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#include <lib.h>
#include <comus/drivers/tty.h>
#include <comus/asm.h>
#include <comus/memory.h>
#define VGA_ADDR 0xB8000
static const uint8_t width = 80;
static const uint8_t height = 25;
static volatile uint16_t *buffer = (uint16_t *)VGA_ADDR;
// position
static uint32_t x = 0, y = 0;
// color
static uint8_t fg = 15, bg = 0;
// blank color
const uint16_t blank = (uint16_t)0 | 0 << 12 | 15 << 8;
static void term_clear_line(int line)
{
if (line < 0 || line >= height)
return;
for (uint8_t x = 0; x < width; x++) {
const size_t index = line * width + x;
buffer[index] = blank;
}
}
static void term_clear(void)
{
for (uint8_t y = 0; y < height; y++)
term_clear_line(y);
}
static void term_scroll(int lines)
{
cli();
y -= lines;
if (!lines)
return;
if (lines >= height || lines <= -height) {
term_clear();
} else if (lines > 0) {
memmovev(buffer, buffer + lines * width, 2 * (height - lines) * width);
term_clear_line(height - lines);
} else {
memmovev(buffer + lines * width, buffer + lines,
(height + lines) * width);
}
sti();
}
void tty_out(char c)
{
if (buffer == NULL)
return;
// handle special chars
switch (c) {
case '\n':
x = 0;
y++;
break;
case '\t':
x += 4;
break;
case '\v':
case '\f':
y++;
break;
case '\r':
x = 0;
break;
default: {
const size_t index = y * width + x;
buffer[index] = c | bg << 12 | fg << 8;
x++;
}
}
// wrap cursor if needed
if (x >= width) {
x = 0;
y++;
}
if (y >= height) {
term_scroll(y - (height - 1));
y = height - 1;
}
// set cursor position on screen
const uint16_t pos = y * width + x;
outb(0x3D4, 0x0F);
outb(0x3D5, (uint8_t)(pos & 0xFF));
outb(0x3D4, 0x0E);
outb(0x3D5, (uint8_t)((pos >> 8) & 0xFF));
}
void tty_out_str(const char *str)
{
while (*str)
tty_out(*str++);
}
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