PAGE 64,132 ; ; This program intercepts Int 13H calls and prints ; the drive, side, track, sector, # of sectors, operation, ; and return code. ; 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 ; message 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 0ah,0dh ;------------------------------ 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 ax ;Save it again call leftdig mov cs:status1,ah pop ax push ax call rightdig mov cs:status2,ah pop ax ;------------ 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,52h ; 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: 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 mov dx,offset install ;Address of end of resident routine int 27h ;Terminate and stay resident INT13 endp ;------------------------------ cseg ends end INT13