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Assembly Source File | 1988-03-15 | 52.4 KB | 1,776 lines

TITLE ASPRN - Printer Macro Expander PAGE 60,132 ;====================================================================== ; ASPRN - A printer macro expansion utility. A TSR that watches INT 17 ; and looks for an escape sequence of the form [char]x where x={A-Z} and ; expands it to a setup string. Clones itself to include changes in ; the COM file. Different macro characters act like different programs. ; ; Usage: ASPRN [ /U | /S ][ /Mx | /Cnnn ] ; ; 9/12/87 .001 Complete memory management routines. (469) ; .002 Add EXPAND. (674) ; 10/9/87 .003 Clean-up. Start Editor (1030) ; .004 Restructure all code (1026) ; .005 Structure EDITOR proc (1200) ; .006 Add display and pointer routines ; 10/10/87 .007 String edit functions/key reading ; 10/11/87 .008 Extract right/left cursor (1766) ; 11/6/87 .009 Add HOME/END. Fix TTY. (2109) ; 11/7/87 .010 Cleanup. Enhance error messages (2197) ; 11/18/87 .011 Add labels, adjust columns. (2232) ; 11/22/87 .012 Add panic switch, change name (2315) ;---------------------------------------------------------------------- CSEG SEGMENT PARA PUBLIC 'CODE' ASSUME CS:CSEG,DS:NOTHING,ES:NOTHING,SS:NOTHING ;---------------------------------------------------------------------- ; Some common equates. ;---------------------------------------------------------------------- CR EQU 13 ;Common equates LF EQU 10 INS EQU 52H ;Extended ASCII values DEL EQU 53H F7KEY EQU 41H HOME EQU 47H ENDKEY EQU 4FH PGUP EQU 49H PGDN EQU 51H RARROW EQU 4DH LARROW EQU 4BH UARROW EQU 48H DARROW EQU 50H BS EQU 0E08H ;Scan/Ascii code U_SW EQU 1 ;Request to Uninstall S_SW EQU 2 ;Do a Setup M_SW EQU 4 ;Change Escape char ERR_SW EQU 0FFH ;General error ;---------------------------------------------------------------------- ; Start of code. ;---------------------------------------------------------------------- ORG 100H ;Starting offset for COM ENTPT: JMP INITIALIZE ;Skip over resident code ESC_CHAR DB "~" ;Escape char used as part ; of program signature COPYRIGHT DB "ASPRN 1.0 (c) 1988 Ziff Communications Co.",CR,LF DB "PC Magazine ",254," Robert L. Hummel",CR,LF,"$",26 OLD_INT17 DW 0,0 ;Store old vector here ;---------------------------------------------------------------------- ; A Far Pointer is kept to point to strings so they can be found anywhere ; in memory. The length of strings is here as well. These are updated ; when a modified copy is written to disk. ;---------------------------------------------------------------------- STRING_LOC DW OFFSET STRINGS,0 STRING_LEN DW OFFSET STRING_END - OFFSET STRINGS ;======================================================================= ; MACRO EXPANDER - This portion stays resident and is loaded only once. ; Each time a character is output to the printer, check to see if it is ; our escape char. If so, don't send it. The next char will indicate ; which string to send in it's place. If two escape chars are sent in ; a row, print one copy of the escape char. ;---------------------------------------------------------------------- ESC_FLAG DB 0 ;=1 if last was Esc-char PANIC_FLAG DB 0 ;Non-zero in emergencies INT17 PROC FAR ASSUME CS:CSEG,DS:NOTHING,ES:NOTHING,SS:NOTHING CMP CS:PANIC_FLAG,0 ;If panic flag JNE INT17_0 ; do nothing STI ;Allow interrupts OR AH,AH ;If print char function JZ INT17_1 ; check for ESC_CHAR INT17_0: CLI ;Disable interrupts JMP DWORD PTR CS:OLD_INT17 ;Else, continue INT17_1: CMP CS:ESC_FLAG,0 ;Was last char esc? JNE INT17_2 ;Yes, go expand CMP AL,CS:ESC_CHAR ;Is this an esc_char JNE INT17_0 ;No, just print it INC CS:ESC_FLAG ; else, set latch INT17_1A: MOV AH,2 ;Get status instead JMP INT17_0 ; from original interrupt INT17_2: MOV CS:ESC_FLAG,0 ;Clear latch CMP AL,CS:ESC_CHAR ;If second esc_char JE INT17_0 ; output single char OR AL,20H ;Make lower case SUB AL,"a" ;Convert to 0-25 CMP AL,25 ;Must be in range JA INT17_1A ; else ignore CALL EXPAND ;Exand the macro JMP INT17_1A ;Exit with status call INT17 ENDP ;====================================================================== ; Expand the macro for this string combination. Enter with AL = string ; number (must be 0-25). DX = printer number (from original int). ;---------------------------------------------------------------------- EXPAND PROC NEAR ASSUME CS:CSEG,DS:NOTHING,ES:NOTHING,SS:NOTHING PUSH DS ;Saved used registers PUSH SI PUSH CX LDS SI,DWORD PTR STRING_LOC ;Point DS:SI to strings MOV CL,AL ;Each macro occupies two ADD CL,CL ; strings, so double INC CL ; and add one EXP_0: OR CL,CL ;If at selected string JZ EXP_2 ; copy it to printer DEC CL ;Adjust counter EXP_1: LODSB ;Find the string end OR AL,AL ;If not terminating zero JNZ EXP_1 ; continue to read string JMP EXP_0 ;Else find next string EXP_2: LODSB ;Get a char OR AL,AL ;At end of string? JZ EXP_3 ;Yes, exit PUSHF ;No, simulate INT 17h XOR AH,AH ; print the character CALL DWORD PTR CS:OLD_INT17 ; through old int CMP AH,10h ;Check return status JE EXP_2 ; continue if no error EXP_3: POP CX ;Restore used registers POP SI POP DS RET ;And return EXPAND ENDP ;---------------------------------------------------------------------- ; This is the smallest amount of the program that can remain in memory ; and still function. ;---------------------------------------------------------------------- MINIMUM EQU $ ;====================================================================== ; SHRIVEL is really the part of INITIALIZE that makes sure we use as ; little memory as possible by relocating the strings downward. ;---------------------------------------------------------------------- SHRIVEL PROC NEAR ASSUME CS:CSEG, DS:CSEG, ES:NOTHING, SS:NOTHING CLD ;String moves forward MOV SI,OFFSET STRINGS ;Source of strings MOV DI,OFFSET CUTOFF ;Destination MOV CX,STRING_LEN ;Number bytes to move MOV STRING_LOC[2],ES ;New segment of strings MOV STRING_LOC[0],DI ;New offset MOV DX,CX ;Save length of strings ADD DX,DI ; add to program length REP MOVSB ;Move DS:SI to ES:DI ADD DX,15 ;Round to nearest paragraph MOV CL,4 ;Convert to paras SHR DX,CL ; by dividing MOV AX,3100H ;Terminate & stay resident INT 21H ; thru DOS SHRIVEL ENDP ;---------------------------------------------------------------------- ; When terminating for the first time, the SHRIVEL proc must be left ; resident to do the dirty work. Everything after CUTOFF is discarded ; or written over by the strings. ;---------------------------------------------------------------------- CUTOFF EQU $ ;====================================================================== ; The INITIALIZE procedure performs most of the work. It interprets ; the command line switches, checks for previous copies, and does all ; the memory management. Entry is via JMP. ;---------------------------------------------------------------------- NOT_RES$ DB "Not Resident$" CANT_GO$ DB "Cannot Uninstall$" SYNTAX$ DB "Usage: ASPRN [ /U | /S ][ /Mx | /Cnnn ]$" INITIALIZE PROC NEAR ASSUME CS:CSEG, DS:CSEG, ES:CSEG, SS:CSEG ;---------------------------------------------------------------------- ; Set up a local stack at the end of the program. ;---------------------------------------------------------------------- CLI ;Disable interrupts MOV SP,OFFSET STACK_TOP ;SS:SP points to stack STI ;Allow interrupts ;---------------------------------------------------------------------- ; Display the copyright notice. ;---------------------------------------------------------------------- MOV DX,OFFSET COPYRIGHT ;Say who we are MOV AH,9 ;Display string function INT 21H ; Thru DOS ;---------------------------------------------------------------------- ; Release the copy of the environment allocated to this program. The ; segment address of the env block is located at offset 2Ch in the PSP. ;---------------------------------------------------------------------- PUSH ES ;Save register MOV BX,WORD PTR DS:[2CH] ;Get environment segment MOV ES,BX ; in ES ASSUME ES:NOTHING MOV AH,49H ;Free allocated memory INT 21H ; Thru DOS POP ES ;Restore register ASSUME ES:CSEG ;---------------------------------------------------------------------- ; The CMD_LINE procedure looks for switches on the command tail and ; returns them bit-packed in AH. ; ; /S (Setup) will invoke the editor and allow changes to be made to the ; loaded copy and written out to disk. No changes are made to the ; resident copy if one exists. ; /Mx (Macro char) will substitute the char x for the default escape ; char. If the /S parameter is specified, the char will be changed ; in the loaded copy and written back to disk. Otherwise, the char ; is used to determine residency and operation characteristics. ; /Cnnn (escape Char) Same as /E, but allows any char from 001-255 to ; be specified as a decimal number. ; /U (Uninstall) Will flush the resident copy if possible. ; Otherwise, no action. Other switches are ignored. ;---------------------------------------------------------------------- CALL CMD_LINE ;Get switches in AH JNC INIT_1 ;If no carry, no error MOV DX,OFFSET SYNTAX$ ;Show correct syntax INIT_0: MOV AH,9 ;Display string fn INT 21H ; Thru DOS MOV AX,4C01h ;Terminate with error INT 21H ; Thru DOS INIT_1: ;---------------------------------------------------------------------- ; Process the flags. ;---------------------------------------------------------------------- TEST AH,U_SW ;Request to unload? JZ INIT_2 ;No, check next switch CALL UNLOAD ;Unload if possible JC INIT_0 ;Carry set if error MOV AX,4C00H ;Terminate okay INT 21H ; Thru DOS INIT_2: TEST AH,S_SW ;Setup switch on? JZ INIT_3 ;No, check next option JMP SETUP ;Yes, invoke the editor INIT_3: CALL FIND_RES ;Look for resident copy ASSUME ES:NOTHING ; ES may have changed JC LOAD ;No copy found - try load JMP REPLACE ; else, replace INITIALIZE ENDP ;====================================================================== ; This procedure will cause the load copy of the program to become ; resident. The new copy will try to locate the strings as low in ; memory as possible. Hook the interrupt vectors, load the strings, ; and TSR. Entry via JMP. ;---------------------------------------------------------------------- LOAD PROC NEAR ASSUME CS:CSEG, DS:CSEG, ES:CSEG PUSH ES ;Preserve register ASSUME ES:NOTHING ; Changed by next call MOV AX,3517H ;Get BIOS printer INT INT 21H ;Result in ES:BX MOV OLD_INT17[0],BX ;Save old vector MOV OLD_INT17[2],ES ; in local storage POP ES ;Restore register ASSUME ES:CSEG MOV AX,2517H ;Set new interrupt MOV DX,OFFSET INT17 ; to us at DS:DX INT 21H ; Thru DOS ;---------------------------------------------------------------------- ; As loaded, ASPRN owns all memory from its PSP to the end of memory. ; Thus the only memory an allocation call will find will be below us. ; Try to find a low memory block to contain the strings. If success, ; AX contains segment of allocated block. If no room is found, discard ; excess code and relocate strings downward. ;---------------------------------------------------------------------- CALL FIND_LOW ;Look for lower block JNC LOAD_1 ;No Carry if found JMP SHRIVEL ;No room in low mem ;---------------------------------------------------------------------- ; A chunk of memory of suitable size was found below this program at ; segment in AX. Relocate the strings to the new area. DS:SI to AX:DI ; Then TSR,leaving only the macro expander resident in this segment. ;---------------------------------------------------------------------- LOAD_1: CALL MOVE_STRINGS ;Move the strings MOV DX,(OFFSET MINIMUM - OFFSET CSEG + 15) SHR 4 MOV AX,3100H ;Keep process resident INT 21H ; Thru DOS LOAD ENDP ;====================================================================== ; Read the command line. Set flags in AH to indicate which switches ; were included. Note: the /M /C flags are eaten internally and are ; set for ease of later modification. ; 0 = none, 1 = /U, 2 = /S, 4 = /M or /C and AL = x, and FF = error. ; Return carry clear if valid, set if invalid. ; Changes: AX,BX,CX,DX,SI,DI ;---------------------------------------------------------------------- WHITE DB " ,;",9 ;Space,comma,semi,tab