glibc/sysdeps/ieee754/dbl-64/s_nextup.c
Rajalakshmi Srinivasaraghavan 41a359e22f Add nextup and nextdown math functions
TS 18661 adds nextup and nextdown functions alongside nextafter to provide
support for float128 equivalent to it.  This patch adds nextupl, nextup,
nextupf, nextdownl, nextdown and nextdownf to libm before float128 support.

The nextup functions return the next representable value in the direction of
positive infinity and the nextdown functions return the next representable
value in the direction of negative infinity.  These are currently enabled
as GNU extensions.
2016-06-16 21:37:45 +05:30

59 lines
1.6 KiB
C

/* Return the least floating-point number greater than X.
Copyright (C) 2016 Free Software Foundation, Inc.
This file is part of the GNU C Library.
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
The GNU C Library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with the GNU C Library; if not, see
<http://www.gnu.org/licenses/>. */
#include <math.h>
#include <math_private.h>
/* Return the least floating-point number greater than X. */
double
__nextup (double x)
{
int32_t hx, ix;
u_int32_t lx;
EXTRACT_WORDS (hx, lx, x);
ix = hx & 0x7fffffff;
if (((ix >= 0x7ff00000) && ((ix - 0x7ff00000) | lx) != 0)) /* x is nan. */
return x + x;
if ((ix | lx) == 0)
return DBL_TRUE_MIN;
if (hx >= 0)
{ /* x > 0. */
if (isinf (x))
return x;
lx += 1;
if (lx == 0)
hx += 1;
}
else
{ /* x < 0. */
if (lx == 0)
hx -= 1;
lx -= 1;
}
INSERT_WORDS (x, hx, lx);
return x;
}
weak_alias (__nextup, nextup)
#ifdef NO_LONG_DOUBLE
strong_alias (__nextup, __nextupl)
weak_alias (__nextup, nextupl)
#endif