Question

我有一个程序可以找到目录中最旧的文件但我无法保存文件的名称，即显示它。我无法理解它可以保存的地方。我可以在dw中保存日期，但是如何保存文件名。这是整个代码：

.model small
.stack 64
.data

path db '*.*',0

 dta  db 256 DUP(?)

er1 db ""

Str db 'Successfully$',0

 fdate   dw 0FFFFH   

 ftime dw 0FFFFH

.code

start:

mov ax,@data
mov ds,ax
xor ax,ax

mov ah,0    
mov al,2     
int 10h 


lea dx,dta       
mov ah,1AH        
int 21h           

mov ah,4EH        
lea dx,path       
mov cx,0          
int 21h           



lea bx,dta        
add bx,18h         
mov dx,[bx]
mov [fdate],dx

lea bx,dta        
add bx,16h         
mov dx,[bx]
mov [ftime],dx



NEXT_LINE:

lea bx,dta       
add bx,18h        
mov dx,[bx]

lea bx,dta       
add bx,16h         
mov cx,[bx]

cmp dx,[fdate] ; if dx < [fdate]
jc CompareDate



cmp dx,[fdate] if dx  = [fdate]
je CompareTime

back:

lea dx,path      
mov ah,4FH        
int 21h           
jc FINISHED      
jmp SHORT NEXT_LINE  

CompareDate:
mov fdate,dx   ; Save date 
mov ftime,cx   ; Save time

jmp back



 CompareTime:
 cmp cx,[ftime]
 jc Swap ;if cx < [ftime] : swap
 jmp back
 Swap:

 mov ftime,cx
 lea bx,dta        
 add bx,16h        
 mov dx,[bx]

 jmp back



FINISHED:

   ;Here I want to display a file name   

int 21h           
mov dx,offset Str
mov ah,09h
int 21h



mov dx,[fdate] ; For a debugger
mov cx,[ftime] ; For a debugger

mov ax,4c00h
int 21h
end start

Answer 1

如果要保存多个值，则必须使用循环。 8086有一个用于复制一堆字节/单词的简短形式：rep movsb（字节）＆amp; rep movsw（字）。我建议你将整个当前最古老的DTA（从FindNext获得）复制到一个＆＃34; shadow＆＃34; DTA。最后，您将获得最旧文件的DTA，并最终可以计算其中的任何信息：

.MODEL small
.STACK 1000h

.DATA

    dta         db 128 DUP(?)
    dta_hold    db 128 DUP(?)
    path        db "*.*",0
    LF          db 13,10,'$'

.CODE

main PROC

    mov ax, @data
    mov ds, ax
    mov es, ax                  ; for movsw

    lea dx, dta                 ; dta: disk transfer area
    mov ah, 1AH                 ; SET DISK TRANSFER AREA ADDRESS
    int 21h                     ; DOS INTERRUPT

    mov ah, 4EH                 ; FIND FIRST MATCHING FILE
    lea dx, path                ; DS:DX -> ASCIZ file specification (may include path and wildcards)
    mov cx, 0                   ; file attribute mask
    int 21h                     ; DOS INTERRUPT

    call store_dta
    call print_filename         ; print the first filename

    FindNext:

    mov ah, 4FH                 ; FIND NEXT MATCHING FILE
    int 21h                     ; DOS INTERRUPT
    jc Finish

    ; compare filedates & filetimes
    lea si, dta_hold            ; DTA of the oldest file
    lea di, dta                 ; DTA of the just found file
    mov ax, [si+18h]            ; filedate
    mov bx, [di+18h]            ; filedate
    cmp ax, bx
    jc FindNext                 ; just found file is newer
    jne Older
                                ; filedates are identical
    mov ax, [si+16h]            ; filetime
    mov bx, [di+16h]            ; filetime
    cmp ax, bx
    jc FindNext

    Older:                      ; just found file is older
    call store_dta              ; copy dta to dta_hold
    jmp FindNext

    Finish:
    call print_filename         ; print the last filename
    mov ax,4c00h
    int 21h

main ENDP

store_dta PROC
    mov cx, (128/2)             ; size of DTA in WORDs (half of BYTEs)
    lea si, dta
    lea di, dta_hold
    rep movsw                   ; copy CX times DS:SI => ES:DI
    ret
store_dta ENDP

print_filename PROC
    lea di, dta_hold + 1Eh
    mov dx, di                  ; start of filename
    _B:                         ; look for NULL (ASCIZ-termination)
    cmp BYTE PTR [di], 0
    je _F
    inc di
    jmp _B
    _F:                         ; replace NULL by '$'
    mov [di], BYTE PTR '$'      ; end-of-string delimiter for INT 21h/09h
    mov ah, 09h                 ; WRITE STRING TO STANDARD OUTPUT
    int 21h                     ; DOS INTERRUPT
    lea dx, LF                  ; new line
    mov ah, 09h                 ; WRITE STRING TO STANDARD OUTPUT
    int 21h                     ; DOS INTERRUPT
    ret
print_filename ENDP

END main

显示目录中最旧文件的名称

1 个答案: