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Assembly Source File | 1987-10-30 | 21.8 KB | 473 lines

;---------------------------------------------------------------------- ; 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 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 INC_NEXT_CHAR 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