1 /* $OpenBSD: ieee.h,v 1.5 2008/09/07 20:36:06 martynas Exp $ */ 2 /* $NetBSD: ieee.h,v 1.1 1995/02/13 23:07:40 cgd 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 * from: Header: ieee.h,v 1.7 92/11/26 02:04:37 torek Exp 44 */ 45 46 /* 47 * ieee.h defines the machine-dependent layout of the machine's IEEE 48 * floating point. It does *not* define (yet?) any of the rounding 49 * mode bits, exceptions, and so forth. 50 */ 51 52 /* 53 * Define the number of bits in each fraction and exponent. 54 * 55 * k k+1 56 * Note that 1.0 x 2 == 0.1 x 2 and that denorms are represented 57 * 58 * (-exp_bias+1) 59 * as fractions that look like 0.fffff x 2 . This means that 60 * 61 * -126 62 * the number 0.10000 x 2 , for instance, is the same as the normalized 63 * 64 * -127 -128 65 * float 1.0 x 2 . Thus, to represent 2 , we need one leading zero 66 * 67 * -129 68 * in the fraction; to represent 2 , we need two, and so on. This 69 * 70 * (-exp_bias-fracbits+1) 71 * implies that the smallest denormalized number is 2 72 * 73 * for whichever format we are talking about: for single precision, for 74 * 75 * -126 -149 76 * instance, we get .00000000000000000000001 x 2 , or 1.0 x 2 , and 77 * 78 * -149 == -127 - 23 + 1. 79 */ 80 #define SNG_EXPBITS 8 81 #define SNG_FRACBITS 23 82 83 #define DBL_EXPBITS 11 84 #define DBL_FRACHBITS 20 85 #define DBL_FRACLBITS 32 86 #define DBL_FRACBITS 52 87 88 struct ieee_single { 89 u_int sng_frac:23; 90 u_int sng_exp:8; 91 u_int sng_sign:1; 92 }; 93 94 struct ieee_double { 95 u_int dbl_fracl; 96 u_int dbl_frach:20; 97 u_int dbl_exp:11; 98 u_int dbl_sign:1; 99 }; 100 101 /* 102 * Floats whose exponent is in [1..INFNAN) (of whatever type) are 103 * `normal'. Floats whose exponent is INFNAN are either Inf or NaN. 104 * Floats whose exponent is zero are either zero (iff all fraction 105 * bits are zero) or subnormal values. 106 * 107 * A NaN is a `signalling NaN' if its QUIETNAN bit is clear in its 108 * high fraction; if the bit is set, it is a `quiet NaN'. 109 */ 110 #define SNG_EXP_INFNAN 255 111 #define DBL_EXP_INFNAN 2047 112 113 #if 0 114 #define SNG_QUIETNAN (1 << 22) 115 #define DBL_QUIETNAN (1 << 19) 116 #endif 117 118 /* 119 * Exponent biases. 120 */ 121 #define SNG_EXP_BIAS 127 122 #define DBL_EXP_BIAS 1023 123