1 /** $MirOS: src/sys/sys/ieee754.h,v 1.1 2006/11/03 18:11:08 tg Exp $ */ 2 /* $NetBSD: ieee754.h,v 1.6 2005/12/03 17:10:46 christos Exp $ */ 3 4 /* 5 * Copyright (c) 1992, 1993 6 * The Regents of the University of California. All rights reserved. 7 * 8 * This software was developed by the Computer Systems Engineering group 9 * at Lawrence Berkeley Laboratory under DARPA contract BG 91-66 and 10 * contributed to Berkeley. 11 * 12 * All advertising materials mentioning features or use of this software 13 * must display the following acknowledgement: 14 * This product includes software developed by the University of 15 * California, Lawrence Berkeley Laboratory. 16 * 17 * Redistribution and use in source and binary forms, with or without 18 * modification, are permitted provided that the following conditions 19 * are met: 20 * 1. Redistributions of source code must retain the above copyright 21 * notice, this list of conditions and the following disclaimer. 22 * 2. Redistributions in binary form must reproduce the above copyright 23 * notice, this list of conditions and the following disclaimer in the 24 * documentation and/or other materials provided with the distribution. 25 * 3. Neither the name of the University nor the names of its contributors 26 * may be used to endorse or promote products derived from this software 27 * without specific prior written permission. 28 * 29 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 30 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 31 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 32 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 33 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 34 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 35 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 36 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 37 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 38 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 39 * SUCH DAMAGE. 40 * 41 * @(#)ieee.h 8.1 (Berkeley) 6/11/93 42 */ 43 #ifndef _SYS_IEEE754_H_ 44 #define _SYS_IEEE754_H_ 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 <sys/types.h> 52 #include <machine/endian.h> 53 54 /* 55 * <sys/ieee754.h> defines the layout of IEEE 754 floating point types. 56 * Only single-precision and double-precision types are defined here; 57 * extended types, if available, are defined in the machine-dependent 58 * header. 59 */ 60 61 /* 62 * Define the number of bits in each fraction and exponent. 63 * 64 * k k+1 65 * Note that 1.0 x 2 == 0.1 x 2 and that denorms are represented 66 * 67 * (-exp_bias+1) 68 * as fractions that look like 0.fffff x 2 . This means that 69 * 70 * -126 71 * the number 0.10000 x 2 , for instance, is the same as the normalized 72 * 73 * -127 -128 74 * float 1.0 x 2 . Thus, to represent 2 , we need one leading zero 75 * 76 * -129 77 * in the fraction; to represent 2 , we need two, and so on. This 78 * 79 * (-exp_bias-fracbits+1) 80 * implies that the smallest denormalized number is 2 81 * 82 * for whichever format we are talking about: for single precision, for 83 * 84 * -126 -149 85 * instance, we get .00000000000000000000001 x 2 , or 1.0 x 2 , and 86 * 87 * -149 == -127 - 23 + 1. 88 */ 89 #define SNG_EXPBITS 8 90 #define SNG_FRACBITS 23 91 92 #define DBL_EXPBITS 11 93 #define DBL_FRACBITS 52 94 95 struct ieee_single { 96 #if BYTE_ORDER == BIG_ENDIAN 97 u_int sng_sign:1; 98 u_int sng_exp:8; 99 u_int sng_frac:23; 100 #else 101 u_int sng_frac:23; 102 u_int sng_exp:8; 103 u_int sng_sign:1; 104 #endif 105 }; 106 107 struct ieee_double { 108 #if BYTE_ORDER == BIG_ENDIAN 109 u_int dbl_sign:1; 110 u_int dbl_exp:11; 111 u_int dbl_frach:20; 112 u_int dbl_fracl; 113 #else 114 u_int dbl_fracl; 115 u_int dbl_frach:20; 116 u_int dbl_exp:11; 117 u_int dbl_sign:1; 118 #endif 119 }; 120 121 /* 122 * Floats whose exponent is in [1..INFNAN) (of whatever type) are 123 * `normal'. Floats whose exponent is INFNAN are either Inf or NaN. 124 * Floats whose exponent is zero are either zero (iff all fraction 125 * bits are zero) or subnormal values. 126 * 127 * At least one `signalling NaN' and one `quiet NaN' value must be 128 * implemented. It is left to the architecture to specify how to 129 * distinguish between these. 130 */ 131 #define SNG_EXP_INFNAN 255 132 #define DBL_EXP_INFNAN 2047 133 134 /* 135 * Exponent biases. 136 */ 137 #define SNG_EXP_BIAS 127 138 #define DBL_EXP_BIAS 1023 139 140 /* 141 * Convenience data structures. 142 */ 143 union ieee_single_u { 144 float sngu_f; 145 struct ieee_single sngu_sng; 146 }; 147 148 union ieee_double_u { 149 double dblu_d; 150 struct ieee_double dblu_dbl; 151 }; 152 #endif /* _SYS_IEEE754_H_ */ 153