dos下访问ntfs分区，查找指定文件的源代码

哪位高手能帮我看下吗？我写的这个源代码有点儿问题！
程序功能：
　　dos下在ntfs分区中查找一个文件，我主要只用了ntfs中的MFT表格，在表格中找文件记录，当然这样有点儿慢慢！但理论是行得通的．如果我手动把文件记录号设到要查找文件记录附近的话，这个程序就没有问题，但就是我设到用户开始文件记录（开始文件记录号24，我要查找的文件记录号大约为0bc8h号）就要出问题，就是死机！是哪儿的问题呢？哪位高手指点下吗？应该是一个好程序不懂ntfs都可以看哈．
.386
.model small
dseg segment USE16
buffer         db 3fh*512 dup(0)
dap            db 10h,00,01,00,00,00,00,00,00,00,00,00,00,00,00
secperclu      db ?
MftSectorBase  dd ?
SectorsPerFrs  dw ?
namelength     db 5
nextFRS        dd ?
findfilename   dw \'n\',\'t\',\'l\',\'d\',\'r\'
findend        db \"no find file!\",24h
findfile       db \"File Find OK!\",24h
dseg ends

cseg segment USE16                 ;16bit code segment
assume  cs:cseg;ds:dseg;es:dseg;ss:sseg
start proc
mov ax,dseg
mov ds,ax
mov es,ax
mov si,offset dap
mov [si+6],ax             ;read sector segmeng address
mov byte ptr [si+8],3fh   ;set start lba
mov ah,47h
mov dl,80h
int 13h
mov ah,42h
int 13h
mov di,offset buffer
mov ax,0aa55h
cmp [di+1feh],ax          ;is DBR end sign?
jnz exit

mov eax,5346544eh
cmp [di+3],eax            ;is ntfs?
jnz exit

mov ecx,[di+40h]          ;cluster per MFT FRS
neg cl
mov eax,1
shl eax,cl
movzx ebx,word ptr [di+0bh];byte per sector
sub edx,edx                
div ebx                   ; eax = sectors per frs
mov SectorsPerFrs, ax
mov eax, [di+30h]         ;MFT start cluster
movzx ebx, [di+0dh]       ;sector per cluster
mul ebx
add eax,[di+1ch]          ;HiddenSectors                      
mov MftSectorBase, eax    ; SectorBase = mft starting sector

mov nextFRS,24            ;start FRS 24#
loopfrs:
sub eax,eax
mov ax,SectorsPerFrs
mov ebx,nextFRS
mul ebx                   ;FRSstartsector=FRS#*SectorsPerFrs+MftSectorBase
inc nextFRS
add eax,MftSectorBase

mov si,offset dap
mov bx,SectorsPerFrs
mov [si+2],bx            ;set read sector count  
mov [si+8],eax           ;set start lba
mov ah,47h
mov dl,80h
int 13h
mov ah,42h
int 13h

mov di,offset buffer
mov eax,454c4946h
cmp eax,[di]             ;is FRS ?
jnz exit

cmp byte ptr [di+16h],2  ;fies is dir,go nextFRs
jz loopfrs
sub eax,eax
mov ax,offset buffer
call lacattribre
cmp eax,0
jz loopfrs               ;go to next FRS

mov ah,9                 ;print find file
mov dx,offset findfile
int 21h
jmp exit

nofrs:
mov ah,9                ;print find file end
mov dx,offset findend
int 21h

exit:
mov ah,4ch
int 21h

;Find an file attribute in an FRS
lacattribre proc
push di
push si
push ecx
add ax,[eax+14h]         ;FRS FirstAttribute
lacA:
cmp [eax],0ffffffffh     ;is Attribute list end
jz exitlac
mov ecx,30h              ;is filename Attribute?
cmp [eax],ecx                              
jnz lacB

;find file attribute,cmp is find file name?
mov cl,namelength
cmp [eax+58h],cl         ;+18h(size FRS attribe)+40h(length offset in filenameattribute)
jnz lacB
mov si, ax
add si,5ah               ;+18h+42h(filename offset in filename attribute)
mov di,offset findfilename
cld
repe cmpsw               ; zero flag is set if equal
jnz  exitlac             ;no find file name
pop ecx
pop si
pop di
ret                      ;return eax=locate Attribute TypeCode

lacB:
add eax,[eax+4]          ;next Attribute
jmp lacA

exitlac:
sub eax,eax              ;no find file Attribute,set eax=0 exit
pop ecx
pop si
pop di
ret
lacattribre endp
cseg ends
end start

