stage1/vga.c

   1 #include "kernel.h"
   2
   3 u16 vrow, vcol, vtone;
   4 uc *vscr;
   5
   6 // v terminal drivers
   7 uc
   8 vcolour (fg, bg)
   9 {
  10     return (uc)fg | ((uc)bg << 4);
  11 }
  12
  13 u16
  14 vind (x, y)
  15 {
  16     return 2 * (y * WIDTH + x);
  17 }
  18
  19 u16
  20 vcind (x, y)
  21 {
  22     return 2 * (y * WIDTH + x) + 1;
  23 }
  24
  25 vputat (c, colour, x, y)
  26 {
  27     vscr[vind (x, y)] = c;
  28     vscr[vcind (x,y)] = colour;
  29 }
  30
  31 vini ()
  32 {
  33     int fg, bg, i, j;
  34
  35     vrow = vcol = 0;
  36
  37     fg = GRAY;
  38     bg = BLACK;
  39     vtone = vcolour (fg, bg);
  40
  41     vscr = (uc *)0x0B8000;
  42
  43     for (i = 0; i < HEIGHT; ++i)
  44         for (j = 0; j < WIDTH; ++j)
  45             vputat (' ', vtone, j, i);
  46 }
  47
  48 vputc (c)
  49 uc c;
  50 {
  51     if (c == '\n')
  52         vcol = WIDTH;
  53     else
  54         vputat (c, vtone, vcol++, vrow);
  55
  56     if (vcol == WIDTH) {
  57         vcol = 0;
  58         ++vrow;
  59     }
  60
  61     if (vrow == HEIGHT)
  62         vrow = 0;
  63 }
  64
  65 vput (s)
  66 uc *s;
  67 {
  68     while (*s)
  69         vputc (*s++);
  70 }