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Assembly Source File | 1987-10-30 | 15.2 KB | 476 lines

;from VOL7N1.ARC, PC Magazine Jan 88? ;---------------------------------------------------------------------- ; CAPTURE is a resident utility which copies an 80x25 screen buffer ; to a file. Activate CAPTURE by pressing ALT-C or any other hot ; key combination defined by the symbols HOTKEY and SHIFT_MASK. ; The filename will be SCREEN.n. The extension begins with .000 and ; is incremented by one each time CAPTURE is activated. ;----------------------------------------------------------------------- ; BIOS_SEG is located in the ROM-BIOS data area ;----------------------------------------------------------------------- BIOS_SEG SEGMENT AT 0040H ORG 0017H KB_FLAG DB ? ;BIOS keyboard shift status ORG 004AH CRT_COLS DB ? ;Current number of screen columns ORG 0050H CURSOR_POSN DW 8 DUP(?) ;Current cursor location ORG 0062H ACTIVE_PAGE DB ? ;Active page for CGA and EGA BIOS_SEG ENDS ;======================================================================= CSEG SEGMENT ASSUME CS:CSEG, DS:CSEG, ES:CSEG ORG 0100H ;Beginning for .COM programs START: jmp Initialize ;Initialization code is at end ;----------------------------------------------------------------------- ; Data needed by this program ;----------------------------------------------------------------------- HOTKEY EQU 2EH ;Scan code for "C" key SHIFT_MASK EQU 00001000B ;Mask for ALT key held down COPYRIGHT DB "CAPTURE 1.0 (c) 1987 Ziff Communications Co" DB 13,10,"Hotkey is ALT-C$",1Ah PROGRAMMER DB "Tom Kihlken" INSTALLED_MSG DB 13,10,"Already Installed$" FILENAME DB "SCREEN.000",0 ;The first filename OLDINT09 DD ? ;Old hardware keyboard interrupt vector OLDINT13 DD ? ;Old BIOS disk IO interrupt vector OLDINT16 DD ? ;Old keyboard input interrupt vector OLDINT21 DD ? ;Old DOS function interrupt vector WRIT_FILE DB 0 ;If=1, need to write to disk ACTIVE DB 0 ;Indicated CAPTURE is in use DOS_STAT DB 0 ;Current DOS function indicator BUSY_FLAGS DB 0 ;Bit masked as follows: ; 1 - DOS function is active ; 2 - BIOS disk IO is active ;----------------------------------------------------------------------- ; CAPTURE reads the screen and stores it in an internal buffer. ;----------------------------------------------------------------------- Capture proc NEAR ASSUME DS:CSEG, ES:BIOS_SEG call Get_Curs_Addr ;Cursor addr for this page PUSH ES:[BX] ;Save the cursor location mov DI,OFFSET BUFFER ;DS:DI points to the buffer xor DX,DX ;Start at row 0, column 0 Read_Loop: cmp DL,CRT_COLS ;Past right edge of screen? jl Not_Past_Edge ;If screen is less than 80 mov AX,0720H ;columns, then pad with a blank jmp SHORT Buff_Char Not_Past_Edge: call Get_Curs_Addr ;Get address of BIOS cursor mov ES:[BX],DX ;Tell BIOS where the cursor is mov BH,ACTIVE_PAGE ;Get active page from BIOS data mov AH,8 ;BIOS function to read character int 10H ;Read the character/attribute Buff_Char: mov [DI],AX ;Put the character in buffer inc DI ;Increment the pointer twice inc DI ;Since we stored a word inc DL ;Do the next char in same row cmp DL,80 ;At the right border yet? jl Read_Loop ;Do 80 characters in this row inc DH ;Move to next row xor DL,DL ;Back to left edge (Column 0) cmp DH,25 ;Done all 25 rows yet? jl Read_Loop ;Loop until whole screen is read call Get_Curs_Addr ;Cursor address for this page POP ES:[BX] ;Recover the cursor position RET ;Then were finished Capture ENDP ;----------------------------------------------------------------------- ; This procedure obtains the address of the cursor position for this page ;----------------------------------------------------------------------- Get_Curs_Addr proc NEAR ASSUME DS:CSEG, ES:BIOS_SEG mov BL,ACTIVE_PAGE ;Get the current page number xor BH,BH ;Convert to a word offset SHL BX,1 ;Times two for a word ADD BX,OFFSET CURSOR_POSN ;Add base cursor address RET Get_Curs_Addr ENDP ;----------------------------------------------------------------------- ; This copies the buffer contents to a file. It should only be called ; when DOS is in a stable and reentrant condition. ;----------------------------------------------------------------------- Write_To_File proc NEAR ASSUME DS:NOTHING, ES:NOTHING mov WRIT_FILE,0 ;Turn off request flag STI ;Get interrupts back on push AX ;Must preserve all registers push BX push CX push DX push BP push DS push ES push CS pop DS ASSUME DS:CSEG ;DS points to out code segment mov AX,3524H ;Get DOS critical error vector call DOS_Function ;Do the DOS function push BX ;Save old INT 24 vector on stack push ES ; Replace the DOS severe error interrupt with out own routine. mov DX,OFFSET NewInt24 mov AX,2524H ;Setup to change INT 24h vector call DOS_Function ;DOS function to change vector ; Try to open the file to determine if it already exists. If it does, ; then just close it and increment the filename. Open_File: mov DX,OFFSET FILENAME ;DS:DX points to filename mov AX,3D00H ;Opin file for read access call DOS_Function ;Do the DOS function jc Open_Error ;If open error, take jump mov BX,AX ;Need the handle in BX mov AH,3EH ;Close this file call DOS_Function ;Do the DOS function call Inc_Filename ;Try the next filename jmp short Open_File Open_Error: cmp AX,2 ;Was it file not found error? jne DOS_Err_Exit ;Exit on any other error ; Now create the file, then write buffer contents and close it. mov DX,OFFSET FILENAME ;DS:DX points to filename mov CX,0020H ;Attribute for new file mov AH,3CH ;Create file for writing call DOS_Function ;Do the DOS function jc Close_File ;On any error, take jump mov BX,AX ;Save handle in BX mov DX,OFFSET BUFFER ;Point to output buffer mov CX,4000 ;Write 4000 bytes mov AH,40H ;DOS write to a device function call DOS_Function ;Do the DOS function Close_File: mov AH,3EH ;DOS function to close the file call DOS_Function ;Do the DOS function call Inc_Filename ;Move to next filename DOS_Err_Exit: pop DS ;Get INT 24H vector from stack ASSUME DS:NOTHING pop DX mov AX,2524H ;Restore critical error vector call DOS_Function ;Do the DOS function pop ES ;Finally restore all registers pop DS pop BP pop DX pop CX pop BX pop AX mov ACTIVE,0 ;CAPTURE is done now RET ;Finished writing to disk Write_To_File ENDP ;----------------------------------------------------------------------- ; This routine does a dos function by calling the old interrupt vector ;----------------------------------------------------------------------- ASSUME DS:NOTHING, ES:NOTHING DOS_Function proc NEAR PUSHF ;These instructions simulate CLI ;an interrupt call CS:OLDINT21 ;Do the DOS function STI RET DOS_Function ENDP ;----------------------------------------------------------------------- ; This procedure increments the extension for the filename. ;----------------------------------------------------------------------- Inc_Filename proc NEAR mov BX,OFFSET FILENAME+9 ;Point to last letter Inc_Next_Char: inc BYTE PTR [BX] ;Increment the extension cmp BYTE PTR [BX],"9" ;Check for carry jle Inc_Return ;If none, were finished mov BYTE PTR [BX],"0" ;Set this digit to zero dec BX ;Backup to next digit cmp BX,OFFSET FILENAME+6 ;Dont increment the dot ; jle Inc_Return ; jmp short Inc_Next_Char ja Inc_Next_Char ;TH Inc_Return: RET Inc_Filename ENDP ;----------------------------------------------------------------------- ; Interrupt 09 (Keyboard) Watch for trigger key. When found, ignore ; it and execute the CAPTURE routine. ;----------------------------------------------------------------------- NewInt09 proc FAR ASSUME DS:NOTHING, ES:NOTHING STI ;Allow other interrupts push AX ;Must save processor state IN AL,60H ;Get the scan code cmp AL,HOTKEY ;Is it the hot key? je Trigger ;If yes, check the mask Int09_Exit: pop AX ;Restore the processor state jmp CS:OLDINT09 ;Continue with ROM routine Trigger: push DS ;Preserve DS register mov AX,BIOS_SEG ;Get BIOS data segment mov DS,AX ;Put it in a segment register ASSUME DS:BIOS_SEG mov AL,KB_FLAG ;Shift flags and AL,0FH ; only cmp AL,SHIFT_MASK ;Is the ALT key down? pop DS ;Restore DS register ASSUME DS:NOTHING jne Int09_Exit ;If ALT not down, ignore it ;Reset the keyboard and 8259 interrutp controller IN AL,61H mov AH,AL or AL,80H ;Reset bit for keyboard OUT 61H,AL ;Reset the keyboard mov AL,AH jmp SHORT $+2 ;A short delay OUT 61H,AL ;Reenable keyboard CLI mov AL,20H OUT 20H,AL ;Reset interrupt controller STI cmp ACTIVE,0 ;Is CAPTURE already active? jnz Short_Ret ;If active, then exit mov ACTIVE,1 ;Its active now push BX ;Must preserve all registers push CX push DX push BP push DI push DS push ES push CS pop DS ;Set DS to CSEG mov AX,BIOS_SEG ;ES points to BIOS data area mov ES,AX ASSUME DS:CSEG, ES:BIOS_SEG ;Assembler directives call Capture ;Read the screen contents mov WRIT_FILE,1 ;Indicate need to flush buffer pop ES ;Restore all registers pop DS pop DI pop BP pop DX pop CX pop BX ASSUME DS:NOTHING, ES:NOTHING TEST BUSY_FLAGS,011B ;Is DOS or BIOS disk busy? jnz Short_Ret ;If yes, then we must wait call Write_To_File ;Otherwise, we'll do it now Short_Ret: pop AX ;Stack must be restored IRET ;Now were all done NewInt09 ENDP ;----------------------------------------------------------------------- ; Interrupt 13H (BIOS diskette I/O) Set the busy flag during diskette I/O ;----------------------------------------------------------------------- NewInt13 proc FAR ASSUME DS:NOTHING, ES:NOTHING PUSHF or CS:BUSY_FLAGS,010B ;Set BIOS busy bit POPF PUSHF ;This simulates an interrupt call CS:OLDINT13 ;Do the BIOS function PUSHF ;Save result flags and BUSY_FLAGS,11111101B ;Clear BIOS busy bit POPF ;Get back result flags STI ;Must return with interrupts on RET 2 ;Return BIOS result flags NewInt13 ENDP ;----------------------------------------------------------------------- ; Interrupt 16H (BIOS keyboard interface) Check to see if the buffer ; needs to be written. ;----------------------------------------------------------------------- NewInt16 proc FAR ASSUME DS:NOTHING, ES:NOTHING cmp CS:WRIT_FILE,1 ;Anything to write to disk? je Check_DOS_Stat ;If yes, see what DOS is doing Bios_Kb: jmp CS:OLDINT16 ;Just do normal KB routine Check_DOS_Stat: cmp CS:DOS_STAT,0AH ;Doing read string? je Begin_Now ;If yes, its safe to begin cmp CS:DOS_STAT,08H ;Doing keybaord input? jne Bios_Kb ;If yes, its safe to begin Begin_Now: call Write_To_File ;Write the buffer to disk or CS:BUSY_FLAGS,001B ;Reset DOS busy bit jmp CS:Bios_Kb ;Continue with BIOS routine NewInt16 ENDP ;----------------------------------------------------------------------- ; Interrupt 21H (DOS functions) Used to keep track of DOS function calls ;----------------------------------------------------------------------- NewInt21 proc FAR ASSUME DS:NOTHING, ES:NOTHING PUSHF ;Save the flags mov CS:DOS_STAT,AH ;Store the function number or CS:BUSY_FLAGS,001B ;Set DOS busy bit or AH,AH ;Doing function zero? jz Jump_To_DOS ;If yes, take the jump cmp AH,4BH ;Doing EXEC function? je Jump_To_DOS ;If yes, take the jump POPF PUSHF call CS:OLDINT21 ;Do the DOS function PUSHF ;Ssve the result flags and CS:BUSY_FLAGS,11111110B ;Clear DOS busy bit cmp CS:WRIT_FILE,1 ;Anything to write to disk? jne No_Write ;If not just return call Write_To_File ;Safe to access disk now No_Write: POPF ;Recover DOS result flags STI ;Must return with interrupts on RET 2 ;Return with DOS result flags Jump_To_DOS: POPF jmp CS:OLDINT21 NewInt21 ENDP ;----------------------------------------------------------------------- ; Interrupt 24H (critical DOS error). This interrupt is only in ; effect during a write screen. It is required to suppress the ; 'Abort, Retry, Ignore' message. All fatal disk errors are ignored. ;----------------------------------------------------------------------- NewInt24 proc FAR ASSUME DS:NOTHING, ES:NOTHING xor AL,AL ;Tells DOS to ignore the error IRET ;Thats all we do here NewInt24 ENDP ;---------------------------------------------------------------------- ; This are is overwritten by the dynamic buffers. ;---------------------------------------------------------------------- PC = $ BUFFER = PC PC = PC+4000 LASTBYTE = PC ;----------------------------------------------------------------------- ; Here is the code used to initialize CAPTURE. It is not keep resident. ; The buffer is located here and overlays the initialization code. ;----------------------------------------------------------------------- ASSUME CS:CSEG, DS:CSEG, ES:NOTHING Initialize proc NEAR mov DX,OFFSET COPYRIGHT mov AH,9 ;DOS display string service int 21H ;Display title message ; Search for a previously installed copy of CAPTURE not WORD PTR START ;Modify to avoid false match xor BX,BX ;Start search at segment zero mov AX,CS ;Compare to this code segment Next_Segment: inc BX ;Look at next segment cmp AX,BX ;Until reaching this code seg mov ES,BX je Not_Installed mov SI,OFFSET START ;Setup to compare strings mov DI,SI mov CX,16 ;16 bytes must match rep CMPSB ;Compare DS:SI to ES:DI or CX,CX ;Did the strings match? jnz Next_Segment ;If no match, try next segment mov DX,OFFSET INSTALLED_MSG ;else, exit with error mov AH,9 int 21H mov AX,4C01H int 21H Not_Installed: mov AX,3509H ;Get keyboard break vector int 21H mov WORD PTR [OLDINT09], BX ;Save segment mov WORD PTR [OLDINT09+2],ES ;Save offset mov DX, OFFSET NewInt09 mov AX, 2509H int 21H ;DOS function to change vector mov AX,3513H ;Get BIOS disk interrupt vector int 21H mov WORD PTR [OLDINT13], BX ;Save the segment mov WORD PTR [OLDINT13+2],ES ;Save the offset mov DX, OFFSET NewInt13 mov AX, 2513H int 21H ;DOS function to change vector mov AX,3516H ;Get keyboard input vector int 21H mov WORD PTR [OLDINT16], BX ;Save the segment mov WORD PTR [OLDINT16+2],ES ;Save the offset mov DX, OFFSET NewInt16 mov AX, 2516H int 21H ;DOS function to change vector mov AX,3521H ;Get DOS function vector int 21H mov WORD PTR [OLDINT21], BX mov WORD PTR [OLDINT21+2],ES mov DX, OFFSET NewInt21 mov AX, 2521H int 21H ;DOS function to change vector ;----------------------------------------------------------------------- ; Deallocate our copy of the enviornment. ; Leave code and space for the buffer resident. ;----------------------------------------------------------------------- mov AX,DS:[002CH] ;Get segment of enviornment mov ES,AX ;Put it into ES mov AH,49H ;Release allocated memory int 21H mov DX,(OFFSET LASTBYTE - OFFSET CSEG + 15)SHR 4 mov AX,3100H int 21H Initialize ENDP CSEG ENDS END START