104 lines
3.4 KiB
C
104 lines
3.4 KiB
C
/*-
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* SPDX-License-Identifier: BSD-2-Clause-FreeBSD
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*
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* Copyright (c) 2007 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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* Derived from s_modf.c, which has the following Copyright:
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* ====================================================
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* Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
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*
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* Developed at SunPro, a Sun Microsystems, Inc. business.
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* Permission to use, copy, modify, and distribute this
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* software is freely granted, provided that this notice
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* is preserved.
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* ====================================================
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*
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* $FreeBSD$
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*/
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#include <float.h>
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#include <math.h>
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#include <sys/types.h>
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#include "fpmath.h"
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#if LDBL_MANL_SIZE > 32
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#define MASK ((uint64_t)-1)
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#else
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#define MASK ((uint32_t)-1)
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#endif
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/* Return the last n bits of a word, representing the fractional part. */
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#define GETFRAC(bits, n) ((bits) & ~(MASK << (n)))
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/* The number of fraction bits in manh, not counting the integer bit */
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#define HIBITS (LDBL_MANT_DIG - LDBL_MANL_SIZE)
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static const long double zero[] = { 0.0L, -0.0L };
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long double
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modfl(long double x, long double *iptr)
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{
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union IEEEl2bits ux;
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int e;
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ux.e = x;
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e = ux.bits.exp - LDBL_MAX_EXP + 1;
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if (e < HIBITS) { /* Integer part is in manh. */
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if (e < 0) { /* |x|<1 */
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*iptr = zero[ux.bits.sign];
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return (x);
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} else {
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if ((GETFRAC(ux.bits.manh, HIBITS - 1 - e) |
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ux.bits.manl) == 0) { /* X is an integer. */
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*iptr = x;
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return (zero[ux.bits.sign]);
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} else {
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/* Clear all but the top e+1 bits. */
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ux.bits.manh >>= HIBITS - 1 - e;
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ux.bits.manh <<= HIBITS - 1 - e;
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ux.bits.manl = 0;
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*iptr = ux.e;
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return (x - ux.e);
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}
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}
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} else if (e >= LDBL_MANT_DIG - 1) { /* x has no fraction part. */
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*iptr = x;
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if (x != x) /* Handle NaNs. */
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return (x);
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return (zero[ux.bits.sign]);
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} else { /* Fraction part is in manl. */
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if (GETFRAC(ux.bits.manl, LDBL_MANT_DIG - 1 - e) == 0) {
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/* x is integral. */
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*iptr = x;
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return (zero[ux.bits.sign]);
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} else {
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/* Clear all but the top e+1 bits. */
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ux.bits.manl >>= LDBL_MANT_DIG - 1 - e;
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ux.bits.manl <<= LDBL_MANT_DIG - 1 - e;
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*iptr = ux.e;
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return (x - ux.e);
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}
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}
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}
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