putchar.c

一个非常优秀的操作系统源代码

/* Gemini Nucleus
 *
 * $Id: putchar.c,v 1.2 2000/04/04 09:03:38 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 <debug/cursor.h>
#include <debug/scroll.h>

int
aputchar(int a, int c)
{
  static int x = -1;
  static int y = -1;
  static char *screen_buffer = (char *)(0xb8000);

  cursor_get(&x, &y);
  switch (c) 
    {
    case '\n':
      x = 0;
      y++;
      break;
    case '\t':
      x += 8 - (x % 8);
      break;
    default:
      screen_buffer[(x + y * 80) * 2] = c;
      screen_buffer[(x + y * 80) * 2 + 1] = a;
      x++;
      break;
    }
  if (x >= 80) 
    {
      x -= 80;
      y++;
    }
  if (y >= 25)
    {
      scroll();
      y--;
    }
  cursor_set(x, y);
  return 0;
}