glibc/sysdeps/riscv/rvf/s_roundevenf.c

/* Round to nearest integer value, rounding halfway cases to even.
   Copyright (C) 2017-2019 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, see
   <http://www.gnu.org/licenses/>.  */

#include <math.h>
#include <fenv_private.h>
#include <libm-alias-float.h>
#include <stdint.h>

float
__roundevenf (float x)
{
  int flags = riscv_getflags ();
  bool nan = isnan (x);
  float mag = fabsf (x);

  if (nan)
    return x + x;

  if (mag < (1 << __FLT_MANT_DIG__))
    {
      int32_t i;
      float new_x;

      asm volatile ("fcvt.w.s %0, %1, rne" : "=r" (i) : "f" (x));
      asm volatile ("fcvt.s.w %0, %1, rne" : "=f" (new_x) : "r" (i));

      /* roundeven(-0) == -0, and in general we'll always have the same
	 sign as our input.  */
      x = copysignf (new_x, x);

      riscv_setflags (flags);
    }

  return x;
}

libm_alias_float (__roundeven, roundeven)