deppack.nas

Cracker终结者——提供最优秀的软件保护技术

;;
;; aPLib compression library  -  the smaller the better :)
;;
;; NASM 16bit assembler depacker example
;;
;; Copyright (c) 1998-2002 by Joergen Ibsen / Jibz
;; All Rights Reserved
;;
;; -> 16bit by Metalbrain ([e-mail])
;;

                org     256

                cld                     ;Clear direction flag for safety
                mov     ah,4ah          ;Modify memory block size (on start,
                                        ; the .COM program is given all free
                                        ; memory, but this could be less than
                                        ; the needed amount (162K). As a nice
                                        ; side effect, we are freeing unused
                                        ; memory, but who cares under DOS?
                mov     bh,41           ;Number of needed paragraphs
                                        ; (rounded up)
                int     33              ;Resize
                jnc     not_error008    ;Continue if no error
                call    final           ;Exit with message below
                db      "Not enough memory$"
not_error008    mov     si,129          ;Arguments from PSP start here
                pop     cx              ;CX=0 (useful later)
                mov     di,testitnow    ;This will be called quite a few times
                                        ; and later will be used to place
                                        ; variables
                mov     bx,rub+1
space1          mov     dx,si           ;Keep it start infile name in DX
                call    di              ;Parse...
                jz      space1          ;Search for non-space
space2          call    di              ;Keep parsing
                jnz     space2          ;Till a space appears
                mov     [si-1],dh       ;Make infile ASCIIZ
space3          push    si              ;Keep start outfile name in stack
                call    di              ;Still parsing
                jz      space3          ;Now search a non-space again
                mov     [unitoutfile],al;Set unit for temporal outfile
space4          lodsb                   ;Final parse
                cmp     al,":"          ;Is there's a unit in outfile name?
                jnz     nounit          ;No-> skip next
                sub     byte [bx],bh    ;Yes-> temporal outfile includes unit
nounit          cmp     al," "
                ja      space4          ;Space or below means end of filename
                mov     [si-1],dh       ;Make ASCIIZ this one too
                mov     ax,3d00h        ;Function to open infile
                int     33              ;Open infile
                jnc     not_error001    ;Continue if no error
                call    final           ;Exit with message below
                db "Can't open infile$"
not_error001    stosw                   ;Store infile handle at handlein

                pushad
                mov     dx,header
                mov     cl,8            ;Header first part
                mov     bh,3fh
                xchg    ax,bx
                int     33              ;Read 1st part header. No error check
                cmp     dword [header],'AP32'
                jz      not_error009    ;Test for bad infile #3: Header
                call    final
err004          db "Bad infile$"
not_error009    mov     cx,[headersize]
                sub     cx,byte 8
                mov     ah,3fh
                int     33              ;Read 2nd part header
                popad
                mov     dx,[bx]         ;Get outfile name position
                mov     ah,3ch
                int     33              ;Create temporal outfile: "