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#include <nrvn.h>
#include <vga.h>
static size_t vga_x, vga_y;
static uint8_t vga_color;
static uint16_t *vga_buffer;
void vga_init(void) {
vga_x = vga_y = 0;
vga_set_color(VGA_LIGHT_MAGENTA, VGA_BLACK);
vga_buffer = (uint16_t *)0xB8000;
for (size_t y = 0; y < VGA_HEIGHT; y++)
for (size_t x = 0; x < VGA_WIDTH; x++)
vga_buffer[y * VGA_WIDTH + x] = ' ' | (vga_color << 8);
}
void vga_scroll() {
if (vga_y < VGA_HEIGHT)
return;
for (size_t y = 0; y < VGA_HEIGHT - 1; y++) {
for (size_t x = 0; x < VGA_WIDTH; x++) {
const size_t from = (y + 1) * VGA_WIDTH + x;
const size_t to = y * VGA_WIDTH + x;
vga_buffer[to] = vga_buffer[from];
}
}
vga_y = VGA_HEIGHT - 1;
for (size_t x = 0; x < VGA_HEIGHT; x++) {
vga_buffer[vga_y * VGA_WIDTH + x] = ' ' | (vga_color << 8);
}
}
void vga_update_cursor(void) {
size_t index = vga_y * VGA_WIDTH + vga_x;
outb(0x3D4, 14);
outb(0x3D5, index >> 8);
outb(0x3D4, 15);
outb(0x3D5, index);
}
void vga_putn(const size_t number) {
char digits[32] = { 0 };
size_t num = number, count = 0;
do {
digits[count] = (num % 10) + '0';
count++;
} while ((num /= 10) > 0);
do {
vga_putc(digits[count]);
} while (count-- > 0);
}
void vga_putx(const size_t hex) {
char digits[32] = { 0 };
size_t num = hex, count = 0;
do {
digits[count] = "0123456789abcdef"[num % 16];
count++;
} while ((num /= 16) > 0);
vga_puts("0x");
do {
vga_putc(digits[count]);
} while (count-- > 0);
}
void vga_putc(const char c) {
switch (c) {
case '\n':
vga_x = 0;
vga_y++;
break;
case '\b':
if (vga_x > 0)
vga_x--;
break;
case '\r':
vga_x = 0;
break;
case '\t':
break;
default:
// Any character greater than and including a space, is a printable character
if (c >= ' ')
vga_buffer[vga_y * VGA_WIDTH + vga_x++] = (uint16_t) c | ((uint16_t) vga_color << 8);
}
if (vga_x >= VGA_WIDTH) {
vga_x = 0;
vga_y++;
}
vga_scroll();
vga_update_cursor();
}
void vga_puts(const char *s) {
while (*s)
vga_putc(*s++);
}
void vga_putsn(const char *s, const size_t len) {
for (size_t i = 0; i < len; i++)
vga_putc(s[i]);
}
void vga_set_color(const uint8_t fg, const uint8_t bg) {
vga_color = fg | bg << 4;
}
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