155 lines
4.5 KiB
C
155 lines
4.5 KiB
C
/* $NetBSD: ieee754.h,v 1.4 2003/10/27 02:30:26 simonb Exp $ */
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/*-
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* Copyright (c) 1992, 1993
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* The Regents of the University of California. All rights reserved.
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*
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* This software was developed by the Computer Systems Engineering group
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* at Lawrence Berkeley Laboratory under DARPA contract BG 91-66 and
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* contributed to Berkeley.
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*
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* All advertising materials mentioning features or use of this software
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* must display the following acknowledgement:
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* This product includes software developed by the University of
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* California, Lawrence Berkeley Laboratory.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. Neither the name of the University nor the names of its contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*
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* @(#)ieee.h 8.1 (Berkeley) 6/11/93
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*
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* $FreeBSD$
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*
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*/
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/*
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* NOTICE: This is not a standalone file. To use it, #include it in
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* your port's ieee.h header.
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*/
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#include <machine/endian.h>
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/*
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* <sys/ieee754.h> defines the layout of IEEE 754 floating point types.
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* Only single-precision and double-precision types are defined here;
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* extended types, if available, are defined in the machine-dependent
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* header.
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*/
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/*
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* Define the number of bits in each fraction and exponent.
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*
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* k k+1
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* Note that 1.0 x 2 == 0.1 x 2 and that denorms are represented
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*
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* (-exp_bias+1)
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* as fractions that look like 0.fffff x 2 . This means that
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*
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* -126
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* the number 0.10000 x 2 , for instance, is the same as the normalized
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*
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* -127 -128
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* float 1.0 x 2 . Thus, to represent 2 , we need one leading zero
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*
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* -129
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* in the fraction; to represent 2 , we need two, and so on. This
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*
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* (-exp_bias-fracbits+1)
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* implies that the smallest denormalized number is 2
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*
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* for whichever format we are talking about: for single precision, for
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*
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* -126 -149
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* instance, we get .00000000000000000000001 x 2 , or 1.0 x 2 , and
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*
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* -149 == -127 - 23 + 1.
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*/
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#define SNG_EXPBITS 8
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#define SNG_FRACBITS 23
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#define DBL_EXPBITS 11
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#define DBL_FRACBITS 52
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struct ieee_single {
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#if _BYTE_ORDER == _BIG_ENDIAN
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u_int sng_sign:1;
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u_int sng_exp:8;
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u_int sng_frac:23;
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#else
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u_int sng_frac:23;
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u_int sng_exp:8;
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u_int sng_sign:1;
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#endif
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};
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struct ieee_double {
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#if _BYTE_ORDER == _BIG_ENDIAN
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u_int dbl_sign:1;
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u_int dbl_exp:11;
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u_int dbl_frach:20;
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u_int dbl_fracl;
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#else
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u_int dbl_fracl;
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u_int dbl_frach:20;
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u_int dbl_exp:11;
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u_int dbl_sign:1;
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#endif
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};
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/*
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* Floats whose exponent is in [1..INFNAN) (of whatever type) are
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* `normal'. Floats whose exponent is INFNAN are either Inf or NaN.
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* Floats whose exponent is zero are either zero (iff all fraction
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* bits are zero) or subnormal values.
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*
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* A NaN is a `signalling NaN' if its QUIETNAN bit is clear in its
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* high fraction; if the bit is set, it is a `quiet NaN'.
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*/
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#define SNG_EXP_INFNAN 255
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#define DBL_EXP_INFNAN 2047
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#if 0
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#define SNG_QUIETNAN (1 << 22)
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#define DBL_QUIETNAN (1 << 19)
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#endif
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/*
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* Exponent biases.
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*/
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#define SNG_EXP_BIAS 127
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#define DBL_EXP_BIAS 1023
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/*
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* Convenience data structures.
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*/
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union ieee_single_u {
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float sngu_f;
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struct ieee_single sngu_sng;
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};
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union ieee_double_u {
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double dblu_d;
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struct ieee_double dblu_dbl;
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};
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