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use crate::arch::x86_64::io_port::*;
const CGA_BUFFER_START:*mut u8 = 0xb8000 as *mut u8;
const IR_PORT:u16 = 0x3d4;
const DR_PORT:u16 = 0x3d5;
#[allow(dead_code)]
pub struct CGAScreen{
pub max_cows:u32,
pub max_rows:u32,
}
#[allow(dead_code)]
impl CGAScreen{
pub fn new(rows:u32, cols:u32) -> Self {
Self {max_rows:rows, max_cows:cols}
}
fn cal_offset(&self,row:u32, col:u32) -> u32{
col + row*self.max_cows
}
// this function should be the only one that "directly touches"
// the memory by address.
// and since it's unsafe, it shouldn't be public
pub fn show(&self, row:u32, col:u32, c:char, attr:u8){
let index = self.cal_offset(row, col);
unsafe{
*CGA_BUFFER_START.offset(index as isize * 2) = c as u8;
*CGA_BUFFER_START.offset(index as isize * 2 + 1) = attr;
}
}
// pub fn putchar(&self, ch:char){
//
// }
pub fn setpos(&self, row:u32, col:u32){
// io ports for instruction register and data register
let offset = self.cal_offset(row,col);
// set lower byte
outb(IR_PORT, 15 as u8);
outb(DR_PORT, offset as u8);
// set higher byte
outb(IR_PORT, 14 as u8);
outb(DR_PORT, (offset >> 8) as u8);
}
pub fn getoffset() -> u32 {
// read higher byte
outb(IR_PORT, 14 as u8);
let mut offset = inb(DR_PORT);
offset = offset << 8;
// read lower byte
outb(IR_PORT, 15 as u8);
offset += inb(DR_PORT);
offset as u32
}
pub fn getpos(&self, row:& mut u32, cow:& mut u32){
let offset = Self::getoffset();
*row = offset % self.max_cows;
*cow = offset / self.max_cows;
}
// Sanity Check of the cgascreen
pub fn test(&self){
let mut r = 0;
let mut c = 0;
let mut counter = 0;
while r<self.max_rows {
while c<self.max_cows {
let ch = (counter & 0xff) as u8;
self.show(r,c,ch as char, ch);
counter += 1;
c+=1;
}
r+=1;
c=0;
}
}
}
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