Software of the Month Club 2000 October

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Assembly Source File | 1999-09-17 | 16KB | 345 lines

; TRAPOUT2.ASM v2.0 by ARK (ark@lhq.com, root@ark.dyn.ml.org) 11-28-97 ; Traps IN and OUT instructions in INT 10h and displays DX and AX/AL values. ; ; In the header "T DX/I AX/L", T is the Type of instruction (I=IN, O=OUT), ; DX/I is the value of DX or the Immediate value if port<256, and AX/L ; is the value of AX or AL depending on if an 8 or 16 bit value is listed. ; AX/L is meaningless for IN's since it is the value if AX/L *before* the ; call to IN. ; ; This is very useful to find information about how your video card works. ; I wrote this to get register dumps for my Trident TVGA9440AGi card so ; that I could use it under Linux. ; ; NOTE: Pipe the output or you won't see anything! ; (ex: TRAP-OUT 4F02 0101 > 640x480.256) ; ; New in v2.0: ; * Traces into INT 10 calls that are called from inside INT 10! ; * Allows AX and BX values to be specified! ; * Command line accepts trailing spaces now. ; x Code to trap INT's also! (T column='N', DX/I=INT ##, AX/L=AX value) ; (Its commented out - but you can recompile with it if you want) ; ; How to assemble with Borland: ; tasm /ml /zd ncr.asm (case sensitive, line number debug info only) ; tlink /x /t ncr.obj (no map, make com file) ; .model tiny ; Tiny memory model, all segments point to the same 64K .286 ; This code will run on a 286... actually, it .code ; Everything is in the code segment(cs) will probably .startup ; Startup run on anything jmp Start ; Go to beginning of progam realINT1 dd 52411A3Eh ; Address of original INT 01h routine offset realINT10 dd 3C1B214Bh ; Memory for [es:bx] of the real INT 10h ; (defaults are '>-ARK!-<' just for looks in the .COM) ; strings no_command_line db 'Use: TRAPOUT2 [AX] [BX]',13,10 db ' Traces all IN/OUT calls inside INT 10h',13,10,36 tracing db 'Tracing INT 10h with AX:',36 bx_msg db ' BX:',36 header db 13,10,'T DX/I AX/L',13,10,36 INT1 proc ; Interrupt Service Routine for Single Step Debugging push ax ; save registers push dx push es push di push bp mov bp,sp ; set bp to the stack push word ptr cs:[bp+12] ; put the real cs pop es ; into es push word ptr cs:[bp+10] ; put the real ip pop di ; into di mov al,byte ptr es:[di] ; set al to the next instruction that will ; be executed after this INT 01 is done. ; This code will trap INT's also... ; cmp al,0CDh ; If al is not CD (INT) keep going ; jne not_int ; If it is, display some stuff... ;; This will skip doing the INT's... ;; add word ptr cs:[bp+10],2 ; Add 2 to the real ip, to skip the INT ; mov dl,4Eh ; Display an N ; mov ah,02h ; The immediate value/DX is the INT ## ; int 21h ; that is called. AX is the value before ; mov dl,20h ; Display a space ; mov ah,02h ; ; int 21h ; Display the immediate value which is ; jmp is_imm ; reallly the interrupt number called. not_int: and al,0F4h ; If al is E4-E7 or EC-EF (all IN/OUT's) cmp al,0E4h ; Then we display our stuff jne not_io ; Otherwise, do nothing ; note: 1 more byte of code after this ; jmp will make it out of range... mov al,byte ptr es:[di] ; Set al to next instruction test al,02h ; If bit 1 is set then we have an OUT jz is_in ; If bit 1 is 0, we have an IN mov dl,4Fh ; Display an O mov