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 * $FreeBSD$ 45 * 46 */ 47 48 /* 49 * NOTICE: This is not a standalone file. To use it, #include it in 50 * your port's ieee.h header. 51 */ 52 53 #include <machine/endian.h> 54 55 /* 56 * <sys/ieee754.h> defines the layout of IEEE 754 floating point types. 57 * Only single-precision and double-precision types are defined here; 58 * extended types, if available, are defined in the machine-dependent 59 * header. 60 */ 61 62 /* 63 * Define the number of bits in each fraction and exponent. 64 * 65 * k k+1 66 * Note that 1.0 x 2 == 0.1 x 2 and that denorms are represented 67 * 68 * (-exp_bias+1) 69 * as fractions that look like 0.fffff x 2 . This means that 70 * 71 * -126 72 * the number 0.10000 x 2 , for instance, is the same as the normalized 73 * 74 * -127 -128 75 * float 1.0 x 2 . Thus, to represent 2 , we need one leading zero 76 * 77 * -129 78 * in the fraction; to represent 2 , we need two, and so on. This 79 * 80 * (-exp_bias-fracbits+1) 81 * implies that the smallest denormalized number is 2 82 * 83 * for whichever format we are talking about: for single precision, for 84 * 85 * -126 -149 86 * instance, we get .00000000000000000000001 x 2 , or 1.0 x 2 , and 87 * 88 * -149 == -127 - 23 + 1. 89 */ 90 #define SNG_EXPBITS 8 91 #define SNG_FRACBITS 23 92 93 #define DBL_EXPBITS 11 94 #define DBL_FRACBITS 52 95 96 struct ieee_single { 97 #if _BYTE_ORDER == _BIG_ENDIAN 98 u_int sng_sign:1; 99 u_int sng_exp:8; 100 u_int sng_frac:23; 101 #else 102 u_int sng_frac:23; 103 u_int sng_exp:8; 104 u_int sng_sign:1; 105 #endif 106 }; 107 108 struct ieee_double { 109 #if _BYTE_ORDER == _BIG_ENDIAN 110 u_int dbl_sign:1; 111 u_int dbl_exp:11; 112 u_int dbl_frach:20; 113 u_int dbl_fracl; 114 #else 115 u_int dbl_fracl; 116 u_int dbl_frach:20; 117 u_int dbl_exp:11; 118 u_int dbl_sign:1; 119 #endif 120 }; 121 122 /* 123 * Floats whose exponent is in [1..INFNAN) (of whatever type) are 124 * `normal'. Floats whose exponent is INFNAN are either Inf or NaN. 125 * Floats whose exponent is zero are either zero (iff all fraction 126 * bits are zero) or subnormal values. 127 * 128 * A NaN is a `signalling NaN' if its QUIETNAN bit is clear in its 129 * high fraction; if the bit is set, it is a `quiet NaN'. 130 */ 131 #define SNG_EXP_INFNAN 255 132 #define DBL_EXP_INFNAN 2047 133 134 #if 0 135 #define SNG_QUIETNAN (1 << 22) 136 #define DBL_QUIETNAN (1 << 19) 137 #endif 138 139 /* 140 * Exponent biases. 141 */ 142 #define SNG_EXP_BIAS 127 143 #define DBL_EXP_BIAS 1023 144 145 /* 146 * Convenience data structures. 147 */ 148 union ieee_single_u { 149 float sngu_f; 150 struct ieee_single sngu_sng; 151 }; 152 153 union ieee_double_u { 154 double dblu_d; 155 struct ieee_double dblu_dbl; 156 }; 157