pm.inc
%macro Descriptor 3
dw %2 & 0FFFFh
dw %1 & 0FFFFh
db (%1 >> 16) & 0FFh
dw ((%2 >> 8) & 0F00h) | (%3 0F0FFh)
db (%1 >> 24) & 0FFh
%endmacropmtest1.asm
%include "pm.inc"
org 07c00h
jmp LABEL_BEGIN
[SECTION .gdt]
; 段基址，段界限，屬性（段界限 2bytes, 段基址 4bytes）
LABEL_GDT: Descriptor 0, 0, 0
LABEL_DESC_CODE32: Descriptor 0, SegCode32Len - 1, DA_C + DA_32
LABEL_DESC_VIDEO: Descriptor 0B8000h, 0ffffh, DA_DRW
GdtLen equ $ - LABEL_GDT
GdtPtr dw GdtLen - 1
dd 0
SelectorCode32 equ LABEL_DESC_CODE32 - LABEL_GDT
SelectorVideo equ LABEL_DESC_VIDEO - LABEL_GDT
[SECTION .s16]
[BITS 16]
LABEL_BEGIN:
mov ax, cs
mov ds, ax
mov es, ax
mov ss, ax
mov sp, 0100h
xor eax, eax
mov ax, cs
shl eax, 4
add eax, LABEL_SEG_CODE32
mov word [LABEL_DESC_CODE32 + 2], ax
shr eax, 16
mov byte [LABEL_DESC_CODE32 + 4], al
mov byte [LABEL_DESC_CODE32 + 7], ah
xor eax, eax
mov ax, ds
shl eax, 4
add eax, LABEL_GDT
mov dword [GdtPtr + 2], eax
lgdt [GdtPtr]
cli
in al, 92h
or al, 00000010b
out 92h, al
mov eax, cr0
or eax, 1
mov cr0, eax
jmp dword SelectorCode32:0
[SECTION .s32]
[BITS 32]
LABEL_DESC_CODE32:
mov ax, SelectorVideo
mov gs, ax
mov edi, (80 * 11 + 79) * 2
mov ah, 0ch
mov al, 'p'
jmp $
SegCode32Len equ $ - LABEL_SEG_CODE32