WHITE_LEN EQU $ - OFFSET WHITE CMD_LINE PROC NEAR ASSUME CS:CSEG, DS:CSEG, ES:CSEG XOR DH,DH ;Accumulate flags here MOV SI,80H ;Length of cmd line LODSB ;Get byte in AL OR AL,AL ;If parameters JNZ CMD_1 ; process them CMD_0: CLC ;Clear carry = no error MOV AH,DH ;Load flags RET ;Return CMD_1: ;---------------------------------------------------------------------- ; Something is on the line. Let's find out what. ;---------------------------------------------------------------------- MOV BL,AL ;Put char count in BL CMD_2: OR BL,BL ;Any more chars? JZ CMD_0 ;If not, exit LODSB ;Get character in AL DEC BL ;Adjust count MOV DI,OFFSET WHITE ;Compare to these MOV CX,WHITE_LEN ;Number to check REPNE SCASB JE CMD_2 ;Jump if char was white CMP AL,"/" ;Is the char a slash? JE CMD_4 ;Yes, process switch CMD_ERR: MOV AH,ERR_SW ;Signal error STC ;Carry on RET ;Return ;---------------------------------------------------------------------- ; char was slash. Get and process switch in an inelegant fashion. ;---------------------------------------------------------------------- CMD_4: OR BL,BL ;Switch must follow / JZ CMD_ERR ;If not, error LODSB ;Get switch DEC BL ;Reduce count AND AL,NOT 20H ;Make switch upper case CMP AL,"U" ;Request to uninstall JE CMD_5 ; jump if /U CMP AL,"S" ;Setup JE CMD_6 ; jump if /S CMP AL,"M" ;Escape char JE CMD_7 ; jump if /M CMP AL,"C" ;escape Char JE CMD_9 ; jump if /C JMP CMD_ERR ;No more legal options CMD_5: OR DH,U_SW ;Set bit JMP CMD_2 ;Continue scan CMD_6: OR DH,S_SW ;Set bit JMP CMD_2 ;Continue scan CMD_7: OR BL,BL ;Does a char follow? JZ CMD_ERR ;No, syntax error LODSB ;Get new escape char DEC BL ;Reduce parm count CMD_8: MOV ESC_CHAR,AL ;Save in load copy JMP CMD_2 ;Continue scan CMD_9: MOV CX,3 ;Number of digits to read MOV BH,10 ;Constant to multiply by XOR AX,AX ;Set AX=0 MOV DI,AX ; DI=0 CMD_10: OR BL,BL ;Does a char follow? JZ CMD_ERR ;No, syntax error LODSB ;Get a digit in AL DEC BL ;Adjust count SUB AL,"0" ;Make into a number CMP AL,9 ;Make sure it's valid JA CMD_ERR ; else error XCHG DI,AX ;Get total in AX MUL BH ;Multiply by 10 ADD DI,AX ;Add new digit LOOP CMD_10 MOV AX,DI ;Get char in AL JMP CMD_8 ; and save it CMD_LINE ENDP ;====================================================================== ; The UNLOAD proc will look for a copy of ASPRN in memory that has the ; same macro character, and unload if found. Carry clear if successful. ; Set if error and DX points to error msg to display. ;---------------------------------------------------------------------- UNLOAD PROC NEAR ASSUME CS:CSEG, DS:CSEG, ES:CSEG ;---------------------------------------------------------------------- ; Check if already loaded in memory. Don't load multiple copies. ; When search terminates ; ES = BX = segment of first matching copy found in memory. ; CS = DS = AX = segment of current copy as loaded from disk. ; If no previous copy found ; CS = ES = AX = BX ; If previous copy IS found ; (CS = DS = AX) != (ES = BX) ;---------------------------------------------------------------------- CALL FIND_RES ;Look for resident copy ASSUME ES:NOTHING ;May be changed by proc MOV DX,OFFSET NOT_RES$ ;Default error msg JNC UNLOAD_1 ;NC if successful, jump RET ;Return with carry set ;---------------------------------------------------------------------- ; A previous copy was found in memory. Now CS=DS=new copy. ES=BX=old ; copy. Get the segment for the current printer interrupt. If it's ; the same as the seg of the resident copy, then we can deinstall. ;---------------------------------------------------------------------- UNLOAD_1: PUSH BX ;Save resident segment MOV AX,3517H ;Get current BIOS prn INT INT 21H ;Result in ES:BX POP BX ;Discard offset, retrieve ; resident segment MOV DX,OFFSET CANT_GO$ ;Default error message MOV AX,ES ;Int 17 segment in AX (ES) CMP AX,BX ; same as resident segment? JE UNLOAD_2 ;Yes, remove ;---------------------------------------------------------------------- ; Another program has intercepted the printer and we cannot deinstall. ; Turn on the panic switch so that we'll be meerly disabled. ;---------------------------------------------------------------------- UNLOAD_1A: PUSH BX ;Point to resident POP ES ; segment again MOV ES:PANIC_FLAG,0FFH ;Disable expander STC ;Indicate error RET ;Return ;---------------------------------------------------------------------- ; No other TSRs are loaded after us. Perform the removal. ; 1. Restore Int 17h to its previous value. ; 2. Release the MCB that we allocated to hold the strings. ; 3. If code seg different than string block, release MCB for program. ; Note that ES points to the resident segment. ;---------------------------------------------------------------------- UNLOAD_2: LDS DX,DWORD PTR ES:OLD_INT17 ;Get saved vector ASSUME DS:NOTHING ;Changes DS MOV AX,2517H ;Restore it INT 21H ; Thru DOS LES AX,DWORD PTR ES:STRING_LOC ;String segment in ES MOV AH,49H ;Free strings block INT 21H ;Release seg in ES JC UNLOAD_1A ;Panic if error MOV AX,ES ;Move seg to AX CMP AX,BX ;If = program segment JE UNLOAD_3 ; return MOV ES,BX ;Free res code MOV AH,49H ;Free strings INT 21H ; Thru DOS JC UNLOAD_1A ;Panic if error UNLOAD_3: CLC ;Clear carry flag PUSH CS ;Reset DS and ES POP DS ; back to CS PUSH CS POP ES RET UNLOAD ENDP ;====================================================================== ; Search memory to see if a copy of this program has already been ; loaded by looking for copyright notice. ; If found, NC, CS = DS = AX = LOAD COPY, ES = BX = RES COPY ; If not CY, CS = DS = AX = ES = BX = LOAD COPY ;---------------------------------------------------------------------- FIND_RES PROC NEAR ASSUME CS:CSEG, DS:CSEG, ES:NOTHING CLD ;String moves forward NOT WORD PTR [ENTPT] ;Modify to avoid false match MOV BX,600H ;BX = segment to compare MOV AX,CS ;AX = our segment FIND_RES_1: INC BX ;Next paragraph MOV ES,BX ;Set ES to search segment CMP AX,BX ;If not load copy JNE FIND_RES_2 ; test for copyright STC ;Else, flag failure RET FIND_RES_2: MOV SI,OFFSET ENTPT ;String to compare MOV DI,SI ;Offset