1 /* $OpenBSD: ieee.h,v 1.2 2003/06/02 23:27:47 millert Exp $ */ 2 /* $NetBSD: ieee.h,v 1.1 1996/09/30 16:34:25 ws 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 44 /* 45 * ieee.h defines the machine-dependent layout of the machine's IEEE 46 * floating point. It does *not* define (yet?) any of the rounding 47 * mode bits, exceptions, and so forth. 48 */ 49 50 /* 51 * Define the number of bits in each fraction and exponent. 52 * 53 * k k+1 54 * Note that 1.0 x 2 == 0.1 x 2 and that denorms are represented 55 * 56 * (-exp_bias+1) 57 * as fractions that look like 0.fffff x 2 . This means that 58 * 59 * -126 60 * the number 0.10000 x 2 , for instance, is the same as the normalized 61 * 62 * -127 -128 63 * float 1.0 x 2 . Thus, to represent 2 , we need one leading zero 64 * 65 * -129 66 * in the fraction; to represent 2 , we need two, and so on. This 67 * 68 * (-exp_bias-fracbits+1) 69 * implies that the smallest denormalized number is 2 70 * 71 * for whichever format we are talking about: for single precision, for 72 * 73 * -126 -149 74 * instance, we get .00000000000000000000001 x 2 , or 1.0 x 2 , and 75 * 76 * -149 == -127 - 23 + 1. 77 */ 78 #define SNG_EXPBITS 8 79 #define SNG_FRACBITS 23 80 81 #define DBL_EXPBITS 11 82 #define DBL_FRACBITS 52 83 84 #define EXT_EXPBITS 15 85 #define EXT_FRACBITS 112 86 87 struct ieee_single { 88 u_int sng_frac:23; 89 u_int sng_exp:8; 90 u_int sng_sign:1; 91 }; 92 93 struct ieee_double { 94 u_int dbl_fracl; 95 u_int dbl_frach:20; 96 u_int dbl_exp:11; 97 u_int dbl_sign:1; 98 }; 99 100 struct ieee_ext { 101 u_int ext_fracl; 102 u_int ext_fraclm; 103 u_int ext_frachm; 104 u_int ext_frach:16; 105 u_int ext_exp:15; 106 u_int ext_sign:1; 107 }; 108 109 /* 110 * Floats whose exponent is in [1..INFNAN) (of whatever type) are 111 * `normal'. Floats whose exponent is INFNAN are either Inf or NaN. 112 * Floats whose exponent is zero are either zero (iff all fraction 113 * bits are zero) or subnormal values. 114 * 115 * A NaN is a `signalling NaN' if its QUIETNAN bit is clear in its 116 * high fraction; if the bit is set, it is a `quiet NaN'. 117 */ 118 #define SNG_EXP_INFNAN 255 119 #define DBL_EXP_INFNAN 2047 120 #define EXT_EXP_INFNAN 32767 121 122 #if 0 123 #define SNG_QUIETNAN (1 << 22) 124 #define DBL_QUIETNAN (1 << 19) 125 #define EXT_QUIETNAN (1 << 15) 126 #endif 127 128 /* 129 * Exponent biases. 130 */ 131 #define SNG_EXP_BIAS 127 132 #define DBL_EXP_BIAS 1023 133 #define EXT_EXP_BIAS 16383 134
