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Assembly Source File | 1985-12-06 | 15.9 KB | 466 lines

PAGE 64,132 ; ; This program intercepts Int 13H calls and prints ; the drive, side, track, sector, # of sectors, operation, ; and return code. ; ;-------------------------------------------------------------- DISKSTAT segment at 040h ;segment starts at abs. addr. 0400h org 042h ST0 db ? ;Disk status area used after ST1 db ? ; int 13h calls ST2 db ? CYLINDER db ? HEAD db ? RECORD db ? NUMBER db ? DISKSTAT ends ;-------------------------------------------------------------- ; cseg segment org 100h INT13 proc far assume cs:cseg,ds:cseg ; jmp install ;install and make routine resident ; redef13 label word oldint13 dd 0 ;save area for old int13 vector int13loc equ 13h*4h ;vector location for int13h drive_a equ 'A' drive_b equ 'B' drive_c equ 'C' drive_d equ 'D' drive_x equ 'X' save_ip dw 0 ;save area for calling pgm's IP save_cs dw 0 ;save area for calling pgm's CS save_st0 db ? save_st1 db ? save_st2 db ? save_c db ? save_h db ? save_r db ? save_n db ? ; message db 0fh ; code for compressed printing db 'Drv: ' drive db ? db ' Side: ' side1 db ? side2 db ? db ' Tr: ' track1 db ? track2 db ? db ' Sec: ' sector1 db ? sector2 db ? db ' # secs: ' sec_cnt1 db ? sec_cnt2 db ? db ' Op: ' op_1 db ? op_2 db ? db ' Retcd: ' status1 db ? status2 db ? db ' Addr: ' cs_1 db ? cs_2 db ? cs_3 db ? cs_4 db ? db ':' ip_1 db ? ip_2 db ? ip_3 db ? ip_4 db ? db ' ' ;2 spaces db ' ST0: ' sto0_1 db ? sto0_2 db ? db ' ST1: ' sto1_1 db ? sto1_2 db ? db ' ST2: ' sto2_1 db ? sto2_2 db ? db ' ' ;2spaces db ' C: ' c_1 db ? c_2 db ? db ' H: ' h_1 db ? h_2 db ? db ' R: ' r_1 db ? r_2 db ? db ' N: ' n_1 db ? n_2 db ? db 0ah,0dh ;------------------------------ unin_msg db 'INT13 no longer active.......$' inst_msg db 'INT13 is now installed.......$' ; newint13: sti push ax push bp mov bp,sp mov ax,[bp+4] ;Retrieve return IP value mov cs:save_ip,ax ; from stack. mov ax,[bp+6] ;Retrieve return CS value mov cs:save_cs,ax ; from stack. pop bp ;Save anything which will be pop ax ; be changed during pushf ; processing. push di push si push ds push es push bx push cx push dx push ax mov ax,cs mov ds,ax ;---------------DRIVE------------------ cmp dl,00h ;Drive A? (dl=00) jne chk1 ; Note: processing is in place for mov drive,drive_a ; logging disk activity on all jmp drv_exit ; drives, if desired. See below chk1: cmp dl,01h ;Drive B? jne chk2 mov drive,drive_b jmp drv_exit chk2: cmp dl,02h ;Drive C? jne chk3 mov drive,drive_c jmp drv_exit chk3: cmp dl,03h jne chkx mov drive,drive_d jmp drv_exit chkx: mov drive,drive_x drv_exit: ;---------------SIDE (DH) ------------ mov ah,dh ;record side being requested-left digit call leftdig ;convert to ASCII code for printing mov cs:side1,ah ;move code to message area mov ah,dh ;same for right digit call rightdig mov cs:side2,ah ;---------------TRACK NO. (CH)---------- mov ah,ch call leftdig mov cs:track1,ah mov ah,ch call rightdig mov cs:track2,ah ;---------------------------------------- ; ;----------------SECTOR NO. (CL)--------- mov ah,cl call leftdig mov cs:sector1,ah mov ah,cl call rightdig mov cs:sector2,ah ;------------------------------------------ ; ;----------------NO. OF SECTORS (AL)------- ; pop ax ;recall ax push ax ;save it again mov ah,al call leftdig mov