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MBALIGN  equ  1 << 0            ; align loaded modules on page boundaries
MEMINFO  equ  1 << 1            ; provide memory map
VIDINFO  equ 1 << 2
FLAGS    equ  MBALIGN | MEMINFO | VIDINFO ; this is the Multiboot 'flag' field
MAGIC    equ  0x1BADB002        ; 'magic number' lets bootloader find the header
CHECKSUM equ -(MAGIC + FLAGS)   ; checksum of above, to prove we are multiboot


section .multiboot
align 4
	dd MAGIC
	dd FLAGS
	dd CHECKSUM

  dd 0,0,0,0,0
  dd 0
  dd 640, 480, 8

section .bss
align 16
stack_bottom:
resb 16384 ; 16 KiB
stack_top:

; The linker script specifies _start as the entry point to the kernel and the
; bootloader will jump to this position once the kernel has been loaded. It
; doesn't make sense to return from this function as the bootloader is gone.
; Declare _start as a function symbol with the given symbol size.
section .text
global _start:function (_start.end - _start)
_start:
  mov esp, stack_top
  cli
  push ebx
  extern kmain
  call kmain

	cli
.hang:	hlt
	jmp .hang
.end:

Code: Select all

void putpixel(int color, int x , int y) {
  unsigned int *pixel = (unsigned int*) 0xA0000 + y * 640 + x;
  *pixel = color;
}

void cls_graph() {
  for (int r = 0; r < 480; r++) {
    for (int c = 0; c < 640; c++) {
      putpixel (BLUE, c, r);
    }
  }
}

Code: Select all

mov ax, 0  ;segment 0
mov es, ax
mov di, 0x1000  ;offset 1000
mov ax, 0x4F01  ;get VBE mode information block
mov cx, 0x4114  ;graphic mode 800x600 16 bpp
int 0x10  ;load informations

;set VESA video mode
mov ax, 0x4F02  ;set VBE graphic mode
mov bx, 0x4114  ;graphic mode 800x600 16bpp
int 0x10  ;start BIOS interrupt

Code: Select all

void read_vesa_info(void) {
  uint32_t *vesablockd = (uint32_t *) 0x1000;  //position of Vesa Mode Info Block loaded by bootloader dword read
  uint16_t *vesablockw = (uint16_t *) 0x1000;  //position of Vesa Mode Info Block loaded by bootloader word read
  uint8_t *vesablockb = (uint8_t *) 0x1000;  //position of Vesa Mode Info Block loaded by bootloader byte read
  vesa_lfb=vesablockd[10];  //Linear Frame Buffer position
  vesa_x=vesablockw[9];
  vesa_y=vesablockw[10];
  vesa_bpp=vesablockb[23];
}
//putpixel function
void pixel(int line, int column, uint16_t color) {
    uint16_t *pixel = (uint16_t*) vesa_lfb + line * vesa_x + column;  //start of frame buffer
    pixel = color;
}

Code: Select all

static const int a_ch[128] = {
0,0,0,0,0,0,0,0,
0,0,0,0,0,0,0,0,
0,0,0,0,0,0,0,0,
0,0,0,1,0,0,0,0,
0,0,1,1,1,0,0,0,
0,1,1,0,1,1,0,0,
1,1,0,0,0,1,1,0,
1,1,0,0,0,1,1,0,
1,1,1,1,1,1,1,0,
1,1,0,0,0,1,1,0,
1,1,0,0,0,1,1,0,
1,1,0,0,0,1,1,0,
1,1,0,0,0,1,1,0,
0,0,0,0,0,0,0,0,
0,0,0,0,0,0,0,0,
0,0,0,0,0,0,0,0,
};

//zeros are blacks, ones are white
for (int r = line; r < line + 16; r++) {
        for (int c = column; c < column + 8; c++) {
          if (a_ch[index] == 0) pixel(r, c, WHITE);
          if (a_ch[index] == 1) pixel(r, c, BLACK);
          index++;
        }
      }
      col+=8;