fbc -c kernel.bas -o kernel.o

ld -T link.ld -o kernel.bin kernel.o

grub-mkrescue -o FbOS.iso isodir

qemu -hda FbOS.iso -m 32

OUTPUT_FORMAT("elf32-i386")
ENTRY (loader)

SECTIONS{
     . = 0x00100000;

     .text :{
         KERNEL_START = .;

         *(.text)
     }

     .rodata ALIGN (0x1000) : {
         *(.rodata)
         _CTORS = .;
         *(.ctors)
         _CTORS_END = .;        
     }

     .data ALIGN (0x1000) : {
         *(.data)
     }

     .bss : {
         SBSS = .;
         *(COMMON)
         *(.bss)
         EBSS = .;

         KERNEL_END = .;
     }
}

Extern "C"
Declare SUB PrintString(src AS Byte Ptr, x AS LONG, y AS LONG)
DECLARE SUB main ()
DECLARE Sub multiboot ()

Sub multiboot ()
    Asm
      'setting up the Multiboot header - see GRUB docs for details
      .set ALIGN,    1<<0              
      .set MEMINFO,  1<<1              
      .set FLAGS,    ALIGN | MEMINFO   
      .set MAGIC,    0x1BADB002        
      .set CHECKSUM, -(MAGIC + FLAGS)  
      .align 4
      .LONG MAGIC
      .LONG FLAGS
      .LONG CHECKSUM
      .set STACKSIZE, 0x4000           
      .comm stack, STACKSIZE, 32       
      .global loader                    
      loader:
        lea   esp, stack + STACKSIZE
        push  eax                        
        push  ebx                        
   
        CALL  MAIN
   
        cli
        hlt                     
    END Asm
End Sub
Sub main ()
     CONST s = "FreeBasic OS from Bare Bones"
     PrintString CPtr(Byte Ptr, @s), 26, 12
End Sub
Sub PrintString(src AS Byte Ptr, x AS LONG, y AS LONG)
     DIM dst AS Byte Ptr
     Dim bColor As Byte
     bColor = 1
     DIM counter AS Long
     dst = CPtr(Byte Ptr, &HB8000 + y * 160 + x * 2)
     counter = 0
     WHILE src[counter] <> 0
         dst[2 * counter] = src[counter]
         dst[2 * counter + 1] = bColor
         counter = counter + 1
         bColor=bColor+1
         If bColor = 16 Then bColor = 1
     WEND
END Sub
End Extern