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- /* Round double to integer away from zero.
- Copyright (C) 1997 Free Software Foundation, Inc.
- This file is part of the GNU C Library.
- Contributed by Ulrich Drepper <drepper@cygnus.com>, 1997.
- 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, write to the Free
- Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
- 02111-1307 USA. */
- #include <math.h>
- #include "math_private.h"
- static const double huge = 1.0e300;
- double
- round (double x)
- {
- int32_t i0, j0;
- u_int32_t i1;
- EXTRACT_WORDS (i0, i1, x);
- j0 = ((i0 >> 20) & 0x7ff) - 0x3ff;
- if (j0 < 20)
- {
- if (j0 < 0)
- {
- if (huge + x > 0.0)
- {
- i0 &= 0x80000000;
- if (j0 == -1)
- i0 |= 0x3ff00000;
- i1 = 0;
- }
- }
- else
- {
- u_int32_t i = 0x000fffff >> j0;
- if (((i0 & i) | i1) == 0)
- /* X is integral. */
- return x;
- if (huge + x > 0.0)
- {
- /* Raise inexact if x != 0. */
- i0 += 0x00080000 >> j0;
- i0 &= ~i;
- i1 = 0;
- }
- }
- }
- else if (j0 > 51)
- {
- if (j0 == 0x400)
- /* Inf or NaN. */
- return x + x;
- else
- return x;
- }
- else
- {
- u_int32_t i = 0xffffffff >> (j0 - 20);
- if ((i1 & i) == 0)
- /* X is integral. */
- return x;
- if (huge + x > 0.0)
- {
- /* Raise inexact if x != 0. */
- u_int32_t j = i1 + (1 << (51 - j0));
- if (j < i1)
- i0 += 1;
- i1 = j;
- }
- i1 &= ~i;
- }
- INSERT_WORDS (x, i0, i1);
- return x;
- }
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