src/console/vga_console.c

   1 /*
   2  *
   3  * modified from original freebios code
   4  * by Steve M. Gehlbach <steve@kesa.com>
   5  *
   6  */
   7
   8 /*
   9  * TODO:
  10  * * make vga_console_init take FB location, columns, lines and starting
  11  *   column/line.
  12  * * track a word offset, and not columns/lines. The offset is needed more
  13  *   often than columns/lines and the latter two can be calculated easily.
  14  * * then implement real vga scrolling, instead of memcpying stuff around.
  15  *
  16  * -- libv.
  17  */
  18
  19 #include <arch/io.h>
  20 #include <string.h>
  21 #include <pc80/vga_io.h>
  22 #include <pc80/vga.h>
  23 #include <console/console.h>
  24
  25 /* The video buffer, should be replaced by symbol in ldscript.ld */
  26 static char *vidmem;
  27 static int total_lines, total_columns;
  28 static int current_line, current_column;
  29 static int vga_console_inited = 0;
  30
  31 /*
  32  *
  33  */
  34 void vga_console_init(void)
  35 {
  36         vidmem = (char *) VGA_FB;
  37         total_columns = VGA_COLUMNS;
  38         total_lines = VGA_LINES;
  39         current_column = 0;
  40         current_line = 0;
  41
  42         vga_console_inited = 1;
  43 }
  44
  45 static void vga_scroll(void)
  46 {
  47         int i;
  48
  49         memcpy(vidmem, vidmem + total_columns * 2, (total_lines - 1) * total_columns * 2);
  50         for (i = (total_lines - 1) * total_columns * 2; i < total_lines * total_columns * 2; i += 2)
  51                 vidmem[i] = ' ';
  52 }
  53
  54 static void
  55 vga_tx_byte(unsigned char byte)
  56 {
  57         if (!vga_console_inited)
  58             return;
  59
  60         switch (byte) {
  61         case '\n':
  62                 current_line++;
  63                 current_column = 0;
  64                 break;
  65         case '\r':
  66                 current_column = 0;
  67                 break;
  68         case '\b':
  69                 current_column--;
  70                 break;
  71         case '\t':
  72                 current_column += 4;
  73                 break;
  74         case '\a': /* beep */
  75                 break;
  76         default:
  77                 vidmem[((current_column + (current_line * total_columns)) * 2)] = byte;
  78                 vidmem[((current_column + (current_line * total_columns)) * 2) +1] = 0x07;
  79                 current_column++;
  80                 break;
  81         }
  82
  83         if (current_column < 0)
  84                 current_column = 0;
  85         if (current_column >= total_columns) {
  86                 current_line++;
  87                 current_column = 0;
  88         }
  89         if (current_line >= total_lines) {
  90                 vga_scroll();
  91                 current_line--;
  92         }
  93
  94         /* move the cursor */
  95         vga_cr_write(0x0E, (current_column + (current_line * total_columns)) >> 8);
  96         vga_cr_write(0x0F, (current_column + (current_line * total_columns)) & 0x0ff);
  97 }
  98
  99 static const struct console_driver vga_console __console ={
 100         .init    = 0,
 101         .tx_byte = vga_tx_byte,
 102         .rx_byte = 0,
 103         .tst_byte = 0,
 104 };