is same MOV CX,16 ;Compare first 16 bytes REP CMPSB ;CMP DS:SI TO ES:DI OR CX,CX ;All matched? JNZ FIND_RES_1 ;No, continue search CLC ;Set NC = success RET FIND_RES ENDP ;====================================================================== ; The program has been loaded normally, and is already resident. ; Just replace the old strings with the new strings. ; ES = BX = TSR segment ;---------------------------------------------------------------------- BADREPLACE$ DB CR,LF,"ASPRN Failed. Suggest Reboot.",CR,LF,"$" NEWSEGLEN DW 0 REPLACE PROC NEAR ASSUME CS:CSEG, DS:CSEG, ES:NOTHING ;---------------------------------------------------------------------- ; If the old string segment (as recorded in old copy) is the same as ; the resident program segment, then they must be chopped off. ;---------------------------------------------------------------------- MOV AH,50H ;Set active PSP MOV BX,ES ; to TSR INT 21H ;Undocumented DOS MOV AX,ES:STRING_LOC[2] ;Is old string segment CMP AX,BX ; same as old prog seg? JE REPLACE_1 ;Yes, cut them off. ;---------------------------------------------------------------------- ; The strings are in a separate block, so we can just release them. ;---------------------------------------------------------------------- PUSH ES ;Save ES MOV ES,AX ;Segment to release MOV AH,49H ;Free allocated memory INT 21H ; Thru DOS POP ES ;Restore segment JNC REPLACE_2 ;Continue if no erro JMP REPLACE_4 ;---------------------------------------------------------------------- ; Strings are still attaced to the old ASPRN.COM file. We must surgically ; remove them. Shrink the old ES block down to hold just the program. ;---------------------------------------------------------------------- REPLACE_1: MOV BX,(OFFSET MINIMUM - OFFSET CSEG + 15) SHR 4 MOV AH,4AH ;Setblock INT 21H ;Shrink ES JC REPLACE_4 ;---------------------------------------------------------------------- ; Try to locate a block large enough to contain the strings below ; current program (in lower memory). ;---------------------------------------------------------------------- REPLACE_2: CALL FIND_LOW ;Look for memory block JC REPLACE_3 ;Jump if not found ;---------------------------------------------------------------------- ; Room was found. The new segment was returned in AX. ; Relocate the strings. Update the pointers in the resident copy. ;---------------------------------------------------------------------- CALL MOVE_STRINGS ;Copy strings to block MOV AH,50H ;Set active PSP MOV BX,CS ; to US INT 21H ; Thru DOS REPLACE_2A: MOV AX,4C00H ;All done! Terminate. INT 21H ; Thru DOS ;====================================================================== ; There is no room in low memory, so we want to relocate our strings ; to the lowest possible address. We currently own all high memory. ; Shrink this copy's memory down to just enough to hold the program, ; strings, and STACK. ;---------------------------------------------------------------------- REPLACE_3: MOV AH,50H ;Set active PSP MOV BX,CS ; back to us INT 21H ; Undocumented DOS PUSH ES ;Save register MOV AH,4AH ;Change size of blcok MOV BX,(OFFSET LASTBYTE - OFFSET CSEG + 15) SHR 4 MOV NEWSEGLEN,BX ;Save this size PUSH CS ;Set ES to CS POP ES ; i.e., segment to modify INT 21H ; Shrink thru DOS POP ES ;Retrive TSR segment JNC REPLACE_5 REPLACE_4: MOV DX,OFFSET BADREPLACE$ ;Indicate an error MOV AH,9 ;Display string INT 21H ; Thru DOS MOV ES:PANIC_FLAG,0FFH ;Disable expander MOV AX,4CFFH ;Terminate with error INT 21H ; Thru DOS ;---------------------------------------------------------------------- ; Ask for 640K. We'll get an error and BX will contain the largest ; piece of memory available. One of the better DOS functions returns. ; New block will be above us. Allocate all of it. ;---------------------------------------------------------------------- REPLACE_5: MOV AH,48H ;Allocate memory MOV BX,0FFFFH ;Ask for 640K INT 21H ;Available returned in BX CMP BX,(OFFSET LASTBYTE - OFFSET CSEG + 15) SHR 4 JB REPLACE_4 MOV AH,48H ;Allocate BX (all) paras INT 21H ;AX = new segment JC REPLACE_4 ;---------------------------------------------------------------------- ; Duplicate the program at the new address. Copy from ds:si to es:di ;---------------------------------------------------------------------- XOR SI,SI ;SI = 0 MOV DI,SI ;DI = 0 PUSH ES ;Save TSR segment MOV ES,AX ;New block MOV CX,OFFSET LASTBYTE ;Bytes to move CLD REP MOVSB ;Copy to new address POP ES ;---------------------------------------------------------------------- ; Now, hop up to our new home by using a far return. ;---------------------------------------------------------------------- PUSH AX ;Put new CS on stack MOV DX,OFFSET TARGET ;And address of the PUSH DX ; next instruction CLI ;Turn off interrupts DB 0CBH ;Opcode for RETF ;---------------------------------------------------------------------- ; Now we're at AX:TARGET, in the copy of the program. Make it real. ;---------------------------------------------------------------------- TARGET: PUSH CS ;Move stack - lose old POP SS ;Change segment MOV SP,OFFSET STACK_TOP ; and offset STI ;Allow interrrupts MOV BX,AX ;Get the new PSP MOV AH,50H ;Set active PSP INT 21H ; Undocumented DOS ;---------------------------------------------------------------------- ; Release the memory held by the old copy of the program at DS. ;---------------------------------------------------------------------- PUSH ES ;Save register PUSH DS ;Put loaded PSP seg POP ES ; in ES MOV AH,49H ;Free memory INT 21H ; Thru DOS POP ES ;Restore register JC REPLACE_4 ;Panic if error PUSH CS ;Set DS to this new seg POP DS ;---------------------------------------------------------------------- ; Now find the a block for the strings. ;---------------------------------------------------------------------- BREAKPT: MOV AH,50H ;Block must belong to MOV BX,ES ; resident copy INT 21H CALL FIND_LOW ;---------------------------------------------------------------------- ; Copy strings from the new copy at CS:STRINGS newly allocated block. ; Point ES to the