fmod.c

上一个上传的有问题,这个是好的。visopsys包括系统内核和GUI的全部SOURCE code ,还包括一些基本的docs文档。里面src子目录对应所有SOURCE code.对于想研究操作系统的朋

// 
//  Visopsys
//  Copyright (C) 1998-2007 J. Andrew McLaughlin
//  
//  This 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.
//
//  This 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 this library; if not, write to the Free Software Foundation,
//  Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
//
//  fmod.c
//

// This is the standard "fmod" function, as found in standard C libraries

#include <math.h>
#include <errno.h>


double fmod(double x, double y)
{
  // The fmod() function computes the remainder of dividing x by y.
  // The return value is x - n * y, where n is the quotient of x / y,
  // rounded towards zero to an integer.

  // In other words, the fmod() function returns the value x - n * y,
  // for some integer n such that, if y is non-zero, the result has the
  // same sign as x and magnitude less than the magnitude of y.

  double m = 0;

  if (y == 0)
    {
      m = 0;
      errno = ERR_DIVIDEBYZERO;
    }
  else
    m = (x - (floor(x / y) * y));

  return (x);
}