_num2str.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.
//
//  _num2str.c
//

// This is a generic function to turns a number into a string.

#include <errno.h>
#include <sys/cdefs.h>


void _num2str(unsigned num, char *string, int base, int sign)
{
  int digits = _digits(num, base, sign);
  int charCount = 0;
  unsigned place = 1;
  unsigned rem = 0;
  int count;

  if (string == NULL)
    {
      errno = ERR_NULLPARAMETER;
      return;
    }

  // Negative?
  if (sign && ((int) num < 0))
    {
      string[charCount++] = '-';
      num = ((int) num * -1);
      digits -= 1;
    }

  for (count = 0; count < (digits - 1); count ++)
    place *= (unsigned) base;

  while (place)
    {
      rem = (num % place);
      num = (num / place);

      if (num < 10)
	string[charCount++] = ('0' + num);
      else
	string[charCount++] = ('a' + (num - 10));
      num = rem;
      place /= (unsigned) base;
    }

  string[charCount] = '\0';

  // Done
  return;
}