cs:sec_cnt1,ah pop ax push ax mov ah,al call rightdig mov cs:sec_cnt2,ah ;-------------------------------------------------- ; ;--------------OPERATION TYPE (AH)----------------- ; 00:reset 01:read status 02:read sectors 03:write sec. 04:verify 05:format ; pop ax ;recall ax push ax ;save it again call leftdig mov cs:op_1,ah pop ax push ax call rightdig mov cs:op_2,ah ;-------------- RETURN ADDRESS CS:IP ------------------- ; mov ax,cs:save_ip call leftdig mov cs:ip_1,ah mov ax,cs:save_ip call rightdig mov cs:ip_2,ah mov ax,cs:save_ip xchg ah,al call leftdig mov cs:ip_3,ah mov ax,cs:save_ip xchg ah,al call rightdig mov cs:ip_4,ah ; mov ax,cs:save_cs call leftdig mov cs:cs_1,ah mov ax,cs:save_cs call rightdig mov cs:cs_2,ah mov ax,cs:save_cs xchg ah,al call leftdig mov cs:cs_3,ah mov ax,cs:save_cs xchg ah,al call rightdig mov cs:cs_4,ah ;-------------------------------- pop ax ;Restore the things which were pop dx ; saved pop cx pop bx pop es pop ds pop si pop di popf ;-------------------- pushf ; Put flags, CS and IP onto stack for return to push cs ; routine below after standard int 13h processing call intcall ; IP will point to next instruction ; ;---------------------------Report status of int 13h call---------- ; pushf push bx push ax ;Save it again call leftdig mov cs:status1,ah pop ax push ax call rightdig mov cs:status2,ah ; ;retrieve the status codes from 0442-0448h ; push ds assume ds:diskstat mov ax,diskstat mov ds,ax mov ah,st0 mov cs:save_st0,ah mov ah,st1 mov cs:save_st1,ah mov ah,st2 mov cs:save_st2,ah mov ah,cylinder mov cs:save_c,ah mov ah,head mov cs:save_h,ah mov ah,record mov cs:save_r,ah mov ah,number mov cs:save_n,ah pop ds assume ds:cseg ;-------------- mov ah,cs:save_st0 call leftdig mov cs:sto0_1,ah mov ah,cs:save_st0 call rightdig mov cs:sto0_2,ah mov ah,cs:save_st1 call leftdig mov cs:sto1_1,ah mov ah,cs:save_st1 call rightdig mov cs:sto1_2,ah mov ah,cs:save_st2 call leftdig mov cs:sto2_1,ah mov ah,cs:save_st2 call rightdig mov cs:sto2_2,ah mov ah,cs:save_c call leftdig mov cs:c_1,ah mov ah,cs:save_c call rightdig mov cs:c_2,ah mov ah,cs:save_h call leftdig mov cs:h_1,ah mov ah,cs:save_h call rightdig mov cs:h_2,ah mov ah,cs:save_r call leftdig mov cs:r_1,ah mov ah,cs:save_r call rightdig mov cs:r_2,ah mov ah,cs:save_n call leftdig mov cs:n_1,ah mov ah,cs:save_n call rightdig mov cs:n_2,ah pop ax pop bx ;------------ PRINT THE MESSAGE -------------------------- cmp dl,00h ;******** REMOVE THESE TWO LINES IF YOU WISH jne goback ;******** ALL DISK ACTIVITY TO BE LOGGED push ax push cx push dx push si mov cx,87h ; Length of message mov si,offset message xor dx,dx prnloop: mov ah,00h mov al,cs:[si] int 17h inc si loop prnloop pop si pop dx pop cx pop ax goback: popf ;------------------------------------------------------- ret 2 ; Go back to calling program. ; Note:"iret" is not used because the flags ; would be popped (and we wish to pass back ; the changed set of flags). The "2" ensures ; that the stack is restored by incrementing ; the stack pointer by two extra bytes. ;----------------------- intcall PROC near ; get set to go to standard int 13h routine pushf push cs:[redef13 + 2] ; "cs" of int 13h routine push cs:[redef13] ; "ip" of int 13h routine iret ; Branch to normal int13h code in ROM intcall endp ;-------------------------- ; Routine to convert high-order