1 /* $OpenBSD: ieee.h,v 1.1 2001/09/06 00:07:09 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. All advertising materials mentioning features or use of this software 26 * must display the following acknowledgement: 27 * This product includes software developed by the University of 28 * California, Berkeley and its contributors. 29 * 4. Neither the name of the University nor the names of its contributors 30 * may be used to endorse or promote products derived from this software 31 * without specific prior written permission. 32 * 33 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 34 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 35 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 36 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 37 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 38 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 39 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 40 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 41 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 42 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 43 * SUCH DAMAGE. 44 * 45 * @(#)ieee.h 8.1 (Berkeley) 6/11/93 46 */ 47 48 /* 49 * ieee.h defines the machine-dependent layout of the machine's IEEE 50 * floating point. It does *not* define (yet?) any of the rounding 51 * mode bits, exceptions, and so forth. 52 */ 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 #define EXT_EXPBITS 15 89 #define EXT_FRACBITS 112 90 91 struct ieee_single { 92 u_int sng_frac:23; 93 u_int sng_exp:8; 94 u_int sng_sign:1; 95 }; 96 97 struct ieee_double { 98 u_int dbl_fracl; 99 u_int dbl_frach:20; 100 u_int dbl_exp:11; 101 u_int dbl_sign:1; 102 }; 103 104 struct ieee_ext { 105 u_int ext_fracl; 106 u_int ext_fraclm; 107 u_int ext_frachm; 108 u_int ext_frach:16; 109 u_int ext_exp:15; 110 u_int ext_sign:1; 111 }; 112 113 /* 114 * Floats whose exponent is in [1..INFNAN) (of whatever type) are 115 * `normal'. Floats whose exponent is INFNAN are either Inf or NaN. 116 * Floats whose exponent is zero are either zero (iff all fraction 117 * bits are zero) or subnormal values. 118 * 119 * A NaN is a `signalling NaN' if its QUIETNAN bit is clear in its 120 * high fraction; if the bit is set, it is a `quiet NaN'. 121 */ 122 #define SNG_EXP_INFNAN 255 123 #define DBL_EXP_INFNAN 2047 124 #define EXT_EXP_INFNAN 32767 125 126 #if 0 127 #define SNG_QUIETNAN (1 << 22) 128 #define DBL_QUIETNAN (1 << 19) 129 #define EXT_QUIETNAN (1 << 15) 130 #endif 131 132 /* 133 * Exponent biases. 134 */ 135 #define SNG_EXP_BIAS 127 136 #define DBL_EXP_BIAS 1023 137 #define EXT_EXP_BIAS 16383 138