sysdeps/riscv/rv64/rvd/s_rint.c

   1 /* rint().  RISC-V version.
   2    Copyright (C) 2017-2022 Free Software Foundation, Inc.
   3    This file is part of the GNU C Library.
   4
   5    The GNU C Library is free software; you can redistribute it and/or
   6    modify it under the terms of the GNU Lesser General Public
   7    License as published by the Free Software Foundation; either
   8    version 2.1 of the License, or (at your option) any later version.
   9
  10    The GNU C Library is distributed in the hope that it will be useful,
  11    but WITHOUT ANY WARRANTY; without even the implied warranty of
  12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13    Lesser General Public License for more details.
  14
  15    You should have received a copy of the GNU Lesser General Public
  16    License along with the GNU C Library.  If not, see
  17    <https://www.gnu.org/licenses/>.  */
  18
  19 #define NO_MATH_REDIRECT
  20 #include <math.h>
  21 #include <stdbool.h>
  22 #include <libm-alias-double.h>
  23 #include <stdint.h>
  24
  25 double
  26 __rint (double x)
  27 {
  28   bool nan;
  29   double mag;
  30
  31   nan = isnan (x);
  32   mag = fabs (x);
  33
  34   if (nan)
  35     return x + x;
  36
  37   if (mag < (1ULL << __DBL_MANT_DIG__))
  38     {
  39       int64_t i;
  40       double new_x;
  41
  42       asm ("fcvt.l.d %0, %1" : "=r" (i) : "f" (x));
  43       asm ("fcvt.d.l %0, %1" : "=f" (new_x) : "r" (i));
  44
  45       /* rint(-0) == -0, and in general we'll always have the same
  46          sign as our input.  */
  47       x = copysign (new_x, x);
  48     }
  49
  50   return x;
  51 }
  52
  53 libm_alias_double (__rint, rint)