1 /* $OpenBSD: ieee.h,v 1.5 2008/09/07 20:36:07 martynas 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 43 /* 44 * ieee.h defines the machine-dependent layout of the machine's IEEE 45 * floating point. It does *not* define (yet?) any of the rounding 46 * mode bits, exceptions, and so forth. 47 */ 48 49 /* 50 * Define the number of bits in each fraction and exponent. 51 * 52 * k k+1 53 * Note that 1.0 x 2 == 0.1 x 2 and that denorms are represented 54 * 55 * (-exp_bias+1) 56 * as fractions that look like 0.fffff x 2 . This means that 57 * 58 * -126 59 * the number 0.10000 x 2 , for instance, is the same as the normalized 60 * 61 * -127 -128 62 * float 1.0 x 2 . Thus, to represent 2 , we need one leading zero 63 * 64 * -129 65 * in the fraction; to represent 2 , we need two, and so on. This 66 * 67 * (-exp_bias-fracbits+1) 68 * implies that the smallest denormalized number is 2 69 * 70 * for whichever format we are talking about: for single precision, for 71 * 72 * -126 -149 73 * instance, we get .00000000000000000000001 x 2 , or 1.0 x 2 , and 74 * 75 * -149 == -127 - 23 + 1. 76 */ 77 #define SNG_EXPBITS 8 78 #define SNG_FRACBITS 23 79 80 #define DBL_EXPBITS 11 81 #define DBL_FRACHBITS 20 82 #define DBL_FRACLBITS 32 83 #define DBL_FRACBITS 52 84 85 struct ieee_single { 86 u_int sng_sign:1; 87 u_int sng_exp:8; 88 u_int sng_frac:23; 89 }; 90 91 struct ieee_double { 92 u_int dbl_sign:1; 93 u_int dbl_exp:11; 94 u_int dbl_frach:20; 95 u_int dbl_fracl; 96 }; 97 98 /* 99 * Floats whose exponent is in [1..INFNAN) (of whatever type) are 100 * `normal'. Floats whose exponent is INFNAN are either Inf or NaN. 101 * Floats whose exponent is zero are either zero (iff all fraction 102 * bits are zero) or subnormal values. 103 * 104 * A NaN is a `signalling NaN' if its QUIETNAN bit is clear in its 105 * high fraction; if the bit is set, it is a `quiet NaN'. 106 */ 107 #define SNG_EXP_INFNAN 255 108 #define DBL_EXP_INFNAN 2047 109 110 #if 0 111 #define SNG_QUIETNAN (1 << 22) 112 #define DBL_QUIETNAN (1 << 19) 113 #endif 114 115 /* 116 * Exponent biases. 117 */ 118 #define SNG_EXP_BIAS 127 119 #define DBL_EXP_BIAS 1023 120