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Code: Select all

org 100h
bits 16

cli
 xor eax,eax
 mov ax,ds
 shl eax,4
 push eax

 pop eax
 mov ebx,GDT
 add eax,ebx
 mov [GDT+2],eax


  lgdt[GDT]                  ;{6}

    ;Set CR0's PE bit:
    ;Set CR0's PE bit:
      mov eax,cr0   ;{3}
      inc ax        ;{1}
      mov cr0,eax   ;{3}

push ds
push es
    ;Set 32-bit memory:
    ;Set 32-bit memory:
      push byte SELDat32 ;{2}
      pop ds             ;{1}
      push ds            ;{1}
      pop es             ;{1}



      dec ax       ;{1}
      mov cr0,eax  ;{3}

pop es
pop ds

sti


;;Set VESA mode:
;;;
mov ax,0x4F02
mov bx,0x4113  ;vesamode
int 10h

mov ax,0xA000
mov es,ax
mov di,di


mov ax,0x1234
mov cx,(65536/2)
;rep stosw


;;Get VESA mode info to get the LFB address:
;;;
;mov AX, 0x0050
mov ax,ds
mov ES, AX
;mov DI, 0x0000
mov di,ModeInfo
mov edi,ModeInfo
mov AX, 4F01h
mov CX, 0x4113  ;vesamode
int 10h



cli
a32 mov edx,dword[ds:edi+40]
a32 mov edx,dword[es:edi+40]
mov edx,dword[ds:di+40]
mov edx,dword[es:di+40]

;a32 mov edx,dword[0x500+40]
;mov ebp,0xDEADDEAD



mov ebp,edi
mov edi,edx
push edi


;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;mov edi,0xF0000000
mov ecx,((800*600*2)-1024)/4
push word 0
pop ds
push ds
pop es
mov eax,0x87654321
a32 rep stosd
;mov dword[edx],eax


pop edi




sti


;;Press a key to continue:
;;;
xor ah,ah
int 0x16


;;Return to DOS:
;;;
mov ah,0x4C
int 0x21




align 16
db "Signat1"
align 16
ModeInfo times 512 db 0
align 16
db "Signat2"
align 16


;;INIT: Data/Constants definitions and Arch. Structures
;;INIT: Data/Constants definitions and Arch. Structures
;;INIT: Data/Constants definitions and Arch. Structures
   ;INIT: GDT
   ;INIT: GDT
   ;INIT: GDT
     GDT:
      SELNull equ 0    ;As you may see, we have used
        GDT_size:      ;the Null Selector as the GDT
          dw GDTsize   ;pointer to load with LGDT.
        GDT_actualPtr: ;
          dd GDT       ;You can see that the WORD at
          dw 0x0000    ;the end of these 8 bytes are
                       ;2 padding bytes with 0x0000.

      SELCod32 equ 8
        dw 0FFFFh       ; bits 0-15 length (Bytes 0-1)
        dw 00000h       ; bits 0-15 base addr (Bytes 2-3)
        db 0            ; bits 16-23 base addr (Byte 4)
        db 10011010b    ; bits 0-3 Type, 4 DT, 5-6 DPL & 7 P (Byte 5)
        db 11001111b    ; bits 16-19 length into 0-3, 6 D & 7 G (Byte 6)
        db 0            ; bits 24-31 base addr (Byte 7)

      SELDat32 equ 16
        dw 0FFFFh       ; bits 0-15 length (Bytes 0-1)
        dw 00000h       ; bits 0-15 base addr (Bytes 2-3)
        db 0            ; bits 16-23 base addr (Byte 4)
        db 10010010b    ; bits 0-3 Type, 4 DT, 5-6 DPL & 7 P (Byte 5)
        db 11001111b    ; bits 16-19 length into 0-3, 6 D & 7 G (Byte 6)
        db 0            ; bits 24-31 base addr (Byte 7)
      GDT_end:

      GDTsize equ (GDT_end-GDT)-1
   ;END:  GDT
   ;END:  GDT
   ;END:  GDT
;;END:  Data/Constants definitions and Arch. Structures
;;END:  Data/Constants definitions and Arch. Structures
;;END:  Data/Constants definitions and Arch. Structures

Code: Select all

;File: boot2.s

	;return vga mode info function
	mov ax,0x4f01          
	mov cx,0x103              ;800x600x8bpp 
	mov di, vgamodeinfoblock  ;bios will write to this memory
	int 10h                   ;call bios