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#include "u.h"
#include "lib.h"
#include "mem.h"
#include "dat.h"
#include "fns.h"
enum {
Width = 160,
Height = 25,
Attr = 7, /* white on black */
};
#define CGASCREENBASE ((uchar*)KADDR(0xB8000))
static int pos;
static int screeninitdone;
static uchar
cgaregr(int index)
{
outb(0x3D4, index);
return inb(0x3D4+1) & 0xFF;
}
static void
cgaregw(int index, int data)
{
outb(0x3D4, index);
outb(0x3D4+1, data);
}
static void
movecursor(void)
{
cgaregw(0x0E, (pos/2>>8) & 0xFF);
cgaregw(0x0F, pos/2 & 0xFF);
CGASCREENBASE[pos+1] = Attr;
}
static void
cgascreenputc(int c)
{
int i;
if(c == '\n'){
pos = pos/Width;
pos = (pos+1)*Width;
}
else if(c == '\t'){
i = 8 - ((pos/2)&7);
while(i-->0)
cgascreenputc(' ');
}
else if(c == '\b'){
if(pos >= 2)
pos -= 2;
cgascreenputc(' ');
pos -= 2;
}
else{
CGASCREENBASE[pos++] = c;
CGASCREENBASE[pos++] = Attr;
}
if(pos >= Width*Height){
memmove(CGASCREENBASE, &CGASCREENBASE[Width], Width*(Height-1));
memset(&CGASCREENBASE[Width*(Height-1)], 0, Width);
pos = Width*(Height-1);
}
movecursor();
}
static void
screeninit(void)
{
if(screeninitdone == 0){
pos = cgaregr(0x0E)<<8;
pos |= cgaregr(0x0F);
pos *= 2;
screeninitdone = 1;
}
}
void
cgascreenputs(char* s, int n)
{
if(screeninitdone == 0)
screeninit();
while(n-- > 0)
cgascreenputc(*s++);
}
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