1 /* $NetBSD: ieee754.h,v 1.6.24.1 2007/05/07 19:49:10 pavel 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 #ifndef _SYS_IEEE754_H_ 43 #define _SYS_IEEE754_H_ 44 45 /* 46 * NOTICE: This is not a standalone file. To use it, #include it in 47 * your port's ieee.h header. 48 */ 49 50 #include <machine/endian.h> 51 52 /* 53 * <sys/ieee754.h> defines the layout of IEEE 754 floating point types. 54 * Only single-precision and double-precision types are defined here; 55 * extended types, if available, are defined in the machine-dependent 56 * header. 57 */ 58 59 /* 60 * Define the number of bits in each fraction and exponent. 61 * 62 * k k+1 63 * Note that 1.0 x 2 == 0.1 x 2 and that denorms are represented 64 * 65 * (-exp_bias+1) 66 * as fractions that look like 0.fffff x 2 . This means that 67 * 68 * -126 69 * the number 0.10000 x 2 , for instance, is the same as the normalized 70 * 71 * -127 -128 72 * float 1.0 x 2 . Thus, to represent 2 , we need one leading zero 73 * 74 * -129 75 * in the fraction; to represent 2 , we need two, and so on. This 76 * 77 * (-exp_bias-fracbits+1) 78 * implies that the smallest denormalized number is 2 79 * 80 * for whichever format we are talking about: for single precision, for 81 * 82 * -126 -149 83 * instance, we get .00000000000000000000001 x 2 , or 1.0 x 2 , and 84 * 85 * -149 == -127 - 23 + 1. 86 */ 87 #define SNG_EXPBITS 8 88 #define SNG_FRACBITS 23 89 90 struct ieee_single { 91 #if _BYTE_ORDER == _BIG_ENDIAN 92 u_int sng_sign:1; 93 u_int sng_exp:SNG_EXPBITS; 94 u_int sng_frac:SNG_FRACBITS; 95 #else 96 u_int sng_frac:SNG_FRACBITS; 97 u_int sng_exp:SNG_EXPBITS; 98 u_int sng_sign:1; 99 #endif 100 }; 101 102 #define DBL_EXPBITS 11 103 #define DBL_FRACHBITS 20 104 #define DBL_FRACLBITS 32 105 #define DBL_FRACBITS (DBL_FRACHBITS + DBL_FRACLBITS) 106 107 struct ieee_double { 108 #if _BYTE_ORDER == _BIG_ENDIAN 109 u_int dbl_sign:1; 110 u_int dbl_exp:DBL_EXPBITS; 111 u_int dbl_frach:DBL_FRACHBITS; 112 u_int dbl_fracl:DBL_FRACLBITS; 113 #else 114 u_int dbl_fracl:DBL_FRACLBITS; 115 u_int dbl_frach:DBL_FRACHBITS; 116 u_int dbl_exp:DBL_EXPBITS; 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