getc.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.
//
//  getc.c
//

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

#include <stdio.h>
#include <errno.h>
#include <sys/api.h>


int getc(FILE *theStream)
{
  // getc() is equivalent to fgetc() except that it may be implemented as
  // a macro which evaluates stream more than once.  OK, it's not a macro,
  // and it's only going to be partially implemented right now.

  int status = 0;
  char c = '\0';

  if (visopsys_in_kernel)
    {
      errno = ERR_BUG;
      return (EOF);
    }

  if (theStream != stdin)
    {
      // We are only implementing for stdin at the moment
      errno = ERR_NOTIMPLEMENTED;
      return (EOF);
    }

  // Get a character from the text input stream
  status = textInputGetc(&c);
  if (status < 0)
    {
      errno = status;
      return (EOF);
    }

  return ((int) c);
}