mbtowc.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.
//
//  mbtowc.c
//

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

#include <stdlib.h>


int mbtowc(wchar_t *wc, const char *bytes, size_t n)
{
  // Here's how the Linux man page describes this function:
  //
  // The main case for this function is when bytes is not NULL and pwc is not
  // NULL.  In this case, the mbtowc function inspects at most n bytes of the
  // multibyte string starting at bytes, extracts the next complete multibyte
  // character, converts it to a wide character and stores it at *pwc.  It
  // updates an internal shift state only known to the mbtowc function. If
  // bytes does not point to a '\0' byte, it returns the number of bytes
  // that were consumed from bytes, otherwise it returns 0.
  //
  // If the n bytes starting at bytes do not contain a complete multibyte
  // character, or if they contain an invalid multibyte sequence, mbtowc
  // returns -1.  This can happen even if n >= MB_CUR_MAX, if the multibyte
  // string contains redundant shift sequences.
  //
  // A different case is when bytes is not NULL but pwc is NULL.  In this
  // case the mbtowc function behaves as above, excepts that it does not store
  // the converted wide character in memory.
  //
  // A third case is when bytes is NULL.  In this case, pwc and n are ignored.
  // The mbtowc function resets the shift state, only known to this func挕