floor.c

来自「一个类似windows」· C语言 代码 · 共 41 行

/* Math functions for i387.
   Copyright (C) 1995, 1996, 1997 Free Software Foundation, Inc.
   This file is part of the GNU C Library.
   Contributed by John C. Bowman <[e-mail]>, 1995.

   The GNU C Library is free software; you can redistribute it and/or
   modify it under the terms of the GNU Library General Public License as
   published by the Free Software Foundation; either version 2 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
   Library General Public License for more details.

   You should have received a copy of the GNU Library General Public
   License along with the GNU C Library; see the file COPYING.LIB.  If not,
   write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
   Boston, MA 02111-1307, USA.  */

#include <math.h>

double floor (double __x);

double floor (double __x)
{
  register double __value;
#ifdef __GNUC__
  __volatile unsigned short int __cw, __cwtmp;

  __asm __volatile ("fnstcw %0" : "=m" (__cw));
  __cwtmp = (__cw & 0xf3ff) | 0x0400; /* rounding down */
  __asm __volatile ("fldcw %0" : : "m" (__cwtmp));
  __asm __volatile ("frndint" : "=t" (__value) : "0" (__x));
  __asm __volatile ("fldcw %0" : : "m" (__cw));
#else
  __value = linkme_floor(__x);
#endif /*__GNUC__*/
  return __value;
}