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/*-
* Copyright (c) 2007 David Schultz <das@FreeBSD.ORG>
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*
* Derived from s_modf.c, which has the following Copyright:
* ====================================================
* Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
*
* Developed at SunPro, a Sun Microsystems, Inc. business.
* Permission to use, copy, modify, and distribute this
* software is freely granted, provided that this notice
* is preserved.
* ====================================================
*
* $FreeBSD$
*/
#include <float.h>
#include <math.h>
#include <sys/types.h>
#include "fpmath.h"
#if LDBL_MANL_SIZE > 32
#define MASK ((uint64_t)-1)
#else
#define MASK ((uint32_t)-1)
#endif
/* Return the last n bits of a word, representing the fractional part. */
#define GETFRAC(bits, n) ((bits) & ~(MASK << (n)))
/* The number of fraction bits in manh, not counting the integer bit */
#define HIBITS (LDBL_MANT_DIG - LDBL_MANL_SIZE)
static const long double zero[] = { 0.0L, -0.0L };
long double
modfl(long double x, long double *iptr)
{
union IEEEl2bits ux;
int e;
ux.e = x;
e = ux.bits.exp - LDBL_MAX_EXP + 1;
if (e < HIBITS) { /* Integer part is in manh. */
if (e < 0) { /* |x|<1 */
*iptr = zero[ux.bits.sign];
return (x);
} else {
if ((GETFRAC(ux.bits.manh, HIBITS - 1 - e) |
ux.bits.manl) == 0) { /* X is an integer. */
*iptr = x;
return (zero[ux.bits.sign]);
} else {
/* Clear all but the top e+1 bits. */
ux.bits.manh >>= HIBITS - 1 - e;
ux.bits.manh <<= HIBITS - 1 - e;
ux.bits.manl = 0;
*iptr = ux.e;
return (x - ux.e);
}
}
} else if (e >= LDBL_MANT_DIG - 1) { /* x has no fraction part. */
*iptr = x;
if (x != x) /* Handle NaNs. */
return (x);
return (zero[ux.bits.sign]);
} else { /* Fraction part is in manl. */
if (GETFRAC(ux.bits.manl, LDBL_MANT_DIG - 1 - e) == 0) {
/* x is integral. */
*iptr = x;
return (zero[ux.bits.sign]);
} else {
/* Clear all but the top e+1 bits. */
ux.bits.manl >>= LDBL_MANT_DIG - 1 - e;
ux.bits.manl <<= LDBL_MANT_DIG - 1 - e;
*iptr = ux.e;
return (x - ux.e);
}
}
}
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