e_sqrt.c

来自「linux下的C语言库源码有一百多M解压后很不错」· C语言 代码 · 共 30 行

/* Double-precision floating point square root.
   Copyright (C) 1997, 2002, 2003, 2004, 2006 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, write to the Free
   Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
   02111-1307 USA.  */

#include <math.h>
#include <math_private.h>

double
__ieee754_sqrt (double x)
{
  double z;
  __asm __volatile ("fsqrt %0,%1" : "=f" (z) : "f" (x));
  return z;
}