1 /* $NetBSD: ieee.h,v 1.1 1996/09/30 16:34:25 ws 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 53 /* 54 * Define the number of bits in each fraction and exponent. 55 * 56 * k k+1 57 * Note that 1.0 x 2 == 0.1 x 2 and that denorms are represented 58 * 59 * (-exp_bias+1) 60 * as fractions that look like 0.fffff x 2 . This means that 61 * 62 * -126 63 * the number 0.10000 x 2 , for instance, is the same as the normalized 64 * 65 * -127 -128 66 * float 1.0 x 2 . Thus, to represent 2 , we need one leading zero 67 * 68 * -129 69 * in the fraction; to represent 2 , we need two, and so on. This 70 * 71 * (-exp_bias-fracbits+1) 72 * implies that the smallest denormalized number is 2 73 * 74 * for whichever format we are talking about: for single precision, for 75 * 76 * -126 -149 77 * instance, we get .00000000000000000000001 x 2 , or 1.0 x 2 , and 78 * 79 * -149 == -127 - 23 + 1. 80 */ 81 #define SNG_EXPBITS 8 82 #define SNG_FRACBITS 23 83 84 #define DBL_EXPBITS 11 85 #define DBL_FRACBITS 52 86 87 #define EXT_EXPBITS 15 88 #define EXT_FRACBITS 112 89 90 struct ieee_single { 91 u_int sng_sign:1; 92 u_int sng_exp:8; 93 u_int sng_frac:23; 94 }; 95 96 struct ieee_double { 97 u_int dbl_sign:1; 98 u_int dbl_exp:11; 99 u_int dbl_frach:20; 100 u_int dbl_fracl; 101 }; 102 103 struct ieee_ext { 104 u_int ext_sign:1; 105 u_int ext_exp:15; 106 u_int ext_frach:16; 107 u_int ext_frachm; 108 u_int ext_fraclm; 109 u_int ext_fracl; 110 }; 111 112 /* 113 * Floats whose exponent is in [1..INFNAN) (of whatever type) are 114 * `normal'. Floats whose exponent is INFNAN are either Inf or NaN. 115 * Floats whose exponent is zero are either zero (iff all fraction 116 * bits are zero) or subnormal values. 117 * 118 * A NaN is a `signalling NaN' if its QUIETNAN bit is clear in its 119 * high fraction; if the bit is set, it is a `quiet NaN'. 120 */ 121 #define SNG_EXP_INFNAN 255 122 #define DBL_EXP_INFNAN 2047 123 #define EXT_EXP_INFNAN 32767 124 125 #if 0 126 #define SNG_QUIETNAN (1 << 22) 127 #define DBL_QUIETNAN (1 << 19) 128 #define EXT_QUIETNAN (1 << 15) 129 #endif 130 131 /* 132 * Exponent biases. 133 */ 134 #define SNG_EXP_BIAS 127 135 #define DBL_EXP_BIAS 1023 136 #define EXT_EXP_BIAS 16383 137