ah,02h int 21h jmp dx_or_imd is_in: ; Display an I mov dl,49h mov ah,02h int 21h dx_or_imd: ; Display a space mov dl,20h mov ah,02h int 21h mov al,byte ptr es:[di] ; Set al to next instruction test al,08h ; If bit 3 is set then we are using DX jz is_imm ; If bit 3 is 0, we are using an immediate mov ax,[bp+6] ; restore dx to ax call ShowHex ; Display dx call ShowHex call ShowHex call ShowHex jmp ax_or_al is_imm: mov dl,20h ; Display 2 spaces mov ah,02h int 21h mov dl,20h mov ah,02h int 21h mov ah,byte ptr es:[di+1] ; Set ah to byte after the next instruction call ShowHex ; Display the immediate value call ShowHex ax_or_al: mov dl,2Ch ; Display a comma mov ah,02h int 21h mov al,byte ptr es:[di] ; Set al to next instruction test al,01h ; If bit 0 is set then we are using AX jz is_al ; If bit 0 is 0, we are using AL mov ax,[bp+8] ; Restore ax call ShowHex ; Display ax call ShowHex call ShowHex call ShowHex jmp print_next_line is_al: mov ah,[bp+8] ; Restore al to ah call ShowHex ; Display al call ShowHex print_next_line: mov dl,0Dh ; print a newline mov ah,02h int 21h mov dl,0Ah mov ah,02h int 21h not_io: pop bp ; restore registers pop di pop es pop dx pop ax iret ; end interrupt INT1 endp ; INT 10h that fakes the real INT 10 and sets the trap flag. INT10 proc ; Interrupt Service Routine for Tracing INT 10h push ax ; Save AX pushf ; Put flags on the stack pop ax ; Then into AX or ax,0100h ; Set the trap flag push ax ; Trap Flag calls INT 01h between every instruction popf ; Stuff new flags back into the flags register pop ax ; Restore AX cli ; Fake INT call: clear interrupt flag, skip clearing pushf ; trap flag, push flags, call to location. call cs:[realINT10] ; This call to INT 10h is be trapped for ; IN/OUT/INT Normal INT calls would clear ; the trap flag and then INT 01h would never ; be called. iret ; end interrupt INT10 endp ; function that prints the highest 4 bits of ax as text {0-9,A-F} to stdout ; ax will be shifted left 4 bits on return. ShowHex proc push ax ; save registers push dx shr ax,0Ch ; move the highest 4 bits to the lowest 4 and al,0Fh ; limit to lowest 4 bits or al,30h ; change range to 30h-3Fh {0-9:;<=>?} cmp al,39h ; if it is 30h-39h jbe is_0_thru_9 ; then its already set add al,07h ; otherwise change :;<=>? to A-F is_0_thru_9: mov dl,al mov ah,02h int 21h pop dx ; restore dx pop ax ; restore ax shl ax,4 ; set up ax for next call ret ; return ShowHex endp Start: ; Program begins here mov si,0080h ; CS:0080h is the command line cmp byte ptr [si],10 ; I want it to be at least 10 bytes long jae process_command_line ; if not, abort mov dx,offset no_command_line ; ds is preset mov ah,09h ; Dos function 09h int 21h ; Display no command line string ret ; Exit program process_command_line: inc si ; move si to start of actual string mov ax,[si+1] ; copy first 2 chrs to ax, skipping the space mov bx,[si+3] ; copy 2nd two characters to bx sub al,30h ; subtract 30h so chrs 0-9 have value 0-9 cmp al,09h ; if its 0-9, its ok. jbe al_is_ok ; if its not, its probably A-F or a-f sub al,07h ; so subtract 7 more and al,0Fh ; and limit to 0-F al_is_ok: sub ah,30h ; do the same to ah cmp ah,09h jbe ah_is_ok sub ah,07h and ah,0Fh ah_is_ok: sub bl,30h ; do the same to bl cmp bl,09h jbe bl_is_ok sub bl,07h and bl,0Fh bl_is_ok: sub