?? pm4.asm
字號:
include debug.mac
.386P
descr struc
limit dw 0
base_l dw 0
base_m db 0
attr_l db 0
attr_2 db 0
base_h db 0
descr ends
trap struc
offs_1 dw 0
sel dw 16
rsrv db 0
attr db 8Fh
offs_h dw 0
trap ends
data segment use16
gdt_0 label word
gdt_null descr <>
gdt_data descr <data_size-1,,,92h>
gdt_code descr <code_size-1,,,98h>
gdt_stack descr <255,0,0,92h,0,0>
gdt_screen descr <4095,8000h,0Bh,92>
gdt_himem descr <511,0,10h,92h,80h>
gdt_tss_0 descr <103,0,0,89h>
gdt_tss_1 descr <103,0,0,89h>
gdt_size=$-gdt_null
idt label word
trap 10 dup (<dummy_exc>)
trap <exc_0Ah>
trap <exc_0Bh>
trap <exc_0Ch>
trap <exc_0Dh>
trap <exc_0Eh>
trap 17 dup (<dummy_exc>)
idt_size=$-idt
pdescr dq 0
real_sp dw 0
real_ss dw 0
mes db 27,'[31;42m Back To Real Mode! ',27,'[0m$';(21)
tblhex db '0123456789ABCDEF'
string db '**** ****_**** ****_**** ****'
len=$-string
number db '???? ????'
home_sel dw home
dw 16
tss_0 db 104 dup (0)
tss_1 db 104 dup (0)
task1_offs dw 0
task1_sel dw 56
data_size=$-gdt_null
data ends
text segment 'code' use16
assume cs:text,ds:data
begin label word
exc_0Ah proc
pop eax
pop eax
mov si,offset string+5
debug
mov ax,0Ah
jmp dword ptr home_sel
exc_0Ah endp
exc_0Bh proc
pop eax
pop eax
mov si,offset string+5
debug
mov ax,0Bh
jmp dword ptr home_sel
exc_0Bh endp
exc_0Ch proc
pop eax
pop eax
mov si,offset string+5
debug
mov ax,0Ch
jmp dword ptr home_sel
exc_0Ch endp
exc_0Dh proc
pop eax
pop eax
mov si,offset string+5
debug
mov ax,0Dh
jmp dword ptr home_sel
exc_0Dh endp
exc_0Eh proc
pop eax
pop eax
mov si,offset string+5
debug
mov ax,0Eh
jmp dword ptr home_sel
exc_0Eh endp
dummy_exc proc
pop eax
pop eax
mov si,offset string+5
debug
mov ax,1111h
jmp dword ptr home_sel
dummy_exc endp
main proc
xor eax,eax
mov ax,data
mov ds,ax
shl eax,4
mov ebp,eax
mov bx,offset gdt_data
mov [bx].base_l,ax
rol eax,16
mov [bx].base_m,al
xor eax,eax
mov ax,cs
shl eax,4
mov bx,offset gdt_code
mov [bx].base_l,ax
rol eax,16
mov [bx].base_m,al
xor eax,eax
mov ax,ss
shl eax,4
mov bx,offset gdt_stack
mov [bx].base_l,ax
rol eax,16
mov [bx].base_m,al
mov eax,ebp
add ax,offset tss_0
mov bx,offset gdt_tss_0
mov [bx].base_l,ax
rol eax,16
mov [bx].base_m,al
mov eax,ebp
add ax,offset tss_1
mov bx,offset gdt_tss_1
mov [bx].base_l,ax
rol eax,16
mov [bx].base_m,al
mov dword ptr pdescr+2,ebp
mov word ptr pdescr,gdt_size-1
lgdt pdescr
mov word ptr tss_1+4Ch,16
mov word ptr tss_1+20h,offset highmem
mov word ptr tss_1+50h,24
mov word ptr tss_1+38h,128
mov word ptr tss_1+54h,8
mov word ptr tss_1+48h,32
cli
mov al,8Fh
out 70h,al
jmp $+2
mov al,0Ah
out 71h,al
mov ax,40h
mov es,ax
mov word ptr es:[67h],offset return
mov word ptr es:[69h],cs
mov word ptr pdescr,idt_size-1
xor eax,eax
mov ax,offset idt
add eax,ebp
mov dword ptr pdescr+2,eax
lidt pdescr
mov al,0D1h
out 64h,al
mov al,0DFh
out 60h,al
mov eax,cr0
or eax,1
mov cr0,eax
db 0EAh
dw offset continue
dw 16
continue: mov ax,8
mov ds,ax
mov ax,24
mov ss,ax
mov ax,32
mov es,ax
mov ax,40
mov gs,ax
mov ax,48
ltr ax
call dword ptr task1_offs
mov word ptr tss_1+20h,offset highmem
call dword ptr task1_offs
mov ax,0FFFFh
home: mov si,offset string
debug
mov si,offset string
mov cx,len
mov ah,74h
mov di,1600
scr: lodsb
stosw
loop scr
mov al,0D1h
out 64h,al
mov al,0DDh
out 60h,al
mov al,0FEh
out 64h,al
hlt
return: mov ax,data
mov ds,ax
mov ax,stk
mov ss,ax
mov sp,256
mov ss,real_ss
sti
mov al,0
out 70h,al
mov ah,09h
mov dx,offset mes
int 21h
mov ax,4c00h
int 21h
main endp
highmem proc
mov ax,40
mov gs,ax
mov eax,0
mov ebx,0
mov ecx,80000h
fill: mov gs:[ebx],eax
push eax
push cx
mov si,offset number+5
debug
shr eax,16
mov si,offset number
debug
mov si,offset number
mov cx,9
mov ah,43h
mov di,1040
scrh: lodsb
stosw
loop scrh
pop cx
pop eax
add ebx,4
inc eax
db 67h
loop fill_l
jmp go
fill_l: jmp fill
go: iret
highmem endp
code_size=$-main
text ends
stk segment stack 'stack'
db 256 dup ('^')
stk ends
end main ?? 快捷鍵說明
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