console.c

#include "types.h"
#include "x86.h"
#include "traps.h"
#include "defs.h"
#include "spinlock.h"
#include "dev.h"
#include "param.h"

struct spinlock console_lock;
int panicked = 0;
int use_console_lock = 0;

// Copy console output to parallel port, which you can tell
// .bochsrc to copy to the stdout:
//   parport1: enabled=1, file="/dev/stdout"
static void
lpt_putc(int c)
{
  int i;

  for(i = 0; !(inb(0x378+1) & 0x80) && i < 12800; i++)
    ;
  outb(0x378+0, c);
  outb(0x378+2, 0x08|0x04|0x01);
  outb(0x378+2, 0x08);
}

static void
cons_putc(int c)
{
  int crtport = 0x3d4; // io port of CGA
  ushort *crt = (ushort*) 0xB8000; // base of CGA memory
  int ind;

  if(panicked){
    cli();
    for(;;)
      ;
  }

  lpt_putc(c);

  // cursor position, 16 bits, col + 80*row
  outb(crtport, 14);
  ind = inb(crtport + 1) << 8;
  outb(crtport, 15);
  ind |= inb(crtport + 1);

  c &= 0xff;

  if(c == '\n'){
    ind -= (ind % 80);
    ind += 80;
  } else {
    c |= 0x0700; // black on white
    crt[ind] = c;
    ind++;
  }

  if((ind / 80) >= 24){
    // scroll up
    memmove(crt, crt + 80, sizeof(crt[0]) * (23 * 80));
    ind -= 80;
    memset(crt + ind, 0, sizeof(crt[0]) * ((24 * 80) - ind));
  }

  outb(crtport, 14);
  outb(crtport + 1, ind >> 8);
  outb(crtport, 15);
  outb(crtport + 1, ind);