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__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*);
void vga_graphics_byte_hex(char);
//void vga_graphics_short_hex(short);
//void vga_graphics_int_hex(int);
//void vga_graphics_long_hex(long);
void clear();
static short CURSOR_LOC = 0;
static char* HEX_CHARS = "0123456789abcdef";
char foo[] = "hello how are you";
void _start() {
clear();
vga_graphics_write_with_attr('a', 1);
vga_graphics_write_with_attr('/', 2);
vga_graphics_write_with_attr('b', 3);
vga_graphics_write_str(foo);
vga_graphics_write(':');
vga_graphics_write(' ');
vga_graphics_byte_hex(0x40);
while(1) { }
}
void clear() {
int TERM_WIDTH = 80;
int TERM_HEIGHT = 25;
int i = 0;
while(i < TERM_WIDTH * TERM_HEIGHT) {
vga_graphics_write_with_attr(' ', 7);
i++;
}
CURSOR_LOC = 0;
}
void vga_graphics_write_str(char* str) {
while(*str) {
vga_graphics_write_with_attr(*str++, 7);
}
}
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_byte_hex(char value) {
char low = value & 0x0f;
char high = (value & 0xf0) >> 4;
vga_graphics_write(HEX_CHARS[high]);
vga_graphics_write(HEX_CHARS[low]);
}
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");
}
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