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#pragma once

/* Multiboot header magic number */ 
#define MULTIBOOT_HEADER_MAGIC			0x1BADB002
/* Multiboot info magic number  */
#define MULTIBOOT_BOOTLOADER_MAGIC      0x2BADB002

#define MULTIBOOT_HEADER_FLAGS			0x00010003
#define STACK_SIZE						0x4000    
#define CHECKSUM						-(MULTIBOOT_HEADER_MAGIC + MULTIBOOT_HEADER_FLAGS)

#define CHECK_FLAG(flags,bit)			((flags) & (1 << (bit)))

/* The Multiboot header. */
typedef struct multiboot_header
{
	unsigned long magic;
	unsigned long flags;
	unsigned long checksum;
	unsigned long header_addr;
	unsigned long load_addr;
	unsigned long load_end_addr;
	unsigned long bss_end_addr;
	unsigned long entry_addr;
	unsigned long mode_type;
	unsigned long width;
	unsigned long height;
	unsigned long depth;
} multiboot_header_t;


/* The symbol table for a.out. */
typedef struct aout_symbol_table
{
	unsigned long tabsize;
	unsigned long strsize;
	unsigned long addr;
	unsigned long reserved;
} aout_symbol_table_t;

/* The section header table for ELF. */
typedef struct elf_section_header_table
{
	unsigned long num;
	unsigned long size;
	unsigned long addr;
	unsigned long shndx;
} elf_section_header_table_t;

/* The Multiboot information. */
typedef struct multiboot_info
{
	unsigned long flags;
	unsigned long mem_lower;
	unsigned long mem_upper;
	unsigned long boot_device;
	unsigned long cmdline;
	unsigned long mods_count;
	unsigned long mods_addr;
	union
	{
		aout_symbol_table_t aout_sym;
		elf_section_header_table_t elf_sec;
	} u;
	unsigned long mmap_length;
	unsigned long mmap_addr;
	unsigned long drives_length;
	unsigned long drives_addr;
	unsigned long config_table;
	unsigned long boot_loader_name;
	unsigned long apm_table;
	unsigned long vbe_control_info;
	unsigned long vbe_mode_info;
	unsigned long vbe_mode;
	unsigned long vbe_interface_seg;
	unsigned long vbe_interface_off;
	unsigned long vbe_interface_len;
} multiboot_info_t;

/* The module structure. */
typedef struct module
{
	unsigned long mod_start;
	unsigned long mod_end;
	unsigned long string;
	unsigned long reserved;
} module_t;

/* The memory map. Be careful that the offset 0 is base_addr_low
but no size. */
typedef struct memory_map
{
	unsigned long size;
	unsigned long base_addr_low;
	unsigned long base_addr_high;
	unsigned long length_low;
	unsigned long length_high;
	unsigned long type;
} memory_map_t;

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#include <multiboot.h>

// declarations
void kernel_Startup( multiboot_header* header );
void kernel_main(unsigned long magic, unsigned long addr);



/*  This is the one of most important thing to be able to load a PE kernel
with GRUB. Because PE header are in the begining of the file, code section
will be shifted. The value used to shift the code section is the linker 
align option /ALIGN:value. Note the header size sum is larger than 512,
so ALIGN value must be greater */
#define	ALIGN					0x400

/*	Must be >= 1Mo for GRUB
Base adress from advanced linker option */
#define LOADBASE				0x100000

/*	PE header are stored at the beginning of the file.
Code section is placed after */
#define	HEADER_ADDRESS			LOADBASE+ALIGN


/*************************************************************
* MULTIBOOT Header
* These data are placed at the beginning of the kernel file
* Grub 2 needs these data to boot properly
* see multiboot specification
*************************************************************/
#pragma code_seg(".a$0")
__declspec(allocate(".a$0"))
multiboot_header _MultibootHeader = {

   MULTIBOOT_HEADER_MAGIC,
   MULTIBOOT_HEADER_FLAGS,
   CHECKSUM,
   HEADER_ADDRESS,
   LOADBASE,
   0, //load end address
   0, //bss end address
   (unsigned long)DNA_Startup,
   0,
   800,
   600,
   8
};
#pragma comment(linker, "/merge:.text=.a")


/*************************************************************
* kernel_Startup 
* this function is referenced by multiboot header to let 
* Grub 2 start operating system 
*************************************************************/
void kernel_Startup( multiboot_header* header ) {

	unsigned long magic;
	unsigned long multibootInfoPointer;
	
	/* set parameters */
	__asm {
		mov	magic, eax
		mov multibootInfoPointer, ebx
	}

	/* Start operating system */
	if (magic == 0x2BADB002)
	{
		kernel_main(magic, multibootInfoPointer);
	}

	// just stop if not loaded by Grub
	_asm hlt;
}


/*************************************************************
* kernel_main 
* The main entry for   
* let Grub 2 start operating system 
*************************************************************/
void kernel_main(unsigned long magic, unsigned long addr) {

	char *sHello = "Hello from GRUB2 !\0";
	char *videoMemory= (char*)(0xB8000);
	char color= 0xF0;

	// erase screen
	for(int i=0; i< 80*25; i++)
	{
		*videoMemory++ = ' ';		// character value
		*videoMemory++ = 0x00;		// color value
	}

	videoMemory= (char*)(0xB8000);  // reset video memory pointer

	// display message
	while (*sHello!='\0')
	{
		*videoMemory++ = *sHello++;	// character value
		*videoMemory++ = color;		// color value
	}	
	_asm hlt;						// stop to not hang on
}

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set timeout=0
set default=0 # Set the default menu entry
 
menuentry "MY_OPERATING_SYSTEM"
{
   multiboot /boot/MYKERNEL_NAME   # The multiboot command replaces the kernel command
}

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@SET KernelFile=PATH_TO_YOUR_KERNEL_YOU_HAVE_CREATED_WITH_VS2010
@SET ISOImageName=PATH_TO_YOUR_ISOFILE_YOU_WANT_TO_CREATE
@SET GrubFile=PATH_TO_THE_FOLDER_WHERE_IS_BOOT_FOLDER

Echo Build iso image with Grub 1.98
xcopy %KernelFile% %GrubFile%\boot\MYKERNEL_NAME /Y
sh grub-mkrescue --output=%ISOImageName% %GrubFile%
pause