1 /* Round to int long double floating-point values.
2 IBM extended format long double version.
3 Copyright (C) 2006 Free Software Foundation, Inc.
4 This file is part of the GNU C Library.
6 The GNU C Library is free software; you can redistribute it and/or
7 modify it under the terms of the GNU Lesser General Public
8 License as published by the Free Software Foundation; either
9 version 2.1 of the License, or (at your option) any later version.
11 The GNU C Library is distributed in the hope that it will be useful,
12 but WITHOUT ANY WARRANTY; without even the implied warranty of
13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
14 Lesser General Public License for more details.
16 You should have received a copy of the GNU Lesser General Public
17 License along with the GNU C Library; if not, write to the Free
18 Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
21 /* This has been coded in assembler because GCC makes such a mess of it
22 when it's coded in C. */
25 #include <fenv_libc.h>
26 #include <math_ldbl_opt.h>
33 __rintl (long double x)
40 double xh, xl, hi, lo;
42 ldbl_unpack (x, &xh, &xl);
44 /* Return Inf, Nan, +/-0 unchanged. */
45 if (__builtin_expect (xh != 0.0
46 && __builtin_isless (__builtin_fabs (xh),
47 __builtin_inf ()), 1))
50 int save_round = fegetround ();
52 /* Long double arithmetic, including the canonicalisation below,
53 only works in round-to-nearest mode. */
54 fesetround (FE_TONEAREST);
56 /* Convert the high double to integer. */
58 hi = ldbl_nearbyint (xh);
60 /* Subtract integral high part from the value. If the low double
61 happens to be exactly 0.5 or -0.5, you might think that this
62 subtraction could result in an incorrect conversion. For
63 instance, subtracting an odd number would cause this function
64 to round in the wrong direction. However, if we have a
65 canonical long double with the low double 0.5 or -0.5, then the
66 high double must be even. */
68 ldbl_canonicalize (&xh, &xl);
70 /* Now convert the low double, adjusted for any remainder from the
72 lo = ldbl_nearbyint (xh);
75 ldbl_canonicalize (&xh, &xl);
80 if (xl > 0.0 && xh == 0.5)
82 else if (xl < 0.0 && -xh == 0.5)
92 if (xh < 0.0 || (xh == 0.0 && xl < 0.0))
98 if (xh > 0.0 || (xh == 0.0 && xl > 0.0))
103 /* Ensure the final value is canonical. In certain cases,
104 rounding causes hi,lo calculated so far to be non-canonical. */
107 ldbl_canonicalize (&xh, &xl);
109 /* Ensure we return -0 rather than +0 when appropriate. */
111 xh = -__builtin_fabs (xh);
113 fesetround (save_round);
116 return ldbl_pack (xh, xl);
119 long_double_symbol (libm, __rintl, rintl);