Home | History | Annotate | Download | only in src
      1 /*-
      2  * Copyright (c) 2004-2005 David Schultz <das (at) 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  * $FreeBSD$
     27  */
     28 
     29 #include <float.h>
     30 #include <math.h>
     31 
     32 #include "fpmath.h"
     33 
     34 #if LDBL_MAX_EXP != 0x4000
     35 #error "Unsupported long double format"
     36 #endif
     37 
     38 long double
     39 frexpl(long double x, int *ex)
     40 {
     41 	union IEEEl2bits u;
     42 
     43 	u.e = x;
     44 	switch (u.bits.exp) {
     45 	case 0:		/* 0 or subnormal */
     46 		if ((u.bits.manl | u.bits.manh) == 0) {
     47 			*ex = 0;
     48 		} else {
     49 			u.e *= 0x1.0p514;
     50 			*ex = u.bits.exp - 0x4200;
     51 			u.bits.exp = 0x3ffe;
     52 		}
     53 		break;
     54 	case 0x7fff:	/* infinity or NaN; value of *ex is unspecified */
     55 		break;
     56 	default:	/* normal */
     57 		*ex = u.bits.exp - 0x3ffe;
     58 		u.bits.exp = 0x3ffe;
     59 		break;
     60 	}
     61 	return (u.e);
     62 }
     63