#include "exception.h"
#include "gdt.h"
#include "idt.h"
#include "interrupt.h"
#include "io.h"
#include "irq.h"
#include "mem.h"
#include "multiboot.h"
#include "pit.h"
#include "types.h"
#include "vga.h"

#define CHECK_FLAG(flags,bit)   ((flags) & (1 << (bit)))
void cpuid(int code, uint32_t *a, uint32_t *d)
{
    asm volatile("cpuid" : "=a"(*a), "=d"(*d) : "0"(code) : "ebx", "ecx");
}


// Multiboot information available here : https://www.gnu.org/software/grub/manual/multiboot/multiboot.html#kernel_002ec
void kmain(unsigned long magic, unsigned long addr)
{
    unsigned long upper_mem = 0;
    initVGA(BLACK, GREEN);
    printString("Setting up IDT\n");
    gdtSetup();
    idtSetup();
    irqSetup();
    initPit(100);

    if (magic == MULTIBOOT_BOOTLOADER_MAGIC) { // Get loaded by Grub wuth mutliboot version 1
        multiboot_info_t *mbi = (multiboot_info_t *)addr;
        /* Are mem_* valid? */
        if (CHECK_FLAG(mbi->flags, 0)){
            printString("mem_lower = ");
            printInt((unsigned)mbi->mem_lower);
            printString("KB mem_upper = ");
            printInt((unsigned)mbi->mem_upper);
            printString("KB\n");
            upper_mem = mbi->mem_upper;
        }

        /* Is boot_device valid? */
        if (CHECK_FLAG(mbi->flags, 1)){
            printString("boot_device = ");
            printInt((unsigned)mbi->boot_device);
            printString("\n");
        }

        /* Is the command line passed? */
        if (CHECK_FLAG(mbi->flags, 2)){
            printString("cmdline = ");
            printString((char *)mbi->cmdline);
            printString("\n");
        }
    }

    if(upper_mem == 0){
        printString("Cannot get upper phy mem bound. Using default value 32MB\n");
        upper_mem = 32 * 1024;
    }
    memInit(upper_mem);

    printString("Setting up IRQ handlers\n");
    irqSetRoutine(IRQ_KEYBOARD, keyboard_handler);
    irqSetRoutine(IRQ_TIMER, timer_handler);
    printString("Enabling HW interrupts\n");
    exceptionSetRoutine(EXCEPTION_DOUBLE_FAULT, print_handler);
    // Enabling the HW interrupts
    asm volatile("sti\n");
    int count = 0;
    while (1) {
        printIntDetails(count++, GREEN, BLACK, 0, VGA_HEIGHT - 1);
    }
    printString("exiting\n");
}