macro align value { rb (value-1)-($+value-1) mod value }
org 100h
mov ax,cs
mov ds,ax
mov es,ax
xor eax,eax
mov ax,cs;cs?????????
shl eax,4;?????????
add [gdtptr+2],eax
; add eax,disppmmsg
mov word [gdt+10],ax
shr eax,16
mov byte [gdt+12],al
mov byte [gdt+15],ah
lgdt [gdtptr]
cli
in al, 92h
or al, 00000010b
out 92h, al
mov ds,[gdt];0
mov eax, cr0
or eax, 1
mov cr0, eax
jmp dword 8:disppmmsg ;codeselector
;??GDT
align 16
gdt:
dw 0,0,0,0
dw 0xffff
dw 0x0000;???/? 10
dw 0x9A00;??????? 12
dw 0x00C0; 14
dw 0xffff
dw 0x8000;??/?
dw 0x920B;?????0x0B8000
dw 0x00C0
codeselector equ 0x08
videoselector equ 0x10
;GDTR
gdtptr:
dw 0x0010
dw gdt,0
use32
disppmmsg:
; xor ebx,ebx
; mov ax,es
; mov bx,$b810
; sub bx,ax
; shl ebx,4
;mov ax,16
;mov ds,ax
mov [$b8000],byte 'A'
jmp $
mov ax,videoselector
mov gs,ax
mov edi,(80*0+0)*2;?????????,????????
mov ah,0x0c;??????
mov al,'S';??????
mov [gs:edi],ax
mov edi,(80*0+1)*2
mov ah,0x0c
mov al,'u'
mov [gs:edi],ax
mov edi,(80*0+2)*2
mov ah,0x0c
mov al,'n'
mov [gs:edi],ax
jmp $
If I use MOV DS,xxx before MOV [$B8000],x it crashes.Why?[/code]
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> OS Construction > All kinds of error when MOVing in 32-bit mode
15 Jan 2015, 08:56
