| The Android Open Source Project | a27d2ba | 2008-10-21 07:00:00 -0700 | [diff] [blame^] | 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 |