Assembly sample source codes

 This is a simple litte assembler program that cleans out

This is a simple litte assembler program that cleans out ;* This is a simple litte assembler program that cleans out * ;* the documents folder in the start menu. * ;* This is version 1.2 * ;* There's no command line switches and stuff. * ;* It gives NO messages if everything goes allright. * ;* It check for a environment variable called CLEANDIR and CD:s * ;* down to that dir if the variable is found. If not it uses * ;* the default WINDOWS\RECENT directory and deletes(UNLINKS) * ;* EVERYTHING it finds there, and CD:s back to where it started * ;* from. * ;************************************************************************ ;some euqates for readability kbd equ 16h ;keyboard irq msdos equ 21h ;MSDOS irq reset equ 0dh ;disk reset dfopen equ 0fh ;open disk file dfclose equ 10h ;close disk file searchf equ 11h ;search first searchn equ 12h ;search next seqread equ 14h ;sequential disk read seqwrite equ 15h ; " " write getdisk equ 19h ;get current disk(default) setdta equ 1ah ;set disk transfer area address setdir equ 3bh ;set current directory createf equ 3ch ;create file with handle openf equ 3dh ;open file with handle closef equ 3eh ;close file with handle readf equ 3fh ;read from file with handle writef equ 40h ;write to file with handle unlink equ 41h ;UNLINK(delete file) getdir equ 47h ;get current directory allocmem equ 48h ;allocate memory freemem equ 49h ;free memory changebs equ 4ah ;change block size findfirst equ 4eh ;find first file findnext equ 4fh ;find next file exit equ 4c00h ;msdos exit envir equ 2ch ;offset ENVIRONMENT block [BITS 16] ;NASM STUFF !? [ORG 100h] mov ax,cs ;get code segment mov ds,ax ;use it now mov [comseg],ds mov [extseg],es ;************************ setup and preparing *************************** main: mov ah,setdta ;set our DTA-area mov dx,mydta ;buffer for it int msdos ;call dos mov ah,getdisk ;get default drive int msdos ;call dos add al,41h ;drive in al, make it ASCII mov byte [curdir],al ;fill buffer with name (A:..etc) mov byte [path],al ;and default path mov word [curdir+1],":\" ;copy separator to path mov si,curdir ;pointer path buffer add si,3 ;offset doscall part mov ah,getdir ;get current dir mov dl,0 ;0 = default int msdos ;call dos jnc diskok ;ok mov bx,errt0 ;could not find current dir ?? If You jmp errout ;get an error here You probably have diskok: ;forgot to turn on Your computer. call getenv ;check out if any ENV var cmp dx,-1 ;was it there je findfile ;yeahh mov dx,path ;noo way, use default path mov ah,setdir ;cd down int msdos ;call dos jnc findfile ;all ok mov bx,errt1 ;error jmp errout ;skip ;*************************** the delete file loop *********************** findfile: mov ah,findfirst ;see if the files out there mov cx,0fh ;all files mov dx,files ;our NULL terminated filname(*.*) int msdos ;do the stuff jnc delit ;all ok, must delete first file jmp goback ;error, CD back and skip found: ;found something mov dx,files ;files (*.*) mov ah,findnext ;the function int msdos ;call dos jc goback ;no more files, quit delit: mov ah,unlink ;UNLINK (delete) file mov dx,mydta ;pointer Disk Transfer Area add dx,30 ;offset Filename int msdos ;delete it jnc found ;deleted ok mov bx,errt2 ;could not delete it ???? call write ;let us know mov bx,mydta ;show wich file add bx,30 ;offset filename in DTA call write ;write out filename mov bx,linefeed ;linefeed jmp errout ;and skip goback: mov ah,setdir ;CD back to origin mov dx,curdir ;path to dir int msdos ;do it jnc quit ;all ok, proceed mov bx,errt1 ;error, get text ;*************************** errorexit *********************** errout: call write ;show errormessage quit: xor eax,eax ;clean out that mov ax,exit ;MS-DOS successful exit int msdos ;back to the operating system ;***************** get ENVIRONMENT var if any ***************** getenv: push es ;now check if there's any push ds ;environment variable mov es,[es:+2Ch] ;ES:DI points at environment xor di,di ;which is paragraph-aligned floop: cmp byte [es:di],0 ;if we got 2 zeroes in a row jne goon ;we are at the end of the ENV cmp byte [es:di+1],0 ;variables je eout goon: equal: cmp byte [es:di],'C' ;is it our variable ? jne flop inc byte di cmp byte [es:di],'L' jne flop inc byte di cmp byte [es:di],'E' jne flop inc byte di cmp byte [es:di],'A' jne flop inc byte di cmp byte [es:di],'N' jne flop inc byte di cmp byte [es:di],'D' jne flop inc byte di cmp byte [es:di],'I' jne flop inc byte di cmp byte [es:di],'R' jne flop sign: inc byte di ;dump the R inc byte di ;dump the = mov ax,es ;make DS:DX point to string we found mov ds,ax mov si,di mov bx,si mov dx,bx mov ah,setdir ;func Set Current Directory(CD) int msdos ;do it jnc envok ;all ok, proceed mov dx,0 ;clear flag (use default dir) jmp eout ;return flop: inc byte di ;next byte cmp byte [es:di],0 ;a 0 ? jne flop ;noo inc byte di ;yeahh, dump it jmp floop ;check if two envok: mov dx,-1 eout: pop ds pop es ret ;************************************************************************* ;* Writes out the NULL terminated text supplied in BX. * ;* OR writes out data,BX and size,CX if called at lwrite. * ;************************************************************************* write: pusha mov si,bx ;copy to SI mov cx,0 ;clear count wloop: lodsb ;load AL with SI cmp al,0 ;end of line ? je lwrite ;yeahh inc cx ;no, incrase byte count jmp wloop ;test next byte lwrite: mov dx,bx ;text address in DX mov bx,1 ;filehandle standard output = 1 mov ah,writef ;MS-DOS writefile with handle is 040 int msdos ;write buffer to standard output popa ret ;done ;************************ DATA and BSS stuff *************************** comseg: dw 0 extseg: dw 0 utext: db "XXX",13,10,0 errt0: db "Could not find current directory !",13,10,0 errt1: db "Directory not found.",13,10,0 errt2: db "Could not delete ",0 path: db " :\WINDOWS\RECENT",0 ;default path without DRIVE files: db "*.*",0 linefeed: db 13,10,0 mydta times 128 db 0 ;use 128 bytes as DTA NASM stuff ! curdir times 68 db 0 ;use 64 + 4 bytes for current dir END

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