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Assembly Source File | 1988-07-24 | 26.2 KB | 598 lines

; Ed Jordan 201 Smallacombe Drive, Scranton, Pa. 18508 ; program in the public domain ; version 1 - December 1986 ; - improved segment addressing Jan 1987 ; 1.1- correct error for passing dos environment string March 1987 ; 2.0 command line switch to replace entire vector table ; 2.1 support for non-contiguous env blocks ; 2.1a fixed bug - correct for code address in vector table (Mar 88) ; 2.1b fixed bug again - exe and com files have different code segments ; 3.0 enhancements - help , switch for removal of more than one utility ; April 1988 ; 4.0 fixed bug in vector routine - replaces earlier versions May 1988 ; version 4.1 Rewrite of method of detecting memory blocks po equ 39 cr equ 13 lf equ 10 el equ '$' eof equ 1ah esc equ 1bh stdin equ 0 stdout equ 1 stderr equ 2 stdaux equ 3 stdprn equ 4 envsize equ 800h ; max size environment stackseg segment stack para 'stack' db 40 dup('stack') stackseg ends dataseg segment public para 'data' mesg1 db cr,lf,'Deleting ',el mesg2 db ' memory resident programs ...',cr,lf,el mesg2a db ' memory resident program ...',cr,lf,el mesg3 db 'A:\VECTOR.TBL',0 db 20 dup ('PATCH ') db 'END PATCH AREA' mesg4 db 'Replacing entire vector table ...',cr,lf,el mesg5 db 'RESDEL.EXE - version 4.1',cr,lf db 'by Ed Jordan July 1988',cr,lf,el mesg6 db 'RESDEL \n<cr> (n= 1 to 9)',cr,lf db 'RESDEL \R<cr> (delete all)',cr,lf,el mesg7 db cr,lf,el mesg8 db 'Vector(s) ',el mesg9 db '- ',el mesg10 db '- Not Applicable',cr,lf,el mesg11 db 8,' ',8,el error1 db ' not found.',cr,lf,el error2 db 'Insufficient memory.',cr,lf,el error3 db 'Error freeing allocated memory block.',cr,lf,el error4 db 'Please do not try to delete DOS.',cr,lf,el error5 db 'Unrecognized command.',el error6 db '(Warning: Vector not located) ',el error7 db cr,lf,'Warning: SHARE.EXE installed' db cr,lf,'Do you want to proceed? (Y/N) ',el handle dw ? default_tbl dw 0 dos_seg dw ? nxt_env dw ? psp dw ? last_psp dw ? last_env dw ? flag db ? tr_tbl db '0123456789ABCDEF' blocks dw 128 dup (0) dataseg ends codeseg segment public para 'code' assume cs:codeseg,ds:dataseg,es:nothing,ss:stackseg memret proc far mov ax,dataseg mov ds,ax push es pop ax mov psp,ax mov si,16h mov ax,word ptr es:[si] ; parent seg mov dos_seg,ax call chk_share jb ret2 ; exit call read_chain call load_default_tbl jb ret2 call chk_cmd_line jb ret2 lea dx,mesg1 ; delete call print mov dl,cl ; number xor dl,30h mov ah,2 ; print number int 21h cmp dl,31h ; number 1 ? jnz ret6 lea dx,mesg2a jmp short ret7 ret6: lea dx,mesg2 ; programs message ret7: call print jmp short ret4 ret1: mov ax,es mov psp,ax ret4: call find_psp ; look backwards jb ret3 call fix_tbl ; es = last_psp jb ret4 call free_mem ; free last psp jb ret2 call find_env ; find env of psp ret5: loop ret1 ; cx has count jmp short ret2 ret3: lea dx,error4 ; error message call print ret2: mov ax,default_tbl or ax,ax jz ret8 mov es,ax call free_mem ret8: call exit memret endp chk_share proc near mov ah,30h int 21h ; dos version cmp al,3 ; version 3 ? jb cs6 mov ax,1000h ; get installed state int 2fh ; multiplex interrupt cmp al,0ffh ; installed ? jz cs4 cs6: clc jmp cs5 cs4: lea dx,error7 ; error message call print cs3: call