sysdeps/i386/fpu/s_fmax.S

   1 /* Compute maximum of two numbers, regarding NaN as missing argument.
   2    Copyright (C) 1997-2021 Free Software Foundation, Inc.
   3    This file is part of the GNU C Library.
   4    Contributed by Ulrich Drepper <drepper@cygnus.com>, 1997.
   5
   6    The GNU C Library is free software; you can redistribute it and/or
   7    modify it under the terms of the GNU Lesser General Public
   8    License as published by the Free Software Foundation; either
   9    version 2.1 of the License, or (at your option) any later version.
  10
  11    The GNU C Library is distributed in the hope that it will be useful,
  12    but WITHOUT ANY WARRANTY; without even the implied warranty of
  13    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14    Lesser General Public License for more details.
  15
  16    You should have received a copy of the GNU Lesser General Public
  17    License along with the GNU C Library; if not, see
  18    <https://www.gnu.org/licenses/>.  */
  19
  20 #include <sysdep.h>
  21 #include <libm-alias-double.h>
  22
  23         .text
  24 ENTRY(__fmax)
  25         fldl    12(%esp)        // y
  26         fxam
  27         fnstsw
  28         fldl    4(%esp)         // y : x
  29
  30         andb    $0x45, %ah
  31         cmpb    $0x01, %ah
  32         je      1f              // y == NaN
  33
  34         fucom   %st(1)
  35         fnstsw
  36         sahf
  37         jnc     1f
  38
  39         fxch    %st(1)
  40 1:      fstp    %st(1)
  41
  42         ret
  43 END(__fmax)
  44 libm_alias_double (__fmax, fmax)