RES copy to update the parameters. ;---------------------------------------------------------------------- CALL MOVE_STRINGS ;Transfer strings ;---------------------------------------------------------------------- ; Terminate through bogus PSP. ;---------------------------------------------------------------------- MOV AH,50H ;Set active PSP MOV BX,CS ; to right here INT 21H ;Undocumented DOS again PUSH CS ;Point ES to the POP ES ; current segment MOV AH,4AH ;Setblock MOV BX,NEWSEGLEN ;Same size INT 21H ; Thru DOS JC REPLACE_4 ;Panic if error MOV AX,4C00H ;Terminate thru new PSP INT 21H ; Thru DOS REPLACE ENDP ;====================================================================== ; Look for a piece of memory large enough to hold DS:STRING_LEN bytes. ; This is always taken from the newest program being loaded. ; Changes: AX,BX,CL ;---------------------------------------------------------------------- FIND_LOW PROC NEAR ASSUME CS:CSEG, DS:CSEG, ES:NOTHING MOV AH,48H ;Allocate memory MOV BX,STRING_LEN ;Change length in bytes ADD BX,15 MOV CL,4 SHR BX,CL ; to paras INT 21H ; Thru DOS RET FIND_LOW ENDP ;====================================================================== ; Relocate the strings from DS:STRINGS TO AX:0. Update the pointer ; and length in the resident copy. ;---------------------------------------------------------------------- MOVE_STRINGS PROC NEAR ASSUME CS:CSEG, DS:CSEG, ES:NOTHING PUSH ES ;Save resident segment MOV CX,STRING_LEN ;Bytes to move MOV ES:STRING_LEN,CX ;Update resident copy XOR DI,DI ;Copy to offset 0 MOV ES:STRING_LOC[0],DI ;New offset MOV ES:STRING_LOC[2],AX ;New segment MOV ES,AX ;Destination is ES:DI MOV SI,OFFSET STRINGS ;Source is DS:SI CLD ;String moves forward REP MOVSB ; WHAM! POP ES ;Restore segment RET MOVE_STRINGS ENDP ;====================================================================== ; This proc allows you to edit the strings. On entry CS=DS=ES. ; Total of program code + strings cannot exceed 64K, which is the ; maximum size of a COM file. ;---------------------------------------------------------------------- MEMORY$ DB "Not Enough Memory$" SAVE$ DB CR,LF,"Save changes as ASPRNNEW.COM? (Y/N) $" OVERWRITE$ DB CR,LF,"Overwrite existing file? (Y/N) $" FERROR$ DB CR,LF,"File error. Try Again? (Y/N) $" WERROR$ DB CR,LF,"Write error. Try Again? (Y/N) $" FILENAME DB "ASPRNNEW.COM",0 COM_PTR DW OFFSET STRING_END ;Cannot exceed 64k-200H ROW_END DB 24 ;Defaults for COL_END DB 80 ; common video COL_MAX DB 0 ;Rightmost column VPAGE DB 0 ;Active page ATTR DB 0 ;Selected attribute ;---------------------------------------------------------------------- SETUP PROC NEAR ASSUME CS:CSEG, DS:CSEG, ES:CSEG MOV AH,4AH ;Modify memory block MOV BX,1000H ;Ask for 64K INT 21H ; Thru DOS JNC SETUP_0 ;Jump if no error MOV DX,OFFSET MEMORY$ ;Need more room MOV AH,9 ;Display string INT 21H ; Thru DOS MOV AX,4C02H ;Terminate with error INT 21H ; Thru DOS SETUP_0: CLI ;Disable interrupts MOV SP,0FFFEH ;Move stack to end of seg STI ;Enable interrupts ;---------------------------------------------------------------------- ; Editing requires that we be in a text mode. ; Clear entire screen to desired attribute. ;---------------------------------------------------------------------- CALL VIDEO_SETUP ;Examine video hardware MOV AL,COL_END ;Right edge of screen SUB AL,2 ;(1 based) in one char MOV COL_MAX,AL ;Is rightmost column CALL CLR_BOX ;Draw the window ;---------------------------------------------------------------------- ; Invoke the string editor. Returns when F7 is pressed. ;---------------------------------------------------------------------- CALL EDIT ;String editor MOV CX,COM_PTR ;Get program length SUB CX,OFFSET STRINGS ; minus start of strings MOV STRING_LEN,CX ; is string length ;---------------------------------------------------------------------- ; Ask if changes should be written out to ASPRNNEW.COM. If not, just end. ;---------------------------------------------------------------------- SETUP_1: MOV DX,OFFSET SAVE$ ;Clone the changes? CALL GETRESPONSE ;Yes or No. JC SETUP_2 ;Yes, continue MOV AX,4C03H ;Terminate normally INT 21H ; Thru DOS ;---------------------------------------------------------------------- ; Try to open the file to see if it exists. ;---------------------------------------------------------------------- SETUP_2: MOV AX,3D02H ;Open file for r/w MOV DX,OFFSET FILENAME ; This name INT 21H ; Thru DOS JC SETUP_3 ;Jump if not found MOV BX,AX ;Move handle MOV DX,OFFSET OVERWRITE$ ;Should we overwrite? CALL GETRESPONSE JC SETUP_4 ;Yes SETUP_2A: MOV AH,3EH ;Close file handle INT 21H ; Thru DOS JMP SETUP_1 ;Ask again ;---------------------------------------------------------------------- ; File does not exist. Attempt to open as new. ;---------------------------------------------------------------------- SETUP_3: MOV AH,3CH ;Create file fn XOR CX,CX ; for writing MOV DX,OFFSET FILENAME ; this is name INT 21H ; Thru DOS JNC SETUP_3A ;Opened OK, jump MOV DX,OFFSET FERROR$ ;Error opening file CALL GETRESPONSE ; try again? JC SETUP_3 ;Yes JMP SETUP_1 ;No SETUP_3A: MOV BX,AX ;Put handle in BX ;---------------------------------------------------------------------- ; A valid file handle is in BX. Write away. ;---------------------------------------------------------------------- SETUP_4: MOV AH,40H ; Write to file fn MOV CX,COM_PTR ; Length SUB CX,100H ; Minus PSP length MOV DX,100H ; Pointer to DTA INT 21H ; Thru DOS JC SETUP_5 ;CY signals error CMP AX,CX ;All bytes written? JE SETUP_6 ;Yes ;---------------------------------------------------------------------- ; An error was encountered on the write. ;---------------------------------------------------------------------- SETUP_5: MOV DX,OFFSET WERROR$ CALL GETRESPONSE ;Try again? JC SETUP_4 ;Yes JMP SETUP_2A ;No ;---------------------------------------------------------------------- ; File was written okay. Close and exit. ;---------------------------------------------------------------------- SETUP_6: MOV AH,3EH ;Close file handle in BX INT 21H ; Thru DOS MOV AX,4C00H ;Terminate INT 21H ; Thru DOS SETUP ENDP ;====================================================================== ; Accept only a Y or N answer. Return CY if YES, NC if NO. DX contains ; offset of prompt to print. ;---------------------------------------------------------------------- GETRESPONSE PROC NEAR ASSUME CS:CSEG, DS:CSEG, ES:CSEG MOV AH,9 ;Display string fn INT 21H ; Thru DOS GETR_0: CALL GETKEY ;Get a keystroke AND AL,NOT 20H ;Capitalize CMP AL,"N" ;If NO, JNE GETR_1 ;If equal, CY is off RET ; just end GETR_1: CMP AL,"Y" ;If not YES, JNE GETR_0 ; try again STC ;Carry on RET GETRESPONSE ENDP ;====================================================================== ; Determine all the paramters and info we need to handle the display. ; Return with carry set if incomaptible mode. ;---------------------------------------------------------------------- COLOR_ATTR EQU 1FH ;Brite white/blue BW_ATTR EQU 07H ;Reverse video VIDEO_SETUP PROC NEAR ASSUME CS:CSEG, DS:CSEG, ES:CSEG MOV AH,0FH ;Get video mode INT 10H ; Thru BIOS MOV ATTR,COLOR_ATTR ;Assume color screen CMP AL,3 ;CGA video modes JBE VID_3 ; are okay CMP AL,7 ;MDA text mode JE VID_2 ; is okay, too. STC ;Else, an error RET ;Return VID_2: MOV ATTR,BW_ATTR ;Force B/W VID_3: MOV COL_END,AH ;Save cols MOV VPAGE,BH ;Save current page ;---------------------------------------------------------------------- ; Determine if an EGA/VGA adapter is installed, and find row count. ;---------------------------------------------------------------------- MOV AH,12H ;EGA alternate select MOV BL,10H ;Return EGA info INT 10H ;Thru BIOS CMP BL,10H ;If BL unchanged MOV DL,24 ;Set default rows JE VID_4 ; there's no EGA/VGA PUSH ES ;Changed by call MOV AX,1130H ;EGA info call MOV BH,0 ;Dummy argument INT 10H ; thru BIOS POP ES VID_4: MOV ROW_END,DL ;Save rows CLC RET VIDEO_SETUP ENDP ;====================================================================== ; Position the cursor to the stored values. ; Changes BX ;---------------------------------------------------------------------- CUR_SET PROC NEAR ASSUME CS:CSEG, DS:CSEG, ES:NOTHING PUSH AX ;Save used register MOV AH,2 ;Position cursor fn MOV BH,VPAGE ; current page MOV DX,CURSOR_POS ; new cursor position INT 10H ; Thru BIOS POP AX ;Restore register RET CUR_SET ENDP ;====================================================================== ; The EDIT procedure handles all the editing. It keeps track of the ; current macro strings and displays them on the screen as they change. ;---------------------------------------------------------------------- ; The PTR offset points to the character that appears at the left side ; of the window PTR_ARRAY LABEL WORD ;Indicates the starting NAM_PTR DW 0 ; offset of the current STR_PTR DW 0 ; macro name and string ACTIVE DW 0 ;Index for array ; The screen column for positioning the cursor. Common data. CURSOR_POS LABEL WORD CURSOR_COL DB 6 ;Current cursor CURSOR_ROW DB 0 ; position MACRO_PTR DB 0 ;Pointer to string set INS_STATE DB 0 ;0=INS FF=TYPEOVER ;====================================================================== EDIT PROC NEAR ASSUME CS:CSEG, DS:CSEG, ES:CSEG MOV MACRO_PTR,0 ;Choose first string ;---------------------------------------------------------------------- ; Display the Macro letter for these strings. ;---------------------------------------------------------------------- EDIT_1: MOV CURSOR_POS,0106H ;Move to row 1 col 2 CALL CUR_SET MOV AH,0AH ;Write character MOV AL,ESC_CHAR ; char to write MOV CX,1 ; repeat count INT 10H ; Thru BIOS INC CURSOR_COL ;Move to next column CALL CUR_SET MOV AH,0AH ;Write character MOV AL,MACRO_PTR ; number of macro ADD AL,"A" ; convert to letter MOV CX,1 ; repeat count INT 10H ; Thru BIOS ;---------------------------------------------------------------------- ; Initialize the pointers to point to the first macro set. ;---------------------------------------------------------------------- CALL LOAD_POINTERS ;---------------------------------------------------------------------- ; Display the selected strings on the screen as read from memory. ;---------------------------------------------------------------------- MOV BX,0 ;Index for Name CALL MAKE_ACTIVE ;Put cursor in NAME CALL DISPLAY ;Show the string MOV BX,2 ;Index for Macro EDIT_2: CALL MAKE_ACTIVE ;Put cursor in MACRO CALL DISPLAY ;Show the string ;---------------------------------------------------------------------- ; Get a key from the keyboard and act on it. ;---------------------------------------------------------------------- KEY_0: CALL GETKEY ;Read a key into AX OR AL,AL ;If 0, is extended JZ KEY_2 ; which means command CMP AX,BS ;If not actual BS key JNE KEY_1 ;Process as char OR AH,AH ;If high byte is zero JZ KEY_1 ;Process as char ;---------------------------------------------------------------------- ; The backspace key is the only key that requires special handling. ; Treat BS as a CURSOR-LEFT/DELETE combination. ;---------------------------------------------------------------------- CALL CURSOR_LEFT JC KEY_0 KEY_0A: CALL STRING_DEL ;Delete char at cursor JC KEY_0 CALL DISPLAY CMP ACTIVE,0 ;If deleted from first JNE KEY_0 DEC PTR_ARRAY[2] ;Back up second JMP KEY_0 ;---------------------------------------------------------------------- ; Put the character on the screen and in the string. ;---------------------------------------------------------------------- KEY_1: CMP INS_STATE,0 ;If insert JE KEY_1A ; jump ;---------------------------------------------------------------------- ; If at end of string, typeover works just like insert. ;---------------------------------------------------------------------- CALL LOCATE_SI ;If current char CMP BYTE PTR [SI],0 ; isn't a zero byte JNZ KEY_1B ; just overwrite KEY_1A: CALL STRING_INS ;Create hole at cursor CMP ACTIVE,0 ;If inserting first JNE KEY_1B INC PTR_ARRAY[2] ;Advance second KEY_1B: CALL PUTCHAR ;Put AL at cursor CALL DISPLAY ;Show changes ;Fall through ;---------------------------------------------------------------------- ; -> Move the cursor to the right one