get_response cmp al,'Y' jz cs1 cmp al,'N' jz cs2 lea dx,mesg11 ; erase response call print jmp cs3 ; try again cs2: stc ; flag to skip cs1: lea dx,mesg7 ; cr lf call print cs5: ret chk_share endp chk_cmd_line proc near lea dx,mesg5 ; title message call print mov ax,psp mov es,ax mov si,80h ; offset of cmd line mov al,byte ptr es:[si] or al,al jnz ccl4 jmp ccl5 ccl8: lea dx,error5 call print ccl5: lea dx,mesg6 ; help message call print jmp ccl7 ; no command line switch ccl4: mov di,si inc di ; start of cmd line xor cx,cx mov cl,al mov al,'\' ; switch on cmd line repne scasb jcxz ccl5 ; no switch found mov al,byte ptr es:[di] call capital cmp al,'R' jz ccl6 cmp al,'0' jb ccl8 cmp al,'9' jg ccl8 xor al,30h ; make binary digit jz ccl7 xor cx,cx ; in cx mov cl,al jmp ccl1 ccl6: lea dx,mesg4 ; replace whole table call print push es push ds xor ax,ax xor si,si xor di,di mov es,ax mov ax,default_tbl ; copy default table mov ds,ax ; into vector table mov cx,400h cli ; hold interrupts rep movsb ; ds:si to es:di sti ; enable interrupts pop ds pop es mov ax,default_tbl ; free memory for mov es,ax ; the default table call free_mem ccl3: call find_psp ; find previous psp jb ccl7 call free_mem ; free block jb ccl1 call find_env ; free env block jmp ccl3 ccl7: stc ; set carry flag ccl1: ret chk_cmd_line endp capital proc near cmp al,'a' jb cap1 cmp al,'z' jg cap1 xor al,20h cap1: ret capital endp free_mem proc near mov ah,49h ; es= block int 21h jnb fm1 lea dx,error3 ; if carry set call print ; print error message stc fm1: ret free_mem endp fix_tbl proc near db 0cch cld push bp push es push ds push cx lea dx,mesg8 ; vector message call print mov dx,ds ; save ds in dx mov flag,'N' ; no vector default xor ax,ax mov es,ax ; start of vector tbl xor si,si mov cx,400h ; max size of table mov bp,last_psp ; segment of earlier psp mov bx,default_tbl ; set ds to default table mov di,psp ; vector must be between push es ; last_psp and psp pop ds ; ds = es = 0 ft1: cmp si,cx jnb ft2 lodsw lodsw ; segment cmp ax,bp ; compare with last_psp jb ft1 ; must be = or higher cmp ax,di ; psp of current program jnb ft1 ; must be lower call replace call print_num mov ds,dx mov flag,'Y' ; vector located xor ax,ax mov ds,ax jmp ft1 ft2: mov ds,dx cmp flag,'Y' jz ft3 lea dx,error6 ; vector not found message call print clc ft3: pop cx pop ds pop es pop bp ret fix_tbl endp replace proc near push di push si push ds dec si dec si dec si dec si mov di,si mov ds,bx ; table segment movsw movsw ; copy over 2 words pop ds pop si pop di ret replace endp print_num proc near push ax push bx push cx push ds push si mov ds,dx ; data seg dec si ; adj to start of dec si ; vector dec si dec si mov ax,si ; offset of vector shr ax,1 shr ax,1 ; divide by 4 mov ah,al xchg ah,al mov cl,4 shr al,cl mov bx,offset tr_tbl xlat tr_tbl call print_al mov al,ah and al,0fh ; mask off high nibble xlat tr_tbl call print_al mov al,' ' call print_al pop si pop ds pop cx pop bx pop ax ret print_num endp print_al proc near push ax push dx mov dl,al mov ah,2 int 21h pop dx pop ax ret print_al endp find_psp proc near mov si,bp ; end of block chain lea dx,blocks ; beginning of chain std ; reverse fp1: cmp si,dx jb fp2 ; end of loop lodsw mov bx,ax lodsw cmp ax,bx jnz fp1 mov bp,si ; update mov last_psp,ax ; save