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/* s_modfl.c -- long double version of s_modf.c.
*/
/*
* ====================================================
* 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.
* ====================================================
*/
#if defined(LIBM_SCCS) && !defined(lint)
static char rcsid[] = "$NetBSD: $";
#endif
/*
* modfl(long double x, long double *iptr)
* return fraction part of x, and return x's integral part in *iptr.
* Method:
* Bit twiddling.
*
* Exception:
* No exception.
*/
#include <math.h>
#include <math_private.h>
#include <math_ldbl_opt.h>
static const long double one = 1.0;
long double __modfl(long double x, long double *iptr)
{
int64_t i0,i1,j0;
uint64_t i;
double xhi, xlo;
ldbl_unpack (x, &xhi, &xlo);
EXTRACT_WORDS64 (i0, xhi);
EXTRACT_WORDS64 (i1, xlo);
i1 &= 0x000fffffffffffffLL;
j0 = ((i0>>52)&0x7ff)-0x3ff; /* exponent of x */
if(j0<52) { /* integer part in high x */
if(j0<0) { /* |x|<1 */
/* *iptr = +-0 */
INSERT_WORDS64 (xhi, i0&0x8000000000000000ULL);
*iptr = xhi;
return x;
} else {
i = (0x000fffffffffffffLL)>>j0;
if(((i0&i)|(i1&0x7fffffffffffffffLL))==0) { /* x is integral */
*iptr = x;
/* return +-0 */
INSERT_WORDS64 (xhi, i0&0x8000000000000000ULL);
x = xhi;
return x;
} else {
INSERT_WORDS64 (xhi, i0&(~i));
*iptr = xhi;
return x - *iptr;
}
}
} else if (j0>103) { /* no fraction part */
*iptr = x*one;
/* We must handle NaNs separately. */
if ((i0 & 0x7fffffffffffffffLL) > 0x7ff0000000000000LL)
return x*one;
/* return +-0 */
INSERT_WORDS64 (xhi, i0&0x8000000000000000ULL);
x = xhi;
return x;
} else { /* fraction part in low x */
i = -1ULL>>(j0-52);
if((i1&i)==0) { /* x is integral */
*iptr = x;
/* return +-0 */
INSERT_WORDS64 (xhi, i0&0x8000000000000000ULL);
x = xhi;
return x;
} else {
INSERT_WORDS64 (xhi, i0);
INSERT_WORDS64 (xlo, i1&(~i));
*iptr = ldbl_pack (xhi, xlo);
return x - *iptr;
}
}
}
#if IS_IN (libm)
long_double_symbol (libm, __modfl, modfl);
#else
long_double_symbol (libc, __modfl, modfl);
#endif
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