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
   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 #include <sysdep.h>
  20 #include <libm-alias-double.h>
  21
  22         .text
  23 ENTRY(__fmax)
  24         fldl    12(%esp)        // y
  25         fxam
  26         fnstsw
  27         fldl    4(%esp)         // y : x
  28
  29         andb    $0x45, %ah
  30         cmpb    $0x01, %ah
  31         je      1f              // y == NaN
  32
  33         fucom   %st(1)
  34         fnstsw
  35         sahf
  36         jnc     1f
  37
  38         fxch    %st(1)
  39 1:      fstp    %st(1)
  40
  41         ret
  42 END(__fmax)
  43 libm_alias_double (__fmax, fmax)