new psp mov es,ax jmp short fp3 fp2: stc fp3: cld ; foreward ret find_psp endp load_default_tbl proc near lea dx,mesg3 call open_file jnb ldt1 cld ; foreward push es push ds pop es mov di,dx ; path name xor al,al ; look for 0 at end mov cx,128 ; of path repne scasb std ; reverse direction dec di mov byte ptr es:[di],el mov si,di ldt7: lodsb cmp al,'\' jz ldt6 cmp al,':' jnz ldt7 ldt6: inc si inc si cld ; foreward again pop es mov dx,si call print lea dx,error1 ltd4: call print stc jmp ldt2 ldt1: mov handle,ax mov bx,200h call set_memory jnb ldt3 ldt5: lea dx,error2 jmp ltd4 ldt3: mov bx,40h ;paragraphs to request call req_memory jb ldt5 mov default_tbl,ax mov bx,handle mov cx,400h ;size of table push ds mov ds,ax call read_file pop ds jb ldt2 mov bx,handle call close_file ldt2: ret load_default_tbl endp close_file proc near mov ah,3eh int 21h ; bx= handle ret close_file endp read_file proc near xor dx,dx ; ds:dx = buffer mov ah,3fh ; cx= bytes int 21h ; bx= handle ret read_file endp req_memory proc near mov ah,48h ; bx= paragraphs requested int 21h ret req_memory endp set_memory proc near mov ah,4ah ; es= psp int 21h ; bx= paragraphs ret set_memory endp open_file proc near mov ah,3dh ; ds:dx= asciiz xor al,al ; read only int 21h ret open_file endp print proc near push ax mov ah,9 ; dos print message int 21h ; function pop ax ; ds:dx = message ret print endp find_env proc near db 0cch push es push cx mov flag,'N' mov bx,es ; save psp address cld ; foreward push ds pop es lea di,blocks ; start mov dx,di ; at top xor ax,ax ; of the chain mov cx,128 repne scasw dec di dec di dec di dec di mov si,di std ; reverse fe3: cmp si,dx jb fe2 lodsw mov nxt_env,ax lodsw cmp nxt_env,ax jz fe3 cmp ax,bx ; psp match ? jnz fe3 cmp ax,psp ; must not = psp jz fe3 mov flag,'Y' ; found block mov ax,nxt_env mov last_env,ax mov es,ax call free_mem jb fe4 ; exit error jmp fe3 fe2: cmp flag,'N' jz fe5 mov ax,last_env ; equal to last cld ; foreward mov es,ax ; es = env xor di,di xor al,al mov cx,16 * envsize fe8: repne scasb cmp byte ptr es:[di],0 ; two zeros ? jnz fe8 inc di repne scasb ; look for one more 0 repne scasb ; point to end of name dec di mov byte ptr es:[di],el std ; set direction flag mov si,di dec si lea dx,mesg9 ; cr lf message call print push ds push es pop ds fe7: lodsb cmp al,'\' ; point to name minus jz fe6 ; the path and drive cmp al,':' jnz fe7 fe6: inc si inc si mov dx,si call print pop ds lea dx,mesg7 call print jmp short fe4 fe5: lea dx,mesg10 call print fe4: pop cx pop es cld ; clear direction flag ret find_env endp get_response proc near mov ah,1 int 21h call capital ret get_response endp read_chain proc near db 0cch cld push es push ds mov bx,dos_seg lea di,blocks push ds pop es mov ax,bx dec ax ; point to memory ctl blk rc3: xor si,si mov ds,ax ; 1st mem block lodsb ; M or Z cmp al,'Z' ; end of chain jz rc1 lodsw ; get segment address cmp ax,bx ; = dos seg ? jz rc2 or ax,ax ; 0 ? jz rc2 stosw ; save psp address mov ax,ds inc ax stosw ; save block address rc2: lodsw ; get size of block mov dx,ds inc dx add ax,dx jmp rc3 rc1: pop ds pop es ; program dec di dec di mov bp,di ret read_chain endp exit proc near jb e1 xor al,al jmp short e2 e1: mov al,1 ; if carry set exit e2: mov ah,4ch ; with code 1 int 21h exit endp codeseg ends end