diff options
Diffstat (limited to 'sysdeps/libm-ieee754/s_round.c')
| -rw-r--r-- | sysdeps/libm-ieee754/s_round.c | 97 |
1 files changed, 97 insertions, 0 deletions
diff --git a/sysdeps/libm-ieee754/s_round.c b/sysdeps/libm-ieee754/s_round.c new file mode 100644 index 0000000000..fdb17f8de8 --- /dev/null +++ b/sysdeps/libm-ieee754/s_round.c @@ -0,0 +1,97 @@ +/* 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 Library General Public License as + published by the Free Software Foundation; either version 2 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 + Library General Public License for more details. + + You should have received a copy of the GNU Library General Public + License along with the GNU C Library; see the file COPYING.LIB. 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; +} +weak_alias (__round, round) +#ifdef NO_LONG_DOUBLE +strong_alias (__round, __roundl) +weak_alias (__round, roundl) +#endif |