term/i386/pc/vga_text.c

   1 /*
   2  *  GRUB  --  GRand Unified Bootloader
   3  *  Copyright (C) 2007, 2008  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/dl.h>
  20 #include <grub/i386/vga_common.h>
  21 #include <grub/i386/io.h>
  22 #include <grub/types.h>
  23
  24 #define COLS    80
  25 #define ROWS    25
  26
  27 static int grub_curr_x, grub_curr_y;
  28
  29 #define VGA_TEXT_SCREEN         0xb8000
  30
  31 #define CRTC_ADDR_PORT          0x3D4
  32 #define CRTC_DATA_PORT          0x3D5
  33
  34 #define CRTC_CURSOR             0x0a
  35 #define CRTC_CURSOR_ADDR_HIGH   0x0e
  36 #define CRTC_CURSOR_ADDR_LOW    0x0f
  37
  38 #define CRTC_CURSOR_DISABLE     (1 << 5)
  39
  40 static void
  41 screen_write_char (int x, int y, short c)
  42 {
  43   ((short *) VGA_TEXT_SCREEN)[y * COLS + x] = c;
  44 }
  45
  46 static short
  47 screen_read_char (int x, int y)
  48 {
  49   return ((short *) VGA_TEXT_SCREEN)[y * COLS + x];
  50 }
  51
  52 static void
  53 update_cursor (void)
  54 {
  55   unsigned int pos = grub_curr_y * COLS + grub_curr_x;
  56   grub_outb (CRTC_CURSOR_ADDR_HIGH, CRTC_ADDR_PORT);
  57   grub_outb (pos >> 8, CRTC_DATA_PORT);
  58   grub_outb (CRTC_CURSOR_ADDR_LOW, CRTC_ADDR_PORT);
  59   grub_outb (pos & 0xFF, CRTC_DATA_PORT);
  60 }
  61
  62 static void
  63 inc_y (void)
  64 {
  65   grub_curr_x = 0;
  66   if (grub_curr_y < ROWS - 1)
  67     grub_curr_y++;
  68   else
  69     {
  70       int x, y;
  71       for (y = 0; y < ROWS; y++)
  72         for (x = 0; x < COLS; x++)
  73           screen_write_char (x, y, screen_read_char (x, y + 1));
  74     }
  75 }
  76
  77 static void
  78 inc_x (void)
  79 {
  80   if (grub_curr_x >= COLS - 2)
  81     inc_y ();
  82   else
  83     grub_curr_x++;
  84 }
  85
  86 void
  87 grub_console_real_putchar (int c)
  88 {
  89   switch (c)
  90     {
  91       case '\b':
  92         if (grub_curr_x != 0)
  93           screen_write_char (grub_curr_x--, grub_curr_y, ' ');
  94         break;
  95       case '\n':
  96         inc_y ();
  97         break;
  98       case '\r':
  99         grub_curr_x = 0;
 100         break;
 101       default:
 102         screen_write_char (grub_curr_x,
 103                            grub_curr_y, c | (grub_console_cur_color << 8));
 104         inc_x ();
 105     }
 106
 107   update_cursor ();
 108 }
 109
 110 static grub_uint16_t
 111 grub_vga_text_getxy (void)
 112 {
 113   return (grub_curr_x << 8) | grub_curr_y;
 114 }
 115
 116 static void
 117 grub_vga_text_gotoxy (grub_uint8_t x, grub_uint8_t y)
 118 {
 119   grub_curr_x = x;
 120   grub_curr_y = y;
 121   update_cursor ();
 122 }
 123
 124 static void
 125 grub_vga_text_cls (void)
 126 {
 127   int i;
 128   for (i = 0; i < ROWS * COLS; i++)
 129     ((short *) VGA_TEXT_SCREEN)[i] = ' ' | (grub_console_cur_color << 8);
 130   grub_vga_text_gotoxy (0, 0);
 131 }
 132
 133 static void
 134 grub_vga_text_setcursor (int on)
 135 {
 136   grub_uint8_t old;
 137   grub_outb (CRTC_CURSOR, CRTC_ADDR_PORT);
 138   old = grub_inb (CRTC_DATA_PORT);
 139   if (on)
 140     grub_outb (old & ~CRTC_CURSOR_DISABLE, CRTC_DATA_PORT);
 141   else
 142     grub_outb (old | CRTC_CURSOR_DISABLE, CRTC_DATA_PORT);
 143 }
 144
 145 static grub_err_t
 146 grub_vga_text_init_fini ()
 147 {
 148   grub_vga_text_cls ();
 149   return 0;
 150 }
 151
 152 static struct grub_term_output grub_vga_text_term =
 153   {
 154     .name = "vga_text",
 155     .init = grub_vga_text_init_fini,
 156     .fini = grub_vga_text_init_fini,
 157     .putchar = grub_console_putchar,
 158     .getcharwidth = grub_console_getcharwidth,
 159     .getwh = grub_console_getwh,
 160     .getxy = grub_vga_text_getxy,
 161     .gotoxy = grub_vga_text_gotoxy,
 162     .cls = grub_vga_text_cls,
 163     .setcolorstate = grub_console_setcolorstate,
 164     .setcolor = grub_console_setcolor,
 165     .getcolor = grub_console_getcolor,
 166     .setcursor = grub_vga_text_setcursor,
 167   };
 168
 169 GRUB_MOD_INIT(vga_text)
 170 {
 171   grub_term_register_output (&grub_vga_text_term);
 172 }
 173
 174 GRUB_MOD_FINI(vga_text)
 175 {
 176   grub_term_unregister_output (&grub_vga_text_term);
 177 }