space. ;---------------------------------------------------------------------- KEY_1C: CALL CURSOR_RIGHT ;Move cursor along JMP KEY_0 ;---------------------------------------------------------------------- ; Key is an extended key. Must be an instruction. ;---------------------------------------------------------------------- KEY_2: CMP AH,F7KEY ;F7 is the exit key JNE KEY_3 MOV CURSOR_COL,0 ;Reposition cursor MOV CURSOR_ROW,NROW ; for message CALL CUR_SET RET ; and the only way out ;---------------------------------------------------------------------- ; All remaining key dispatch done from here. ;---------------------------------------------------------------------- KEY_3: MOV BL,MACRO_PTR ;Number of set CMP AH,DEL ;Kill char at cursor JE KEY_0A CMP AH,PGUP ;Check for PgUp JE KEY_3A ; else check next CMP AH,PGDN ;Move to next macro JE KEY_5 MOV BX,ACTIVE CMP AH,RARROW ;Move right 1 char JE KEY_1C CMP AH,LARROW ;Move left JE KEY_9 CMP AH,UARROW ;Move up JE KEY_12 CMP AH,DARROW ;Move down JE KEY_14 CMP AH,INS ;Use Insert mode JE KEY_15 CMP AH,ENDKEY ;Move to end of string JE KEY_16 CMP AH,HOME ;Move to start of string JE KEY_17 JMP KEY_0 ;Didn't recongnize it ;---------------------------------------------------------------------- ; PgUp key: Move to the previous macro. ;---------------------------------------------------------------------- KEY_3A: DEC BL ;Back up CMP BL,0 ;If below 0 JGE KEY_4 MOV BL,25 ; reset to end KEY_4: MOV MACRO_PTR,BL ;Update pointer JMP EDIT_1 ;Start over ;---------------------------------------------------------------------- ; PgDn key: Move to the next macro. ;---------------------------------------------------------------------- KEY_5: INC BL ;Go forward CMP BL,25 ;If past end JBE KEY_4 XOR BL,BL ;Reset JMP KEY_4 ;---------------------------------------------------------------------- ; <- Move the cursor to the left one space. ;---------------------------------------------------------------------- KEY_9: CALL CURSOR_LEFT ;Move cursor left KEY_10: JMP KEY_0 ;Failed, ignore it ;---------------------------------------------------------------------- ; ^ Move to the NAME field. ;---------------------------------------------------------------------- KEY_12: CMP BX,0 ;If already active JE KEY_10 ; ignore MOV BX,0 ;Else, switch JMP EDIT_2 ;---------------------------------------------------------------------- ; v Move to the STRING field. ;---------------------------------------------------------------------- KEY_14: CMP BX,2 ;If already active JE KEY_10 ; ignore MOV BX,2 ;else, switch JMP EDIT_2 ;---------------------------------------------------------------------- ; Toggle the insert/typeover state. ;---------------------------------------------------------------------- KEY_15: NOT INS_STATE ;Toggle the flag JMP KEY_0 ;---------------------------------------------------------------------- ; Move to end of string. ;---------------------------------------------------------------------- KEY_16: CALL CURSOR_RIGHT ;Move to the right JNC KEY_16 ; as long as successful JMP KEY_0 ;---------------------------------------------------------------------- ; Move to start of string. ;---------------------------------------------------------------------- KEY_17: CALL CURSOR_LEFT ;Move to the left JNC KEY_17 ; as long as successful JMP KEY_0 EDIT ENDP ;====================================================================== ; Clear a window (box) for our information on the screen. ; Add a border for a nice touch. ;---------------------------------------------------------------------- TITLE$ DB 0B5H,"ASPRN 1.0",0C6H,0 TITLE_LEN EQU $-TITLE$ HELP$ DB "STRING: ",27,32,26," INS DEL ",24,32,25 DB " MACRO: PgUp PgDn F7 = Save",0 NAME$ DB "NAME :",0 MACRO$ DB "MACRO:",0 BOX_CHARS DB 0C9H,0CDH,0BBH,0BAH,020H,0BAH DB 199,196,182,0C8H,0CDH,0BCH NROW EQU 9 CLR_BOX PROC NEAR ASSUME CS:CSEG, DS:CSEG, ES:NOTHING MOV AX,0700H ;Scroll window fn MOV BH,ATTR ; clear to this color XOR CX,CX ;Start row,col MOV DH,ROW_END ;End row,col MOV DL,COL_END DEC DL INT 10H ;Thru BIOS MOV BH,VPAGE ;Get active page MOV SI,OFFSET BOX_CHARS ;Draw the edit window MOV DX,CX ;Cursor from last call MOV CX,NROW ;Number of rows to draw CB_1: PUSH CX ;Save counter MOV DL,0 MOV AH,2 ;Position cursor INT 10H ;Thru BIOS LODSB ;Get leftmost char MOV AH,0EH ;Write char TTY INT 10H ;Thru BIOS LODSB ;Get middle char MOV AH,0AH ;Write repeated char MOV CL,COL_END ;Width of box XOR CH,CH SUB CX,2 ; minus 2 sides INT 10H ;Thru BIOS MOV AH,2 ;Position cursor MOV DL,0 ADD DL,COL_END DEC DL ;Col = righthand edge INT 10H ;Thru BIOS LODSB ;Get rightmost char MOV AH,0AH ;Write char MOV CX,1 INT 10H ;Thru BIOS INC DH ;Next row POP CX ;Restore counter CMP CL,NROW ;Examine row we wrote JE CB_2 ;If first row CMP CL,2 ;or next to last JNE CB_1A ;Don't adjust count ADD SI,3 CB_1A: TEST CL,1 ;If row is even JZ CB_2 ;Don't adjust count SUB SI,6 CB_2: LOOP CB_1 MOV CURSOR_ROW,0 ;Top row MOV AL,COL_MAX ;Rightmost column SUB AL,TITLE_LEN+5 ;Backup MOV CURSOR_COL,AL ; to here MOV SI,OFFSET TITLE$ ;Program name CALL CB_3 MOV CURSOR_POS,0701H MOV SI,OFFSET HELP$ ;Instructions CALL CB_3 MOV CURSOR_POS,0301H MOV SI,OFFSET NAME$ ;And titles CALL CB_3 MOV CURSOR_POS,0501H MOV SI,OFFSET MACRO$ CB_3: CALL CUR_SET ;Position cursor CB_3A: MOV BH,VPAGE ;Use active page LODSB ;Get a char OR AL,AL ;If zero JZ CB_4 ; quit MOV AH,0EH ;Else, write TTY INT 10H ; Thru BIOS JMP CB_3A ;Continue CB_4: RET CLR_BOX ENDP ;====================================================================== ; Write the character in AL to the string as SI. ; Changes: SI ; Calls: LOCATE_SI ;---------------------------------------------------------------------- PUTCHAR PROC NEAR CALL LOCATE_SI ;Point to cursor location MOV [SI],AL ; and pop in char RET PUTCHAR ENDP ;====================================================================== ; Point SI to the same char in the string that is currently above the ; cursor on the screen. ; Changes: BX,SI,CX ;---------------------------------------------------------------------- LOCATE_SI PROC NEAR MOV BX,ACTIVE ;Get active index MOV