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Diffstat (limited to 'sysdeps/ieee754/ldbl-128ibm/s_rintl.c')
-rw-r--r--sysdeps/ieee754/ldbl-128ibm/s_rintl.c119
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
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index 0000000000..1f4e33f91c
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+++ b/sysdeps/ieee754/ldbl-128ibm/s_rintl.c
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+/* 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);