15号中断0e8号功能问题：探测内存，求助= =
本帖最后由 张国祥 于 2013-2-9 14:58 编辑我给虚拟机分配了64MB内存，使用15号中断探测内存并显示在屏幕上，乍看似乎是对的，但仔细一看，肯定有错，先上图：
第8个ARDS结构的LengthLow（长度）已经达到1000000H，远超64MB，这是什么问题呢？再上代码（补充：此代码首先进入保护模式，接着通过retf进入ring3，再通过调用门回到ring0，再探测内存）：
%include "pm.inc"
org 0100h
jmp start
;enter pm,call data segment,ring0->ring3->ring0,check memory,clean,study page
GDT_DESC: Descriptor 0,0,0
MAIN_DESC: Descriptor 0,mainlen-1,DA_C+DA_32
DATA_DESC: Descriptor 0,datalen-1,DA_DRW+DA_DPL3
STK_DESC: Descriptor 0,TopOfStk+2,DA_DRW
DISP_DESC: Descriptor 0b8000h,0ffffh,DA_DRW+DA_DPL3
CODE3_DESC: Descriptor 0,code3len-1,DA_C+DA_32+DA_DPL3
STK3_DESC: Descriptor 0,TopOfStk3+2,DA_DRW+DA_DPL3
CODE0_DESC: Descriptor 0,code0len-1,DA_C+DA_32
TSS_DESC: Descriptor 0,tsslen-1,DA_386TSS
CALL_GATE: Gate SEL_CODE0,0,0,DA_386CGate+DA_DPL3
gdtlim: dw $-$-1
dd 0
SEL_MAIN EQU MAIN_DESC-$
SEL_DATA EQU DATA_DESC-$+SA_RPL3
SEL_STK EQU STK_DESC-$
SEL_DISP EQU DISP_DESC-$+SA_RPL3
SEL_CODE3 EQU CODE3_DESC-$+SA_RPL3
SEL_STK3 EQU STK3_DESC-$+SA_RPL3
SEL_CODE0 EQU CODE0_DESC-$
SEL_TSS EQU TSS_DESC-$
SEL_CALL_GATE EQU CALL_GATE-$+SA_RPL3
data:
_Msg: db "PM Now!",0
_Titles: db "BaseAddrL BaseAddrH LengthLow LengthHigh Type",0ah,0ah,0
_MemMsg1: db "AVL RAM:",0
_MemMsg2: db "RAM Size:",0
_Cr: db 0ah,0
_ARDSCnt: dd 0
_DisPos: dd 160*2+2*0
_MemAVL: dd 0
_MemTotal: dd 0
_MemCache: times 512 db 0
DataOst Msg
DataOst Titles
DataOst MemMsg1
DataOst MemMsg2
DataOst Cr
DataOst ARDSCnt
DataOst DisPos
DataOst MemAVL
DataOst MemTotal
DataOst MemCache
datalen equ $-$
stk:
times 512 db 0
TopOfStk equ $-$-2
stk3:
times 512 db 0
TopOfStk3 equ $-$-2
ALIGN 32
tss:
dd 0
dd TopOfStk
dd SEL_STK
times 22 dd 0
dw 0
dw $-tss+2
db 0ffh
tsslen equ $-$
ALIGN 32
start:
mov ax,cs
mov ds,ax
mov es,ax
mov ss,ax
mov sp,0100h
mov ebx,0
mov di,_MemCache
mov cx,20
mov edx,534d4150h
chk:
mov eax,0e820h
int 15h
jc chk_err
add di,20
inc dword
cmp ebx,0
je chk_ok
jmp chk
chk_err:
mov dword ,0
chk_ok:
DescInit cs,main,MAIN_DESC
DescInit ds,data,DATA_DESC
DescInit ss,stk,STK_DESC
DescInit cs,code3,CODE3_DESC
DescInit ss,stk3,STK3_DESC
DescInit cs,code0,CODE0_DESC
DescInit ds,tss,TSS_DESC
mov ax,ds
movzx eax,ax
shl eax,4
add eax,GDT_DESC
mov dword ,eax
lgdt
cli
in al,92h
or al,00000010b
out 92h,al
mov eax,cr0
or eax,1
mov cr0,eax
jmp dword SEL_MAIN:0
ALIGN 32
main:
mov ax,SEL_DATA
mov ds,ax
mov ax,SEL_DISP
mov gs,ax
mov ax,SEL_STK
mov ss,ax
mov sp,TopOfStk
mov esi,Msg
mov edi,0
mov ah,0ah
dispm:
mov al,
cmp al,0
je disok
mov ,ax
inc esi
add edi,2
jmp dispm
disok:
mov ax,SEL_TSS
ltr ax
push SEL_STK3
push TopOfStk3
push SEL_CODE3
push 0
retf
mainlen equ $-$
ALIGN 32
code3:
mov ah,0ah
mov al,'3'
mov ,ax
call SEL_CALL_GATE:0
code3len equ $-$
ALIGN 32
code0:
mov ax,Titles
call DispStr
mov ecx,
mov esi,MemCache
d0:
push ecx
mov ecx,5
d1:
mov eax,
call DispInt
mov edi,
mov al,'H'
mov ah,0ch
mov ,ax
add esi,4
add edi,4
mov ,edi
loop d1
mov ax,Cr
call DispStr
sub esi,4
cmp byte ,1
jne noavl
sub esi,8
mov eax,
add ,eax
jmp c0
noavl:
sub esi,8
c0:
mov eax,
add ,eax
add esi,12
pop ecx
loop d0
mov ax,Cr
call DispStr
mov ax,MemMsg1
call DispStr
mov eax,
call DispInt
mov ax,Cr
call DispStr
mov ax,MemMsg2
call DispStr
mov eax,
call DispInt
jmp $
%include "library.inc"
code0len equ $-$
关于代码中引用的文件，通过附件：
问题有些长- -希望大家帮忙= =
在帖子上的代码有问题，貌似不能同时显示两个$$，请大家以附件里的为准 顶起求助，谢谢 {:7_176:}再次顶起。
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