1/*	$NetBSD: ieee754.h,v 1.4 2003/10/27 02:30:26 simonb Exp $	*/
  2
  3/*-
  4 * SPDX-License-Identifier: BSD-3-Clause
  5 *
  6 * Copyright (c) 1992, 1993
  7 *	The Regents of the University of California.  All rights reserved.
  8 *
  9 * This software was developed by the Computer Systems Engineering group
 10 * at Lawrence Berkeley Laboratory under DARPA contract BG 91-66 and
 11 * contributed to Berkeley.
 12 *
 13 * All advertising materials mentioning features or use of this software
 14 * must display the following acknowledgement:
 15 *	This product includes software developed by the University of
 16 *	California, Lawrence Berkeley Laboratory.
 17 *
 18 * Redistribution and use in source and binary forms, with or without
 19 * modification, are permitted provided that the following conditions
 20 * are met:
 21 * 1. Redistributions of source code must retain the above copyright
 22 *    notice, this list of conditions and the following disclaimer.
 23 * 2. Redistributions in binary form must reproduce the above copyright
 24 *    notice, this list of conditions and the following disclaimer in the
 25 *    documentation and/or other materials provided with the distribution.
 26 * 3. Neither the name of the University nor the names of its contributors
 27 *    may be used to endorse or promote products derived from this software
 28 *    without specific prior written permission.
 29 *
 30 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 31 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 32 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 33 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 34 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 35 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 36 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 37 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 38 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 39 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 40 * SUCH DAMAGE.
 41 *
 42 *	@(#)ieee.h	8.1 (Berkeley) 6/11/93
 43 *
 44 */
 45
 46/*
 47 * NOTICE: This is not a standalone file.  To use it, #include it in
 48 * your port's ieee.h header.
 49 */
 50
 51#include <machine/endian.h>
 52
 53/*
 54 * <sys/ieee754.h> defines the layout of IEEE 754 floating point types.
 55 * Only single-precision and double-precision types are defined here;
 56 * extended types, if available, are defined in the machine-dependent
 57 * header.
 58 */
 59
 60/*
 61 * Define the number of bits in each fraction and exponent.
 62 *
 63 *		     k	         k+1
 64 * Note that  1.0 x 2  == 0.1 x 2      and that denorms are represented
 65 *
 66 *					  (-exp_bias+1)
 67 * as fractions that look like 0.fffff x 2             .  This means that
 68 *
 69 *			 -126
 70 * the number 0.10000 x 2    , for instance, is the same as the normalized
 71 *
 72 *		-127			   -128
 73 * float 1.0 x 2    .  Thus, to represent 2    , we need one leading zero
 74 *
 75 *				  -129
 76 * in the fraction; to represent 2    , we need two, and so on.  This
 77 *
 78 *						     (-exp_bias-fracbits+1)
 79 * implies that the smallest denormalized number is 2
 80 *
 81 * for whichever format we are talking about: for single precision, for
 82 *
 83 *						-126		-149
 84 * instance, we get .00000000000000000000001 x 2    , or 1.0 x 2    , and
 85 *
 86 * -149 == -127 - 23 + 1.
 87 */
 88#define	SNG_EXPBITS	8
 89#define	SNG_FRACBITS	23
 90
 91#define	DBL_EXPBITS	11
 92#define	DBL_FRACBITS	52
 93
 94#if defined(__VFP_FP__) || defined(__ARM_EABI__)
 95#define	_IEEE_WORD_ORDER	_BYTE_ORDER
 96#else
 97#define	_IEEE_WORD_ORDER	_BIG_ENDIAN
 98#endif
 99
100struct ieee_single {
101#if _BYTE_ORDER == _BIG_ENDIAN
102	u_int	sng_sign:1;
103	u_int	sng_exp:8;
104	u_int	sng_frac:23;
105#else
106	u_int	sng_frac:23;
107	u_int	sng_exp:8;
108	u_int	sng_sign:1;
109#endif
110};
111
112struct ieee_double {
113#if _BYTE_ORDER == _BIG_ENDIAN
114	u_int	dbl_sign:1;
115	u_int	dbl_exp:11;
116	u_int	dbl_frach:20;
117	u_int	dbl_fracl;
118#else
119#if _IEEE_WORD_ORDER == _LITTLE_ENDIAN
120	u_int	dbl_fracl;
121#endif
122	u_int	dbl_frach:20;
123	u_int	dbl_exp:11;
124	u_int	dbl_sign:1;
125#if _IEEE_WORD_ORDER == _BIG_ENDIAN
126	u_int   dbl_fracl;
127#endif
128#endif
129};
130
131/*
132 * Floats whose exponent is in [1..INFNAN) (of whatever type) are
133 * `normal'.  Floats whose exponent is INFNAN are either Inf or NaN.
134 * Floats whose exponent is zero are either zero (iff all fraction
135 * bits are zero) or subnormal values.
136 *
137 * A NaN is a `signalling NaN' if its QUIETNAN bit is clear in its
138 * high fraction; if the bit is set, it is a `quiet NaN'.
139 */
140#define	SNG_EXP_INFNAN	255
141#define	DBL_EXP_INFNAN	2047
142
143#if 0
144#define	SNG_QUIETNAN	(1 << 22)
145#define	DBL_QUIETNAN	(1 << 19)
146#endif
147
148/*
149 * Exponent biases.
150 */
151#define	SNG_EXP_BIAS	127
152#define	DBL_EXP_BIAS	1023
153
154/*
155 * Convenience data structures.
156 */
157union ieee_single_u {
158	float			sngu_f;
159	struct ieee_single	sngu_sng;
160};
161
162union ieee_double_u {
163	double			dblu_d;
164	struct ieee_double	dblu_dbl;
165};