1 /* $NetBSD: ieee754.h,v 1.4 2003/10/27 02:30:26 simonb 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 * $FreeBSD$ 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__) 95 #define _IEEE_WORD_ORDER _BYTE_ORDER 96 #else 97 #define _IEEE_WORD_ORDER _BIG_ENDIAN 98 #endif 99 100 struct 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 }; 111 112 struct 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 */ 157 union ieee_single_u { 158 float sngu_f; 159 struct ieee_single sngu_sng; 160 }; 161 162 union ieee_double_u { 163 double dblu_d; 164 struct ieee_double dblu_dbl; 165 }; 166