102 lines
3.5 KiB
C
102 lines
3.5 KiB
C
/*-
|
|
* 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: src/lib/msun/src/s_modfl.c,v 1.1 2007/01/07 07:54:21 das Exp $
|
|
*/
|
|
|
|
#include <float.h>
|
|
#include <openlibm_math.h>
|
|
|
|
#include "fpmath.h"
|
|
#include "math_private.h"
|
|
|
|
#if LDBL_MANL_SIZE > 32
|
|
#define MASK ((u_int64_t)-1)
|
|
#else
|
|
#define MASK ((u_int32_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 };
|
|
|
|
OLM_DLLEXPORT 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);
|
|
}
|
|
}
|
|
}
|