
     39 
     40 #ifdef __HAVE_LONG_DOUBLE
     41 #if LDBL_MAX_EXP != 0x4000
     42 #error "Unsupported long double format"
     43 #endif
     44 
     45 long double
     46 frexpl(long double x, int *ex)
     47 {
     48 	union ieee_ext_u u;
     49 
     50 	u.extu_ld = x;
     51 	switch (u.extu_ext.ext_exp) {
     52 	case 0:		/* 0 or subnormal */
     53 		if ((u.extu_ext.ext_fracl | u.extu_ext.ext_frach) == 0) {
     54 			*ex = 0;
     55 		} else {
     56 			u.extu_ld *= 0x1.0p514;
     57 			*ex = u.extu_ext.ext_exp - 0x4200;
     58 			u.extu_ext.ext_exp = 0x3ffe;
     59 		}
     60 		break;
     61 	case 0x7fff:	/* infinity or NaN; value of *ex is unspecified */
     62 		break;
     63 	default:	/* normal */
     64 		*ex = u.extu_ext.ext_exp - 0x3ffe;
     65 		u.extu_ext.ext_exp = 0x3ffe;
     66 		break;
     67 	}
     68 	return (u.extu_ld);
     69 }
     70 #endif
     71