scroll.c

来自「一个非常优秀的操作系统源代码」· C语言 代码 · 共 38 行

/* Gemini Nucleus
 *
 * $Id: scroll.c,v 1.1.1.1 2000/03/24 17:46:32 verdich Exp $
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version 2
 * of the License, or (at your option) any later version.
 *
 * This program 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 General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA. 
 */

#include <string.h>

int
scroll()
{
  static char *screen_buffer = (char *)(0xb8000);
  int i;

  for(i = 0; i < 24; i++)
    {
      memcpy(screen_buffer + i * 160, 
	     screen_buffer + (i + 1) * 160,
	     160);
    }
  for(i = 0; i < 80; i++)
    screen_buffer[24 * 160 + i * 2] = ' '; 
  return 0;
}