1 /* $OpenBSD: ieee.h,v 1.4 2012/09/15 15:06:09 martynas Exp $ */ 2 /* 3 * Copyright (c) 1992, 1993 4 * The Regents of the University of California. All rights reserved. 5 * 6 * This software was developed by the Computer Systems Engineering group 7 * at Lawrence Berkeley Laboratory under DARPA contract BG 91-66 and 8 * contributed to Berkeley. 9 * 10 * All advertising materials mentioning features or use of this software 11 * must display the following acknowledgement: 12 * This product includes software developed by the University of 13 * California, Lawrence Berkeley Laboratory. 14 * 15 * Redistribution and use in source and binary forms, with or without 16 * modification, are permitted provided that the following conditions 17 * are met: 18 * 1. Redistributions of source code must retain the above copyright 19 * notice, this list of conditions and the following disclaimer. 20 * 2. Redistributions in binary form must reproduce the above copyright 21 * notice, this list of conditions and the following disclaimer in the 22 * documentation and/or other materials provided with the distribution. 23 * 3. Neither the name of the University nor the names of its contributors 24 * may be used to endorse or promote products derived from this software 25 * without specific prior written permission. 26 * 27 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 28 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 29 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 30 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 31 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 32 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 33 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 34 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 35 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 36 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 37 * SUCH DAMAGE. 38 * 39 * @(#)ieee.h 8.1 (Berkeley) 6/11/93 40 */ 41 42 /* 43 * ieee.h defines the machine-dependent layout of the machine's IEEE 44 * floating point. It does *not* define (yet?) any of the rounding 45 * mode bits, exceptions, and so forth. 46 */ 47 48 /* 49 * Define the number of bits in each fraction and exponent. 50 * 51 * k k+1 52 * Note that 1.0 x 2 == 0.1 x 2 and that denorms are represented 53 * 54 * (-exp_bias+1) 55 * as fractions that look like 0.fffff x 2 . This means that 56 * 57 * -126 58 * the number 0.10000 x 2 , for instance, is the same as the normalized 59 * 60 * -127 -128 61 * float 1.0 x 2 . Thus, to represent 2 , we need one leading zero 62 * 63 * -129 64 * in the fraction; to represent 2 , we need two, and so on. This 65 * 66 * (-exp_bias-fracbits+1) 67 * implies that the smallest denormalized number is 2 68 * 69 * for whichever format we are talking about: for single precision, for 70 * 71 * -126 -149 72 * instance, we get .00000000000000000000001 x 2 , or 1.0 x 2 , and 73 * 74 * -149 == -127 - 23 + 1. 75 */ 76 #define SNG_EXPBITS 8 77 #define SNG_FRACBITS 23 78 79 #define DBL_EXPBITS 11 80 #define DBL_FRACHBITS 20 81 #define DBL_FRACLBITS 32 82 #define DBL_FRACBITS 52 83 84 struct ieee_single { 85 u_int sng_sign:1; 86 u_int sng_exp:8; 87 u_int sng_frac:23; 88 }; 89 90 struct ieee_double { 91 u_int dbl_sign:1; 92 u_int dbl_exp:11; 93 u_int dbl_frach:20; 94 u_int dbl_fracl; 95 }; 96 97 /* 98 * Floats whose exponent is in [1..INFNAN) (of whatever type) are 99 * `normal'. Floats whose exponent is INFNAN are either Inf or NaN. 100 * Floats whose exponent is zero are either zero (iff all fraction 101 * bits are zero) or subnormal values. 102 * 103 * A NaN is a `signalling NaN' if its QUIETNAN bit is clear in its 104 * high fraction; if the bit is set, it is a `quiet NaN'. 105 */ 106 #define SNG_EXP_INFNAN 255 107 #define DBL_EXP_INFNAN 2047 108 109 #if 0 110 #define SNG_QUIETNAN (1 << 22) 111 #define DBL_QUIETNAN (1 << 19) 112 #endif 113 114 /* 115 * Exponent biases. 116 */ 117 #define SNG_EXP_BIAS 127 118 #define DBL_EXP_BIAS 1023 119