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bba1419589
The ldbl-128ibm implementations of ceill, floorl, roundl, truncl, rintl and nearbyintl wrongly return an sNaN when given an sNaN argument. This patch fixes them to add such an argument to itself to turn it into a quiet NaN. (The code structure means this "else" case applies to any argument which is zero or not finite; it's OK to do this in all such cases.) Tested for powerpc. [BZ #20156] * sysdeps/ieee754/ldbl-128ibm/s_ceill.c (__ceill): Add high part to itself when zero or not finite. * sysdeps/ieee754/ldbl-128ibm/s_floorl.c (__floorl): Likewise. * sysdeps/ieee754/ldbl-128ibm/s_rintl.c (__rintl): Likewise. * sysdeps/ieee754/ldbl-128ibm/s_roundl.c (__roundl): Likewise. * sysdeps/ieee754/ldbl-128ibm/s_truncl.c (__truncl): Likewise.
130 lines
3.4 KiB
C
130 lines
3.4 KiB
C
/* Round to int long double floating-point values.
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IBM extended format long double version.
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Copyright (C) 2006-2016 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 2.1 of the License, or (at your option) any later version.
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The GNU C Library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with the GNU C Library; if not, see
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<http://www.gnu.org/licenses/>. */
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/* This has been coded in assembler because GCC makes such a mess of it
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when it's coded in C. */
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#include <math.h>
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#include <fenv.h>
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#include <math_ldbl_opt.h>
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#include <float.h>
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#include <ieee754.h>
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#ifdef USE_AS_NEARBYINTL
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# define rintl nearbyintl
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# define __rintl __nearbyintl
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#endif
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long double
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__rintl (long double x)
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{
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double xh, xl, hi, lo;
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ldbl_unpack (x, &xh, &xl);
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/* Return Inf, Nan, +/-0 unchanged. */
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if (__builtin_expect (xh != 0.0
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&& __builtin_isless (__builtin_fabs (xh),
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__builtin_inf ()), 1))
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{
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double orig_xh;
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int save_round = fegetround ();
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/* Long double arithmetic, including the canonicalisation below,
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only works in round-to-nearest mode. */
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#ifdef USE_AS_NEARBYINTL
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SET_RESTORE_ROUND_NOEX (FE_TONEAREST);
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#else
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fesetround (FE_TONEAREST);
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#endif
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/* Convert the high double to integer. */
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orig_xh = xh;
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hi = ldbl_nearbyint (xh);
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/* Subtract integral high part from the value. If the low double
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happens to be exactly 0.5 or -0.5, you might think that this
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subtraction could result in an incorrect conversion. For
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instance, subtracting an odd number would cause this function
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to round in the wrong direction. However, if we have a
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canonical long double with the low double 0.5 or -0.5, then the
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high double must be even. */
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xh -= hi;
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ldbl_canonicalize (&xh, &xl);
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/* Now convert the low double, adjusted for any remainder from the
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high double. */
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lo = ldbl_nearbyint (xh);
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xh -= lo;
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ldbl_canonicalize (&xh, &xl);
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switch (save_round)
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{
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case FE_TONEAREST:
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if (xl > 0.0 && xh == 0.5)
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lo += 1.0;
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else if (xl < 0.0 && -xh == 0.5)
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lo -= 1.0;
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break;
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case FE_TOWARDZERO:
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if (orig_xh < 0.0)
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goto do_up;
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/* Fall thru */
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case FE_DOWNWARD:
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if (xh < 0.0 || (xh == 0.0 && xl < 0.0))
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lo -= 1.0;
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break;
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case FE_UPWARD:
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do_up:
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if (xh > 0.0 || (xh == 0.0 && xl > 0.0))
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lo += 1.0;
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break;
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}
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/* Ensure the final value is canonical. In certain cases,
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rounding causes hi,lo calculated so far to be non-canonical. */
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xh = hi;
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xl = lo;
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ldbl_canonicalize (&xh, &xl);
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/* Ensure we return -0 rather than +0 when appropriate. */
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if (orig_xh < 0.0)
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xh = -__builtin_fabs (xh);
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#ifdef USE_AS_NEARBYINTL
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math_force_eval (xh);
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math_force_eval (xl);
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#else
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fesetround (save_round);
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#endif
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}
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else
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/* Quiet signaling NaN arguments. */
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xh += xh;
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return ldbl_pack (xh, xl);
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}
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long_double_symbol (libm, __rintl, rintl);
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