ferglos/src/kernel.cpp

/* 
 *  kernel.cpp 
 *  Author: Fergal Moran
 *  Copyright: 2020 Fergal Moran
 *  
 *  BSD License - do what you want
 */

#include "../include/gdt.h"
#include "../include/interrupts.h"
#include "../include/types.h"

void printf(char* str) {
    static uint16_t* VideoMemory = (uint16_t*)0xb8000;
    static uint8_t x = 0, y = 0;

    for (int i = 0; str[i] != '\0'; ++i) {
        switch (str[i]) {
            case '\n':
                y++;
                x = 0;
                break;
            default:
                VideoMemory[80 * y + x] = (VideoMemory[80 * y + x] & 0xFF00) | str[i];
                x++;
                break;
        }

        //line feed after 80 chars (terminal width)
        if (x >= 80) {
            y++;
            x = 0;
        }
        //we've reached max screen rows
        if (y > 25) {
            for (y = 0; y < 25; y++) {
                for (x - 0; x < 80; x++) {
                    VideoMemory[80 * y + x] = (VideoMemory[80 * y + x] & 0xFF00) | ' ';
                }
            }
        }
    }
}

typedef void (*constructor)();
extern "C" constructor start_ctors;
extern "C" constructor end_ctors;
extern "C" void call_constructors() {
    for (constructor* i = &start_ctors; i != &end_ctors; i++)
        (*i)();
}

extern "C" void ferglos_Main(const void* multiboot_structure, uint32_t /*mb_mag*/) {
    printf("Welcome to FerglOS v0.0.2!\n");
    printf("Hitler blinks.");

    GlobalDescriptorTable gdt;
    InterruptManager interrupts(&gdt);

    //instantiate hardware in here somewhere

    interrupts.Activate();

    while (1)
        ;
}