1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
|
__asm__(".code16gcc\n");
void vga_graphics_write_at_offset(char, short);
void vga_graphics_write(char);
void vga_graphics_write_with_attr(char, char);
void vga_graphics_write_str(char*);
static short CURSOR_LOC = 0;
void _start() {
vga_graphics_write_with_attr('a', 1);
vga_graphics_write_with_attr('/', 2);
vga_graphics_write_with_attr('b', 3);
char foo[] = "hello how are you";
vga_graphics_write_str(foo);
while(1) { }
}
void vga_graphics_write_str(char* str) {
while(*str) {
vga_graphics_write(*str++);
}
}
void vga_graphics_write_with_attr(char value, char attr) {
vga_graphics_write_at_offset(value, CURSOR_LOC++);
vga_graphics_write_at_offset(attr, CURSOR_LOC++);
}
void vga_graphics_write(char value) {
vga_graphics_write_at_offset(value, CURSOR_LOC);
CURSOR_LOC += 2;
}
void vga_graphics_write_at_offset(char value, short offset) {
__asm__(
"mov %0, %%al \n"
"mov %1, %%di \n"
"mov %%al, %%gs:(%%di) \n"
: :"r"(value), "r"(offset) : "%ax", "%di");
}
|
