glibc/sysdeps/ieee754/soft-fp/s_fsub.c

/* Subtract double values, narrowing the result to float, using soft-fp.
   Copyright (C) 2018-2023 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
   <https://www.gnu.org/licenses/>.  */

#define f32subf64 __hide_f32subf64
#define f32subf32x __hide_f32subf32x
#define fsubl __hide_fsubl
#include <math.h>
#undef f32subf64
#undef f32subf32x
#undef fsubl

#include <math-narrow.h>
#include <soft-fp.h>
#include <single.h>
#include <double.h>

float
__fsub (double x, double y)
{
  FP_DECL_EX;
  FP_DECL_D (X);
  FP_DECL_D (Y);
  FP_DECL_D (R);
  FP_DECL_S (RN);
  float ret;

  FP_INIT_ROUNDMODE;
  FP_UNPACK_SEMIRAW_D (X, x);
  FP_UNPACK_SEMIRAW_D (Y, y);
  FP_SUB_D (R, X, Y);
#if _FP_W_TYPE_SIZE < _FP_FRACBITS_D
  FP_TRUNC (S, D, 1, 2, RN, R);
#else
  FP_TRUNC (S, D, 1, 1, RN, R);
#endif
  FP_PACK_SEMIRAW_S (ret, RN);
  FP_HANDLE_EXCEPTIONS;
  CHECK_NARROW_SUB (ret, x, y);
  return ret;
}
libm_alias_float_double (sub)