对了这样子就对了
.386
.model small
.stack 0200h
dseg segment USE16
buffer         db 3fh*512 dup(?)
dap            db 10h,00,01,00,00,00,00,00,00,00,00,00,00,00,00
secperclu      db ?
MftSectorBase  dd ?
SectorsPerFrs  dd ?
curreFRS       dd ?
namelength     db 5
findfilename   dw \'n\',\'t\',\'l\',\'d\',\'r\'
findend        db \"No Find File!\",24h
findfile       db \"File Find OK!\",24h
dseg ends

cseg segment USE16        ;16bit code segment
assume  cs:cseg;ds:dseg;es:dseg
start proc
mov ax,dseg
mov ds,ax  ;set segment address
mov es,ax
mov si,offset dap         ;set pointer to Disk Address Packet
mov [si+6],ax             ;set read sector buffer segmeng address
mov byte ptr [si+8],3fh   ;set start lba
mov ah,47h
mov dl,80h
int 13h
mov ah,42h
int 13h
mov di,offset buffer      ;set pointer to read buffer
mov ax,0aa55h
cmp [di+1feh],ax          ;is Boot Record ID?
jnz exit

mov eax,5346544eh
cmp [di+3],eax            ;Version is NTFS?
jnz exit

mov ecx,[di+40h]          ;cluster per MFT FRS
neg cl
mov eax,1
shl eax,cl  ;byte per FRS
movzx ebx,word ptr [di+0bh];byte per sector
xor edx,edx                
div ebx                   ; eax = sectors per frs
mov SectorsPerFrs, eax
mov eax, [di+30h]         ;MFT start cluster
movzx ebx, [di+0dh]       ;sector per cluster
mul ebx
add eax,[di+1ch]          ;HiddenSectors                      
mov MftSectorBase, eax    ;MftSectorBase= MFT starting sector

mov eax,SectorsPerFrs
mov ebx,23                ;ebx=star frs(start user FRS#)
mul ebx                  
add eax,MftSectorBase     ;FRSstartsector=23#FRS*SectorsPerFrs+MftSectorBase
mov curreFRS,eax  ;save FRSstartsector

readfrs:
mov eax,curreFRS
mov ebx,SectorsPerFrs
add eax,ebx               ;eax=Next FRS
mov curreFRS,eax
mov [si+2],bx             ;set read sector count  
mov [si+8],eax            ;set start lba
mov ah,47h
mov dl,80h
int 13h
mov ah,42h
int 13h

mov eax,454c4946h
cmp eax,[di]              ;is FRS single?
jnz nofrs                 ;loop exit

xor eax,eax
mov ax,offset buffer
call lacattribre
cmp eax,0
jz readfrs                ;go to next FRS

mov ah,9                  ;print find file
mov dx,offset findfile
int 21h
jmp exit

nofrs:
mov ah,9                  ;print find file end
mov dx,offset findend
int 21h

exit:
mov ah,4ch
int 21h

;Find an file attribute in an FRS
lacattribre proc
push edi
push esi
push ecx
add ax,[eax+14h]          ;FRS FirstAttribute
lacA:
mov ecx,0ffffffffh
cmp [eax],ecx             ;is Attribute list end?
jz exitlac
mov ecx,30h               ;is filename Attribute?
cmp [eax],ecx                              
jnz lacB

;find file attribute,cmp is find file name?
movzx ecx,namelength
cmp [eax+58h],cl          ;+18h(size FRS attribe)+40h(length offset in filenameattribute)
jnz lacB
mov esi, eax
add si,5ah                ;+18h+42h(filename offset in filename attribute)
mov di,offset findfilename
cld
repe cmpsw                ; zero flag is set if equal
jnz  exitlac              ;no find file name
pop ecx
pop esi
pop edi
ret                       ;return eax=locate Attribute TypeCode

lacB:
add ax,[eax+4]            ;next Attribute add eax,[eax+4] attrib length is 4B
jmp lacA

exitlac:
xor eax,eax               ;no find file Attribute,set eax=0 exit
pop ecx
pop esi
pop edi
ret
lacattribre endp
cseg ends
end start