GitFOSS

#include "system/common.hpp"

void hide_cursor() {
    asm volatile (
        "movw $0x3D4, %%dx\n"   // select cursor start register
        "movb $0, %%al\n"
        "outb %%al, %%dx\n"
        "movw $0x3D5, %%dx\n"   // select cursor end register
        "movb $0, %%al\n"
        "outb %%al, %%dx\n"
        :
        :
        : "dx", "al"
    );
}

typedef unsigned short uint16_t;
typedef unsigned char uint8_t;

static inline void outb(uint16_t port, uint8_t val) {
    __asm__ volatile ("outb %0, %1" : : "a"(val), "Nd"(port));
}

void set_cursor_position(int row, int col) {
	  unsigned short position = 80 * row + col;
    // Write the high byte
    outb(0x3D4, 0x0E);
    outb(0x3D5, (position >> 8) & 0xFF);

    // Write the low byte
    outb(0x3D4, 0x0F);
    outb(0x3D5, position & 0xFF);
}

void clear_screen() {
    volatile char* video_memory = (char*)0xB8000;
    const int screen_size = 80 * 25; // 80 columns x 25 rows
    for (int i = 0; i < screen_size; ++i) {
        video_memory[2*i] = ' ';        // Character space
        video_memory[2*i + 1] = 0x07;   // Attribute (white on black)
    }
}

void print_string(const char* str) {
    volatile char* video_memory = (char*)0xB8000;
    int i = 0;
    while (str[i] != '\0') {
        video_memory[2*i] = str[i];     // Character space
        video_memory[2*i + 1] = 0x07;   // Attribute (white on black)
        i++;
    }
}

extern "C" void kmain()
{
	u8* address = (u8*) 0xb8000;
	const u8* string = "[CrystalOS Kernel] Hello from C++";
	u16 stringSize = 33;
	
	clear_screen();
	set_cursor_position(1, 0);
	hide_cursor();

	for (u16 i = 0; i < stringSize; i++)
	{
		*address = (u8) string[i];
		address += 1;
		*address = (u8) 0xA0;
		address += 1;
	}

	while (true);
}