bh,30h ; do the same to bh cmp bh,09h jbe bh_is_ok sub bh,07h and bh,0Fh bh_is_ok: shl al,04h ; Combine the values so that AL-AH-BL-BH or ah,al ; Goes into --AH- --AL- mov al,bl ; <----AX---> shl al,04h or al,bh mov word ptr [si],ax ; store the value over the string mov ax,[si+6] ; copy 3rd 2 chrs to ax, skip the 2nd space mov bx,[si+8] ; copy 4th two characters to bx sub al,30h ; subtract 30h so chrs 0-9 have value 0-9 cmp al,09h ; if its 0-9, its ok. jbe al_is_ok2 ; if its not, its probably A-F or a-f sub al,07h ; so subtract 7 more and al,0Fh ; and limit to 0-F al_is_ok2: sub ah,30h ; do the same to ah cmp ah,09h jbe ah_is_ok2 sub ah,07h and ah,0Fh ah_is_ok2: sub bl,30h ; do the same to bl cmp bl,09h jbe bl_is_ok2 sub bl,07h and bl,0Fh bl_is_ok2: sub bh,30h ; do the same to bh cmp bh,09h jbe bh_is_ok2 sub bh,07h and bh,0Fh bh_is_ok2: shl al,04h ; Combine the values so that AL-AH-BL-BH or ah,al ; Goes into --AH- --AL- mov al,bl ; <----AX---> shl al,04h or al,bh mov word ptr [si+2],ax ; store the value over the string ; Now [si] contains the real values of AX and BX mov dx,offset tracing ; ds is preset mov ah,09h ; Dos function 09h int 21h ; Display tracing string mov ax,word ptr [si] ; Restore ax call ShowHex ; Display command line call ShowHex ; ax value back to user call ShowHex ; by placing it in ax call ShowHex ; and calling ShowHex mov dx,offset bx_msg ; ds is preset mov ah,09h ; Dos function 09h int 21h ; Display bx message mov ax,word ptr [si+2] ; Restore bx into ax call ShowHex ; Display command line call ShowHex ; bx value back to user call ShowHex ; by placing it in ax call ShowHex ; and calling ShowHex mov dx,offset header ; ds is preset mov ah,09h ; Dos function 09h int 21h ; Display header to output mov ax,3501h ; Dos function 35h, Get vector of INT 01h int 21h ; Store it in es:bx mov word ptr [realINT1],bx ; Store address of original INT 01h mov word ptr [realINT1+2],es ; into realINT1 mov ax,3510h ; Dos function 35h, Get vector of INT 10h int 21h ; Store it in es:bx mov word ptr [realINT10],bx ; Store address of original INT 10h mov word ptr [realINT10+2],es ; into realINT10 so we can fake an INT mov ax,2501h ; Dos function 25h, Store DS:DX to INT 01h mov dx,offset INT1 ; ds is preset, dx is the handler's offset int 21h ; Set new Single Step handler mov ax,2510h ; Dos function 25h, Store DS:DX to INT 10h mov dx,offset INT10 ; ds is preset, dx is the handler's offset int 21h ; Set new Video Interrupt mov ax,word ptr [si] ; We will use the command line ax/bx mov bx,word ptr [si+2] ; values for the fake int call int 10h ; Call my int 10 which fakes the ; real int 10 and traps it. mov ax,2501h ; Dos function 25h, Store DS:DX to INT 01h mov dx,word ptr [realINT1] ; ds/dx are in realINT1 push ds ; Save old ds push word ptr [realINT1+2] ; Put segment on stack pop ds ; Set ds to the segment int 21h ; Reset old Single Step handler pop ds ; Restore old ds mov ax,2510h ; Dos function 25h, Store DS:DX to INT 10h mov dx,word ptr [realINT10] ; ds/dx are in realINT10 push ds ; Save old ds push word ptr [realINT10+2] ; Put segment on stack pop ds ; Set ds to the segment int 21h ; Reset old Video Interrupt pop ds ; Restore old ds mov ax,0003h ; Set ax to 3 int 10h ; Set 80x25 Text mode ret ; End of program end ; End of file