Annotation of sys/arch/amd64/include/ieee.h, Revision 1.1
1.1 ! nbrk 1: /* $OpenBSD: ieee.h,v 1.1 2004/01/28 01:39:39 mickey 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
CVSweb