96 lines
2.9 KiB
C
96 lines
2.9 KiB
C
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/* $NetBSD: s_rintl.c,v 1.5 2013/08/21 13:04:44 martin Exp $ */
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/*-
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* Copyright (c) 2008 David Schultz <das@FreeBSD.ORG>
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* All rights reserved.
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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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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR 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 AUTHOR 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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#include <sys/cdefs.h>
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#if 0
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__FBSDID("$FreeBSD: src/lib/msun/src/s_rintl.c,v 1.5 2008/02/22 11:59:05 bde Exp $");
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#else
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__RCSID("$NetBSD: s_rintl.c,v 1.5 2013/08/21 13:04:44 martin Exp $");
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#endif
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#include <float.h>
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#include <machine/ieee.h>
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#include "math.h"
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#include "math_private.h"
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#ifdef __HAVE_LONG_DOUBLE
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static const float
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shift[2] = {
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#if EXT_FRACBITS == 64
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0x1.0p63, -0x1.0p63
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#elif EXT_FRACBITS == 113
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0x1.0p112, -0x1.0p112
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#elif EXT_FRACBITS == 112
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0x1.0p111, -0x1.0p111
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#else
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#error "Unsupported long double format"
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#endif
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};
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static const float zero[2] = { 0.0, -0.0 };
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long double
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rintl(long double x)
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{
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union ieee_ext_u u;
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uint32_t expsign;
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int ex, sign;
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u.extu_ld = x;
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u.extu_ext.ext_frach &= ~0x80000000;
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expsign = u.extu_ext.ext_sign;
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ex = expsign & 0x7fff;
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if (ex >= EXT_EXP_BIAS + EXT_FRACBITS - 1) {
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if (ex == EXT_EXP_BIAS + EXT_FRACBITS)
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return (x + x); /* Inf, NaN, or unsupported format */
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return (x); /* finite and already an integer */
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}
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sign = expsign >> 15;
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/*
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* The following code assumes that intermediate results are
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* evaluated in long double precision. If they are evaluated in
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* greater precision, double rounding may occur, and if they are
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* evaluated in less precision (as on i386), results will be
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* wildly incorrect.
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*/
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x += shift[sign];
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x -= shift[sign];
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/*
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* If the result is +-0, then it must have the same sign as x, but
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* the above calculation doesn't always give this. Fix up the sign.
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*/
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if (ex < EXT_EXP_BIAS && x == 0.0L)
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return (zero[sign]);
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return (x);
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}
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#endif
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