1 /* $NetBSD: ieee.h,v 1.1 1999/08/29 18:21:20 mycroft 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. All advertising materials mentioning features or use of this software 25 * must display the following acknowledgement: 26 * This product includes software developed by the University of 27 * California, Berkeley and its contributors. 28 * 4. Neither the name of the University nor the names of its contributors 29 * may be used to endorse or promote products derived from this software 30 * without specific prior written permission. 31 * 32 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 33 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 34 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 35 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 36 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 37 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 38 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 39 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 40 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 41 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 42 * SUCH DAMAGE. 43 * 44 * @(#)ieee.h 8.1 (Berkeley) 6/11/93 45 */ 46 47 /* 48 * ieee.h defines the machine-dependent layout of the machine's IEEE 49 * floating point. It does *not* define (yet?) any of the rounding 50 * mode bits, exceptions, and so forth. 51 */ 52 #include <machine/endian.h> 53 54 /* 55 * Define the number of bits in each fraction and exponent. 56 * 57 * k k+1 58 * Note that 1.0 x 2 == 0.1 x 2 and that denorms are represented 59 * 60 * (-exp_bias+1) 61 * as fractions that look like 0.fffff x 2 . This means that 62 * 63 * -126 64 * the number 0.10000 x 2 , for instance, is the same as the normalized 65 * 66 * -127 -128 67 * float 1.0 x 2 . Thus, to represent 2 , we need one leading zero 68 * 69 * -129 70 * in the fraction; to represent 2 , we need two, and so on. This 71 * 72 * (-exp_bias-fracbits+1) 73 * implies that the smallest denormalized number is 2 74 * 75 * for whichever format we are talking about: for single precision, for 76 * 77 * -126 -149 78 * instance, we get .00000000000000000000001 x 2 , or 1.0 x 2 , and 79 * 80 * -149 == -127 - 23 + 1. 81 */ 82 #define SNG_EXPBITS 8 83 #define SNG_FRACBITS 23 84 85 #define DBL_EXPBITS 11 86 #define DBL_FRACBITS 52 87 88 struct ieee_single { 89 #if BYTE_ORDER == LITTLE_ENDIAN 90 u_int sng_frac:23; 91 u_int sng_exp:8; 92 u_int sng_sign:1; 93 #else 94 u_int sng_sign:1; 95 u_int sng_exp:8; 96 u_int sng_frac:23; 97 #endif 98 }; 99 100 struct ieee_double { 101 #if BYTE_ORDER == LITTLE_ENDIAN 102 u_int dbl_fracl; 103 u_int dbl_frach:20; 104 u_int dbl_exp:11; 105 u_int dbl_sign:1; 106 #else 107 u_int dbl_sign:1; 108 u_int dbl_exp:11; 109 u_int dbl_frach:20; 110 u_int dbl_fracl; 111 #endif 112 }; 113 114 /* 115 * Floats whose exponent is in [1..INFNAN) (of whatever type) are 116 * `normal'. Floats whose exponent is INFNAN are either Inf or NaN. 117 * Floats whose exponent is zero are either zero (iff all fraction 118 * bits are zero) or subnormal values. 119 * 120 * A NaN is a `signalling NaN' if its QUIETNAN bit is clear in its 121 * high fraction; if the bit is set, it is a `quiet NaN'. 122 */ 123 #define SNG_EXP_INFNAN 255 124 #define DBL_EXP_INFNAN 2047 125 126 #if 0 127 #define SNG_QUIETNAN (1 << 22) 128 #define DBL_QUIETNAN (1 << 19) 129 #endif 130 131 /* 132 * Exponent biases. 133 */ 134 #define SNG_EXP_BIAS 127 135 #define DBL_EXP_BIAS 1023 136