Home | History | Annotate | Line # | Download | only in include
ieee.h revision 1.2 
      1 /*	$NetBSD: ieee.h,v 1.2 2003/08/07 16:28:27 agc Exp $ */
      2 
      3 /*
      4  * Copyright (c) 1992, 1993
      5  *	The Regents of the University of California.  All rights reserved.
      6  *
      7  * This software was developed by the Computer Systems Engineering group
      8  * at Lawrence Berkeley Laboratory under DARPA contract BG 91-66 and
      9  * contributed to Berkeley.
     10  *
     11  * All advertising materials mentioning features or use of this software
     12  * must display the following acknowledgement:
     13  *	This product includes software developed by the University of
     14  *	California, Lawrence Berkeley Laboratory.
     15  *
     16  * Redistribution and use in source and binary forms, with or without
     17  * modification, are permitted provided that the following conditions
     18  * are met:
     19  * 1. Redistributions of source code must retain the above copyright
     20  *    notice, this list of conditions and the following disclaimer.
     21  * 2. Redistributions in binary form must reproduce the above copyright
     22  *    notice, this list of conditions and the following disclaimer in the
     23  *    documentation and/or other materials provided with the distribution.
     24  * 3. Neither the name of the University nor the names of its contributors
     25  *    may be used to endorse or promote products derived from this software
     26  *    without specific prior written permission.
     27  *
     28  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
     29  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     30  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     31  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
     32  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     33  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     34  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     35  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     36  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     37  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     38  * SUCH DAMAGE.
     39  *
     40  *	@(#)ieee.h	8.1 (Berkeley) 6/11/93
     41  */
     42 
     43 /*
     44  * ieee.h defines the machine-dependent layout of the machine's IEEE
     45  * floating point.  It does *not* define (yet?) any of the rounding
     46  * mode bits, exceptions, and so forth.
     47  */
     48 #include <machine/endian.h>
     49 
     50 /*
     51  * Define the number of bits in each fraction and exponent.
     52  *
     53  *		     k	         k+1
     54  * Note that  1.0 x 2  == 0.1 x 2      and that denorms are represented
     55  *
     56  *					  (-exp_bias+1)
     57  * as fractions that look like 0.fffff x 2             .  This means that
     58  *
     59  *			 -126
     60  * the number 0.10000 x 2    , for instance, is the same as the normalized
     61  *
     62  *		-127			   -128
     63  * float 1.0 x 2    .  Thus, to represent 2    , we need one leading zero
     64  *
     65  *				  -129
     66  * in the fraction; to represent 2    , we need two, and so on.  This
     67  *
     68  *						     (-exp_bias-fracbits+1)
     69  * implies that the smallest denormalized number is 2
     70  *
     71  * for whichever format we are talking about: for single precision, for
     72  *
     73  *						-126		-149
     74  * instance, we get .00000000000000000000001 x 2    , or 1.0 x 2    , and
     75  *
     76  * -149 == -127 - 23 + 1.
     77  */
     78 #define	SNG_EXPBITS	8
     79 #define	SNG_FRACBITS	23
     80 
     81 #define	DBL_EXPBITS	11
     82 #define	DBL_FRACBITS	52
     83 
     84 struct ieee_single {
     85 #if BYTE_ORDER == LITTLE_ENDIAN
     86 	u_int	sng_frac:23;
     87 	u_int	sng_exp:8;
     88 	u_int	sng_sign:1;
     89 #else
     90 	u_int	sng_sign:1;
     91 	u_int	sng_exp:8;
     92 	u_int	sng_frac:23;
     93 #endif
     94 };
     95 
     96 struct ieee_double {
     97 #if BYTE_ORDER == LITTLE_ENDIAN
     98 	u_int	dbl_fracl;
     99 	u_int	dbl_frach:20;
    100 	u_int	dbl_exp:11;
    101 	u_int	dbl_sign:1;
    102 #else
    103 	u_int	dbl_sign:1;
    104 	u_int	dbl_exp:11;
    105 	u_int	dbl_frach:20;
    106 	u_int	dbl_fracl;
    107 #endif
    108 };
    109 
    110 /*
    111  * Floats whose exponent is in [1..INFNAN) (of whatever type) are
    112  * `normal'.  Floats whose exponent is INFNAN are either Inf or NaN.
    113  * Floats whose exponent is zero are either zero (iff all fraction
    114  * bits are zero) or subnormal values.
    115  *
    116  * A NaN is a `signalling NaN' if its QUIETNAN bit is clear in its
    117  * high fraction; if the bit is set, it is a `quiet NaN'.
    118  */
    119 #define	SNG_EXP_INFNAN	255
    120 #define	DBL_EXP_INFNAN	2047
    121 
    122 #if 0
    123 #define	SNG_QUIETNAN	(1 << 22)
    124 #define	DBL_QUIETNAN	(1 << 19)
    125 #endif
    126 
    127 /*
    128  * Exponent biases.
    129  */
    130 #define	SNG_EXP_BIAS	127
    131 #define	DBL_EXP_BIAS	1023
    132