diff options
Diffstat (limited to 'sysdeps/ieee754/ldbl-128ibm/s_rintl.c')
| -rw-r--r-- | sysdeps/ieee754/ldbl-128ibm/s_rintl.c | 119 |
1 files changed, 119 insertions, 0 deletions
diff --git a/sysdeps/ieee754/ldbl-128ibm/s_rintl.c b/sysdeps/ieee754/ldbl-128ibm/s_rintl.c new file mode 100644 index 0000000..1f4e33f --- /dev/null +++ b/sysdeps/ieee754/ldbl-128ibm/s_rintl.c @@ -0,0 +1,119 @@ +/* Round to int long double floating-point values. + IBM extended format long double version. + Copyright (C) 2006 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, write to the Free + Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA + 02111-1307 USA. */ + +/* This has been coded in assembler because GCC makes such a mess of it + when it's coded in C. */ + +#include <math.h> +#include <fenv_libc.h> +#include <math_ldbl_opt.h> +#include <float.h> +#include <ieee754.h> + + +#ifdef __STDC__ +long double +__rintl (long double x) +#else +long double +__rintl (x) + long double x; +#endif +{ + double xh, xl, hi, lo; + + ldbl_unpack (x, &xh, &xl); + + /* Return Inf, Nan, +/-0 unchanged. */ + if (__builtin_expect (xh != 0.0 + && __builtin_isless (__builtin_fabs (xh), + __builtin_inf ()), 1)) + { + double orig_xh; + int save_round = fegetround (); + + /* Long double arithmetic, including the canonicalisation below, + only works in round-to-nearest mode. */ + fesetround (FE_TONEAREST); + + /* Convert the high double to integer. */ + orig_xh = xh; + hi = ldbl_nearbyint (xh); + + /* Subtract integral high part from the value. If the low double + happens to be exactly 0.5 or -0.5, you might think that this + subtraction could result in an incorrect conversion. For + instance, subtracting an odd number would cause this function + to round in the wrong direction. However, if we have a + canonical long double with the low double 0.5 or -0.5, then the + high double must be even. */ + xh -= hi; + ldbl_canonicalize (&xh, &xl); + + /* Now convert the low double, adjusted for any remainder from the + high double. */ + lo = ldbl_nearbyint (xh); + + xh -= lo; + ldbl_canonicalize (&xh, &xl); + + switch (save_round) + { + case FE_TONEAREST: + if (xl > 0.0 && xh == 0.5) + lo += 1.0; + else if (xl < 0.0 && -xh == 0.5) + lo -= 1.0; + break; + + case FE_TOWARDZERO: + if (orig_xh < 0.0) + goto do_up; + /* Fall thru */ + + case FE_DOWNWARD: + if (xh < 0.0 || (xh == 0.0 && xl < 0.0)) + lo -= 1.0; + break; + + case FE_UPWARD: + do_up: + if (xh > 0.0 || (xh == 0.0 && xl > 0.0)) + lo += 1.0; + break; + } + + /* Ensure the final value is canonical. In certain cases, + rounding causes hi,lo calculated so far to be non-canonical. */ + xh = hi; + xl = lo; + ldbl_canonicalize (&xh, &xl); + + /* Ensure we return -0 rather than +0 when appropriate. */ + if (orig_xh < 0.0) + xh = -__builtin_fabs (xh); + + fesetround (save_round); + } + + return ldbl_pack (xh, xl); +} + +long_double_symbol (libm, __rintl, rintl); |