kernel/kernel.c

#include "multiboot.h"
#include "vga.h"

static inline void outb(unsigned short port, unsigned char val) {
  asm volatile ("outb %0, %1" : : "a"(val), "Nd"(port) : "memory");
}

char* itoa(int value, int base) {
    char* result;

    // check that the base if valid
    if (base < 2 || base > 36) { *result = '\0'; return result; }

    char* ptr = result, *ptr1 = result, tmp_char;
    int tmp_value;

    do {
        tmp_value = value;
        value /= base;
        *ptr++ = "zyxwvutsrqponmlkjihgfedcba9876543210123456789abcdefghijklmnopqrstuvwxyz" [35 + (tmp_value - value * base)];
    } while ( value );

    // Apply negative sign
    if (tmp_value < 0) *ptr++ = '-';
    *ptr-- = '\0';
    while(ptr1 < ptr) {
        tmp_char = *ptr;
        *ptr--= *ptr1;
        *ptr1++ = tmp_char;
    }
    return result;
}

void kmain (unsigned int mbootmagick, multiboot_info_t* mbootinfo) {

    // Cursor disabling
    outb(0x3D4, 0x0A);
    outb(0x3D5, 0x20);

    //cls();
    vga_init(VGA_COLOR_BLACK, VGA_COLOR_GRAY);

    vga_write_line("=== KoalemOS ===");
    vga_write("Checking multiboot loader: ");

    // Check multiboot header
    if (mbootmagick != MULTIBOOT_BOOTLOADER_MAGIC) {
        vga_write_color("INVALID MAGIC", VGA_COLOR_BLACK, VGA_COLOR_RED);
        return;
    }
    if (mbootinfo->flags & MULTIBOOT_INFO_BOOT_LOADER_NAME)
        vga_write((char *)mbootinfo->boot_loader_name);
    else
        vga_write_color("Unknown", VGA_COLOR_BLACK, VGA_COLOR_ORANGE);

    vga_write("\nMultiboot flags: ");
    vga_write(itoa(mbootinfo->flags, 2));

    // Check videomode
    vga_write("\nVideomode: ");

    if (mbootinfo->flags & MULTIBOOT_INFO_VBE_INFO) {
        vga_write("VBE 0x");
        vga_write(itoa(mbootinfo->vbe_mode, 16));
    } else if (mbootinfo->flags & MULTIBOOT_INFO_FRAMEBUFFER_INFO) {
        vga_write("Framebuffer");
        vga_write("\nVideo address: 0x");
        vga_write(itoa(mbootinfo->framebuffer_addr, 16));
        unsigned long long *vmem = &mbootinfo->framebuffer_addr;
        *vmem = 0xff00ff;

    } else {
        vga_write_color("Not available", VGA_COLOR_BLACK, VGA_COLOR_RED);
        return;
    }

    vga_write_line("\nExecution finished, halting...");
    *(unsigned char *)0xb8000 = '!';
}