term/i386/pc/vga_text.c

   1 /*
   2  *  GRUB  --  GRand Unified Bootloader
   3  *  Copyright (C) 2007  Free Software Foundation, Inc.
   4  *
   5  *  GRUB is free software: you can redistribute it and/or modify
   6  *  it under the terms of the GNU General Public License as published by
   7  *  the Free Software Foundation, either version 3 of the License, or
   8  *  (at your option) any later version.
   9  *
  10  *  GRUB is distributed in the hope that it will be useful,
  11  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13  *  GNU General Public License for more details.
  14  *
  15  *  You should have received a copy of the GNU General Public License
  16  *  along with GRUB.  If not, see <http://www.gnu.org/licenses/>.
  17  */
  18
  19 #include <grub/machine/console.h>
  20 #include <grub/cpu/io.h>
  21 #include <grub/types.h>
  22
  23 #define COLS    80
  24 #define ROWS    25
  25
  26 static int grub_curr_x, grub_curr_y;
  27
  28 #define VGA_TEXT_SCREEN         0xb8000
  29
  30 #define CRTC_ADDR_PORT          0x3D4
  31 #define CRTC_DATA_PORT          0x3D5
  32
  33 #define CRTC_CURSOR             0x0a
  34 #define CRTC_CURSOR_ADDR_HIGH   0x0e
  35 #define CRTC_CURSOR_ADDR_LOW    0x0f
  36
  37 #define CRTC_CURSOR_DISABLE     (1 << 5)
  38
  39 static void
  40 screen_write_char (int x, int y, short c)
  41 {
  42   ((short *) VGA_TEXT_SCREEN)[y * COLS + x] = c;
  43 }
  44
  45 static short
  46 screen_read_char (int x, int y)
  47 {
  48   return ((short *) VGA_TEXT_SCREEN)[y * COLS + x];
  49 }
  50
  51 static void
  52 update_cursor (void)
  53 {
  54   unsigned int pos = grub_curr_y * COLS + grub_curr_x;
  55   grub_outb (CRTC_CURSOR_ADDR_HIGH, CRTC_ADDR_PORT);
  56   grub_outb (pos >> 8, CRTC_DATA_PORT);
  57   grub_outb (CRTC_CURSOR_ADDR_LOW, CRTC_ADDR_PORT);
  58   grub_outb (pos & 0xFF, CRTC_DATA_PORT);
  59 }
  60
  61 static void
  62 inc_y (void)
  63 {
  64   grub_curr_x = 0;
  65   if (grub_curr_y < ROWS - 1)
  66     grub_curr_y++;
  67   else
  68     {
  69       int x, y;
  70       for (y = 0; y < ROWS; y++)
  71         for (x = 0; x < COLS; x++)
  72           screen_write_char (x, y, screen_read_char (x, y + 1));
  73     }
  74 }
  75
  76 static void
  77 inc_x (void)
  78 {
  79   if (grub_curr_x >= COLS - 2)
  80     inc_y ();
  81   else
  82     grub_curr_x++;
  83 }
  84
  85 void
  86 grub_console_real_putchar (int c)
  87 {
  88   switch (c)
  89     {
  90       case '\b':
  91         if (grub_curr_x != 0)
  92           screen_write_char (grub_curr_x--, grub_curr_y, ' ');
  93         break;
  94       case '\n':
  95         inc_y ();
  96         break;
  97       case '\r':
  98         grub_curr_x = 0;
  99         break;
 100       default:
 101         screen_write_char (grub_curr_x,
 102                            grub_curr_y, c | (grub_console_cur_color << 8));
 103         inc_x ();
 104     }
 105
 106   update_cursor ();
 107 }
 108
 109 grub_uint16_t
 110 grub_console_getxy (void)
 111 {
 112   return (grub_curr_x << 8) | grub_curr_y;
 113 }
 114
 115 void
 116 grub_console_gotoxy (grub_uint8_t x, grub_uint8_t y)
 117 {
 118   grub_curr_x = x;
 119   grub_curr_y = y;
 120   update_cursor ();
 121 }
 122
 123 void
 124 grub_console_cls (void)
 125 {
 126   int i;
 127   for (i = 0; i < ROWS * COLS; i++)
 128     ((short *) VGA_TEXT_SCREEN)[i] = ' ' | (grub_console_cur_color << 8);
 129   grub_console_gotoxy (0, 0);
 130 }
 131
 132 void
 133 grub_console_setcursor (int on)
 134 {
 135   grub_uint8_t old;
 136   grub_outb (CRTC_CURSOR, CRTC_ADDR_PORT);
 137   old = grub_inb (CRTC_DATA_PORT);
 138   if (on)
 139     grub_outb (old & ~CRTC_CURSOR_DISABLE, CRTC_DATA_PORT);
 140   else
 141     grub_outb (old | CRTC_CURSOR_DISABLE, CRTC_DATA_PORT);
 142 }