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menuentry "*****" {
        set root='(hd96)'
        set gfxpayload=1024x768x32
        multiboot /boot/kernel.bin
}

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        +-------------------+
0       | flags             |    (required)
        +-------------------+
4       | mem_lower         |    (present if flags[0] is set)
8       | mem_upper         |    (present if flags[0] is set)
        +-------------------+
12      | boot_device       |    (present if flags[1] is set)
        +-------------------+
16      | cmdline           |    (present if flags[2] is set)
        +-------------------+
20      | mods_count        |    (present if flags[3] is set)
24      | mods_addr         |    (present if flags[3] is set)
        +-------------------+
28 - 40 | syms              |    (present if flags[4] or
        |                   |                flags[5] is set)
        +-------------------+
44      | mmap_length       |    (present if flags[6] is set)
48      | mmap_addr         |    (present if flags[6] is set)
        +-------------------+
52      | drives_length     |    (present if flags[7] is set)
56      | drives_addr       |    (present if flags[7] is set)
        +-------------------+
60      | config_table      |    (present if flags[8] is set)
        +-------------------+
64      | boot_loader_name  |    (present if flags[9] is set)
        +-------------------+
68      | apm_table         |    (present if flags[10] is set)
        +-------------------+
72      | vbe_control_info  |    (present if flags[11] is set)
76      | vbe_mode_info     |
80      | vbe_mode          |
82      | vbe_interface_seg |
84      | vbe_interface_off |
86      | vbe_interface_len |
        +-------------------+
88      | framebuffer_addr  |    (present if flags[12] is set)
96      | framebuffer_pitch |
100     | framebuffer_width |
104     | framebuffer_height|
108     | framebuffer_bpp   |
109     | framebuffer_type  |
110-115 | color_info        |
        +-------------------+

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kmain()
{
        
}

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bits    32
section .text
   align 4
   
   dd 0x1BADB002
   dd 0x04
   dd -(0x1BADB002 + 0x04)
   
   dd 0 ; skip some flags
   dd 0
   dd 0
   dd 0
   dd 0
   
   dd 0 ; sets it to graphical mode
   dd 800 ; sets the width
   dd 600 ; sets the height
   dd 32 ; sets the bits per pixel
        
push ebx
global start
extern kmain
start:
        cli
        call kmain
        hlt

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bits    32
section .text
   align 4
   
   dd 0x1BADB002
   dd 0x04
   dd -(0x1BADB002 + 0x04)
   
   dd 0 ; skip some flags
   dd 0
   dd 0
   dd 0
   dd 0
   
   dd 0 ; sets it to graphical mode
   dd 800 ; sets the width
   dd 600 ; sets the height
   dd 32 ; sets the bits per pixel
       
global start
extern kmain
start:
    mov edi, dword [ebx + 88] ; edi <- framebuffer_addr
    mov dword [edi], 0x00FFFFFF ; white pixel should appear in top left corner
    mov esp, stack.end
    push ebx
    call kmain
    pop ebx
    cli
    hlt

stack: resb 4096
.end:

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vesa_clear();

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vesa_drawpixel(x,y,colour)

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typedef struct
{
    char skip[88];                // there are some interesting fields here but
	                               // we skip them for simplicity

    unsigned framebuffer_addr_lo; // separated these fields to avoid 64 bit
    unsigned framebuffer_addr_hi; // arithmetic (which may need some extra code)
    unsigned framebuffer_pitch;   // this is basically bytes per line
    unsigned framebuffer_width;
    unsigned framebuffer_height;
    unsigned char framebuffer_bpp;
} multiboot_info_t;

multiboot_info_t *mbinfo;

void vesa_drawpixel(unsigned x, unsigned y, unsigned color)
{   // assuming 32bpp
    unsigned *line = (unsigned *)(mbinfo->framebuffer_addr_lo + y * mbinfo->framebuffer_pitch);
    line[x] = color;
}

void vesa_clear(unsigned color)
{   // slow but simple
    for(unsigned y = 0; y < mbinfo->framebuffer_height; ++y)
    {
        for(unsigned x = 0; x < mbinfo->framebuffer_width; ++x)
            vesa_drawpixel(x, y, color);
    } 
}

void kmain(multiboot_info_t *mboot_info)
{
    mbinfo = mboot_info;
    vesa_clear(0x00203040);
    vesa_drawpixel(400, 300, 0x00FFFFFF);
}