digit in AH to an ASCII character ; leftdig PROC and ah,11110000b ; Mask right 4 bits shr ah,1 ; Move high-order digit to low-order pos. shr ah,1 shr ah,1 shr ah,1 cmp ah,0ah ; Check for value 0 through 9 jnb b37 ; If value hex A through F, jump add ah,30h ; Add 30h to make ASCII character jmp b2 b37: add ah,37h ; If hex A-F, add 37h to make ASCII character b2: ret leftdig endp ;----------------------- ; Routine to convert low-order digit in AH to an ASCII character ; rightdig PROC near and ah,00001111b ; mask left 4 bits cmp ah,0ah jnb a37 add ah,30h jmp a1 a37: add ah,37h a1: ret rightdig endp ;----------------------- install: ; First, determine if INT13 has already been installed... push ds ;Save DS mov ax,0000h mov ds,ax ;Need 0 in DS mov di,int13loc ;Move 4C to DI mov bx,[di] ;"IP" of current Int 13 routine mov ax,[di+2] ;"CS" of current Int 13 routine mov ds,ax ;Establish new DS register value mov ch,[bx-1] ;Get byte just before entry point pop ds ;Restore DS value at entry cmp ch,024h ;Look for a "$" je un_inst ;If =, then Int13 is already active ; Proceed with installation mov ax,0 mov es,ax mov di,int13loc ;Save old mov ax,es:[di] ; interrupt 13h mov bx,es:[di+2] ; vector mov si,offset oldint13 ; " mov [si],ax ; " mov [si+2],bx ; " mov ax,0 mov es,ax mov bx,ds cli ;Turn off interrupts mov di,int13loc ;Change int13h .... mov ax,offset newint13 ; vector to... mov es:[di],ax ; point to... mov es:[di+2],bx ; this program. sti ;Turn interrupts back on mov dx,offset inst_msg mov ah,09h ;Print string function int 21h ;Print "install" message ; ;---Check if compressed printing is to be disabled ("8" in parameter string) ; Note: parameter string begins at offset 81h into COM file header, ; and offset 80h contains length of parameter string. ; mov ax,ds ;Make sure ES is the same mov es,ax ; as DS cmp byte ptr es:[80h],00h ;Length of parm. string je no_chng ;If zero, no change mov di,081h ;Start of parm. string mov al,038h ;38h = "8" xor ch,ch ;Zero high-order byte mov cl,es:[80h] ;Length of parm. string cld ;Clear direction flag (forward) repne scasb ;Scan ES:DI 'til match with AL,or CX=0 jne no_chng ;No match means "8" not in parm. strng mov message,00h ;"8" found, so zero out compress char. ;---------------------------------------------------------------------------- no_chng: mov dx,offset install ;Address of end of resident routine int 27h ;Terminate and stay resident ; ;---------------------------------------------------------------------------- ; un_inst: push ds ;Save DS again mov ds,ax ;AX has CS value of current int 13 mov si,bx ;BX has entry point of current int 13 sub bx,0d2h ;Backup D2 bytes to find "old" int 13 mov si,bx ;Establish "source" string start point mov ax,0h mov es,ax ;Zero out ES register for move mov di,int13loc ;Establish "destination" (004Ch) mov cx,04h ;4 bytes to move cld ;Set forward direction for move rep movsb ;Move from DS:SI to ES:DI until CX=0 ; ;At this point, the int 13h vector at 0000:004C has been restored to ; the value it had when INT13 was previously invoked. ; pop ds ;Restore entry DS value mov dx,offset unin_msg ;Location of "un-install" message mov ah,09h ;Prepare for printing int 21h ;Print the message int 20h ;Terminate INT13 endp ;---------------------------------------------------------------------------- cseg ends end INT13