SI,PTR_ARRAY[BX] ;Read string from this pt XOR CH,CH ;Adjust the start of MOV CL,CURSOR_COL ;the string to point SUB CL,7 ;to the char at the ADD SI,CX ;cursor RET LOCATE_SI ENDP ;====================================================================== ; Create a hole in the string by moving everything to the right. ; Changes: SI,DI,CX ; Calls: LOCATE_SI ;---------------------------------------------------------------------- STRING_INS PROC NEAR CALL LOCATE_SI ;SI = current char MOV CX,COM_PTR ;End of strings offset MOV DI,CX ;Is also target for move SUB CX,SI ;Bytes to move MOV SI,DI ;Copy to source register DEC SI ;Copy from previous byte STD ;Move backwards REP MOVSB ; whole string INC COM_PTR ;File is longer RET STRING_INS ENDP ;====================================================================== ; Delete the char at the cursor. Close up the string. ; Changes: CX,SI,DI ; Calls: LOCATE_SI ;---------------------------------------------------------------------- STRING_DEL PROC NEAR CALL LOCATE_SI ;Point to current char CMP BYTE PTR [SI],0 ;Can't backup too far JNZ SD_1 STC ;Error RET SD_1: MOV CX,COM_PTR ;End of strings offset SUB CX,SI ;Bytes to move DEC CX ;Is one less MOV DI,SI INC SI ;Copy from previous byte CLD ;Move backwards REP MOVSB DEC COM_PTR ;File gets shorter CLC RET STRING_DEL ENDP ;====================================================================== ; Move the cursor left/right 1 char. Return NC if success. CY if fail. ; Changes: SI,CX ; Calls: LOCATE_SI, CUR_SET, DISPLAY ;---------------------------------------------------------------------- CURSOR_RIGHT PROC NEAR CALL LOCATE_SI CMP BYTE PTR [SI],0 ;Are we on last char JNE CR_0 ;of string? jmp if yes CR_A: STC ;Signal failure RET CR_0: MOV CL,CURSOR_COL CMP CL,COL_MAX ;Is cursor at screen edge JE CR_2 ;yes, jump INC CL ;Move to next col CR_1: MOV CURSOR_COL,CL ;Save (getkey updates) CALL CUR_SET CLC ;Signal success RET CR_2: INC PTR_ARRAY[BX] ;Move the start PUSH CURSOR_POS ;Save current cursor MOV CURSOR_COL,7 ;Redisplay from left side CALL CUR_SET ;Set cursor CALL DISPLAY ;Draw string POP CURSOR_POS ;Reset old cursor CALL CUR_SET CLC RET ;---------------------------------------------------------------------- CURSOR_LEFT PROC NEAR MOV CL,CURSOR_COL ;Is cursor CMP CL,7 ; at 1st column? JE CL_1 ;Yes, jump DEC CL ;Back up cursor JMP CR_1 CL_1: MOV SI,PTR_ARRAY[BX] ;Start of window DEC SI ;Back one char CMP BYTE PTR [SI],0 ;Past start of string? JE CR_A ;Yes, jump MOV PTR_ARRAY[BX],SI CALL DISPLAY CLC RET CURSOR_LEFT ENDP CURSOR_RIGHT ENDP ;====================================================================== ; On entry BX contains 0 = Name or 2 = String. This proc makes the ; selected string "active." The cursor position is determined from ; the pointer positions and are retained when jumping up and down. ; Changes: DH ;---------------------------------------------------------------------- MAKE_ACTIVE PROC NEAR MOV ACTIVE,BX ;Change active index MOV CURSOR_COL,7 ;Leftmost column MOV DH,3 ;Row for name OR BX,BX ; if bx=0 JZ MA_1 MOV DH,5 ;Else row for string MA_1: MOV CURSOR_ROW,DH ;Save coords RET MAKE_ACTIVE ENDP ;====================================================================== ; Load the pointers for a new macro set. ; Changes: BL ; Calls: GET_POINTER ;---------------------------------------------------------------------- LOAD_POINTERS PROC NEAR ASSUME CS:CSEG, DS:CSEG, ES:CSEG MOV BL,MACRO_PTR ;String to look for SHL BL,1 ; they come in pairs CALL GET_POINTER ;Load pointer MOV NAM_PTR,SI ;Save offset INC BL ;Next string CALL GET_POINTER ;Load pointer MOV STR_PTR,SI ;Save offset RET LOAD_POINTERS ENDP ;====================================================================== ; Find the BLth string in the list. 0-based. Returns SI pointing ; to the start of the string. ; Changes: AX,BH,SI ;---------------------------------------------------------------------- GET_POINTER PROC NEAR ASSUME CS:CSEG, DS:CSEG, ES:CSEG MOV SI,OFFSET STRINGS ;Start scan here XOR BH,BH ;String counter GP_0: CMP BH,BL ;Pointing to right string? JNE GP_1 ;No, keep scanning RET GP_1: LODSB ;Read char OR AL,AL ;Is it 0? JNZ GP_1 INC BH JMP GP_0 GET_POINTER ENDP ;====================================================================== ; This procedure will write the active string to the screen from the ; current cursor position forward. It is called only when a char is ; typed or the window is pushed. ; Changes: AX,BX,CX,SI ; Calls: CUR_SET, LOCATE_SI ;---------------------------------------------------------------------- DISPLAY PROC NEAR ASSUME CS:CSEG, DS:CSEG, ES:CSEG CLD ;String moves forward CALL CUR_SET ;Position the cursor CALL LOCATE_SI ;Point SI to string MOV CH,CURSOR_COL MOV CL,COL_MAX ;Rightmost column DISPLAY_0: LODSB ;Get character OR AL,AL ;Is it end of string? JNZ DISPLAY_1 ;No, jump DEC SI ;Yes, back up MOV AL,20H ;Print a space DISPLAY_1: CALL CUR_SET ;Position the cursor PUSH CX ;Save register MOV AH,0AH ;Write Char MOV BH,VPAGE ;Active page MOV CX,1 INT 10H ;Thru BIOS POP CX ;Restore register INC CURSOR_COL ;Change position CMP CL,CURSOR_COL ;Is col <= end? JAE DISPLAY_0 ;Yes, continue ; Past the end of the window - done with display. MOV CURSOR_COL,CH ;Return to old spot CALL CUR_SET ; do it RET DISPLAY ENDP ;====================================================================== ; Get a character from the keyboard. Generate Idle interrupt for ; compatibility with other TSRs. ; Changes: AX ;---------------------------------------------------------------------- GETKEY PROC NEAR ASSUME CS:CSEG, DS:CSEG, ES:CSEG GETKEY_1: INT 28H ;Generate Dos Idle MOV AH,1 ;Request KBD status INT 16H ; Thru BIOS JZ GETKEY_1 ;None ready XOR AH,AH ;Fetch the key INT 16H ; Thru BIOS RET GETKEY ENDP ;====================================================================== ; The strings are stored here in ASCIIZ form. ;---------------------------------------------------------------------- DB 0 STRINGS DB 26 DUP(0,0),0 ;They start empty STRING_END EQU $ PC = $ PC = PC + 256 STACK_TOP = PC LASTBYTE = PC CSEG ENDS END ENTPT