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#define DEFN_SYSCALL1(fn,num,P1) \
int syscall_##fn(P1 p1) \
{ \
    int a; \
    asm volatile("int $0x80" : "=a"(a) : "0"(num), "b"((int)p1)); \
    return a; \
}

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DEFN_SYSCALL1(monitor_write, 0, char*);

static void *syscalls[3] =
{
    &monitor_write,
    &monitor_write_hex,
    &monitor_write_dec,
};

uint32_t num_syscalls = 3;

void initialize_syscalls()
{
    register_interrupt_handler(0x80, &syscall_handler);
}

void syscall_handler(registers_t *regs)
{
    if(regs->eax >= num_syscalls)
        return;

    void *location = syscalls[regs->eax];

    int ret;
    asm volatile (" \
     push %1; \
     push %2; \
     push %3; \
     push %4; \
     push %5; \
     call *%6; \
     pop %%ebx; \
     pop %%ebx; \
     pop %%ebx; \
     pop %%ebx; \
     pop %%ebx; \
    " : "=a"(ret) : "r"(regs->edi), "r" (regs->esi), "r" (regs->edx), "r" (regs->ecx), "r" (regs->ebx), "r" (location));
    regs->eax = ret;
}

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void switch_to_user_modes()
{
    uint32_t esp;
    asm volatile("mov %%esp, %0":"=r"(esp));
    set_kernel_stack(esp);
    //monitor_write_hex(cs);
    // Set up our kernel stack.
    //set_kernel_stack(current_task->kernel_stack+KERNEL_STACK_SIZE);

    // Set up a stack structure for switching to user mode.
    asm volatile("  \
      cli; \
      mov $0x23, %ax; \
      mov %ax, %ds; \
      mov %ax, %es; \
      mov %ax, %fs; \
      mov %ax, %gs; \
                    \
       \
      mov %esp, %eax; \
      pushl $0x23; \
      pushl %eax; \
      pushf; \
      pushl $0x1B; \
      push $1f; \
      iret; \
    1: \
      ");

      //enable_interrupts();
}

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int kernel_main(uint32_t magic, multiboot_t *mboot_ptr)
{
    init_gdt();
    init_idt();
    init_elf(mboot_ptr);

    printk_clear();

    //asm volatile("int $0x3");
    //init_timer(1);


    //0x100000  mboot_ptr->mem_upper
    init_pmm(0x400000);
    init_vmm();
    init_heap();
    init_memory(mboot_ptr);

    asm volatile("sti");

	switch_to_user_modes();
    syscall_monitor_write("Hello, user world!\n");
    return 0xDEADBEEF;
}