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Assembly Source File | 1988-11-30 | 48.6 KB | 1,695 lines

;====================================================================== ; TED.ASM -- The Tiny EDitor. ; PC Magazine * Tom Kihlken * tktktk ;---------------------------------------------------------------------- CSEG SEGMENT ASSUME CS:CSEG, DS:CSEG, ES:CSEG ORG 100H ;Beginning for .COM programs START: JMP BEGIN ;----------------------------------------------------------------------- ; Local data area ;----------------------------------------------------------------------- TAB EQU 9 CR EQU 13 LF EQU 10 LFCR EQU 0A0DH COPYRIGHT DB CR,LF,"TED 1.0 (c) 1988 Ziff Communications Co." DB CR,LF,"PC Magazine ",254," Tom Kihlken$",1AH FILE_TOO_BIG DB "File too big$" READ_ERR_MESS DB "Read error$" MEMORY_ERROR DB "Not enough memory$" PROMPT_STRING DB "1ABORT",0,"2UNDO",0,"3PRINT",0 DB "4MARK",0,"5CUT",0,"6PASTE",0,"7EXIT",0 DB "8DEL EOL",0,"9FIND",0,"10UDEL L",0,0 PROMPT_LENGTH = $ - OFFSET PROMPT_STRING SAVE_MESS DB "Save as: ",0 DOT_$$$ DB ".$$$",0 DOT_BAK DB ".BAK",0 SRCH_PROMPT DB "SEARCH STRING> ",0 SRCH_MAX DB 66 SRCH_SIZ DB 0 SRCH_STR DB 66 DUP (0) SRCH_FLG DB 0 SRCH_END DW 0 SRCH_BASE DW 0 SRCH_CLR DB 244 KP_CR DB 0 DIRTY_BITS DB 1 ORGATR DB 0 NORMAL DB 91 INVERSE DB 33 LEFT_MARGIN DB 0 MARGIN_COUNT DB 0 INSERT_MODE DB -1 MARK_MODE DB 0 ROWS DB 23 SAVE_COLUMN DB 0 SAVE_ROW DB 0 LINE_FLAG DB 0 EVEN NAME_POINTER DW 81H NAME_END DW 81H STATUS_REG DW ? VIDEO_SEG DW 0B000H LINE_LENGTH DW 0 UNDO_LENGTH DW 0 CUR_POSN DW 0 MARK_START DW 0FFFFH MARK_END DW 0 MARK_HOME DW 0 TOP_OF_SCREEN DW 0 CURSOR DW 0 LAST_CHAR DW 0 COLUMNSB LABEL BYTE COLUMNS DW ? PASTE_SEG DW ? PASTE_SIZE DW 0 PAGE_PROC DW ? OLDINT24 DD ? DISPATCH_TABLE DW OFFSET ABORT ,OFFSET UNDO ,OFFSET PRINT DW OFFSET MARK ,OFFSET CUT ,OFFSET PASTE DW OFFSET EXIT ,OFFSET DEL_EOL,OFFSET FIND_STR DW OFFSET UDEL_L ,OFFSET BAD_KEY,OFFSET BAD_KEY DW OFFSET HOME ,OFFSET UP ,OFFSET PGUP DW OFFSET BAD_KEY ,OFFSET LEFT ,OFFSET BAD_KEY DW OFFSET RIGHT ,OFFSET BAD_KEY,OFFSET ENDD DW OFFSET DOWN ,OFFSET PGDN ,OFFSET INSERT DW OFFSET DEL_CHAR ; The following machine instruction removes the desnow delay. It is ; inserted into the code for EGA, VGA, and MONO displays. NO_DESNOW = 0EBH + (OFFSET WRITE_IT - OFFSET HWAIT - 2) * 256 ;----------------------------------------------------------------------- ; We start by initialize the display, then allocate memory for the file ; and paste segments. Parse the command line for a filename, if one was ; input, read in the file. Finally set the INT 23 and 24 vectors. ;----------------------------------------------------------------------- BEGIN: XOR AX,AX MOV DS,AX ;Get a zero into DS ASSUME DS:NOTHING MOV AH,12H MOV BL,10H ;Get EGA info INT 10H CMP BL,10H ;Did BL change? JE NOT_EGA ;If not, no EGA in system TEST BYTE PTR DS:[0487H],8 ;Is EGA active? JNZ NOT_EGA MOV WORD PTR CS:HWAIT,NO_DESNOW ;Get rid of desnow MOV AX,DS:[0484H] ;Get number of rows DEC AL ;Last row is for prompt line MOV CS:[ROWS],AL ;Save the number of rows NOT_EGA: MOV AX,DS:[044AH] ;Get number of columns MOV CS:COLUMNS,AX ;and store it MOV AX,DS:[0463H] ;Address of display card ADD AX,6 ;Add six to get status port PUSH CS POP DS ASSUME DS:CSEG MOV STATUS_REG,AX CMP AX,3BAH ;Is this a MONO display? JNE COLOR ;If not, must be a CGA MOV WORD PTR HWAIT,NO_DESNOW ;Get rid of desnow JMP SHORT MOVE_STACK COLOR: MOV VIDEO_SEG,0B800H;Segment for color card XOR BH,BH ;Use page zero MOV AH,8 ;Get current attribute INT 10H MOV ORGATR,AH ;Save the original attribute MOVE_STACK: MOV BX,OFFSET NEW_STACK MOV SP,BX ;Move the stack downward ADD BX,15 MOV CL,4 ;Convert program size to SHR BX,CL ; paragraphs MOV AH,4AH ;Deallocate unused memory INT 21H MOV BX,1000H ;Request 64K for file segment MOV AH,48H INT 21H MOV ES,AX ASSUME ES:FILE_SEG MOV AH,48H INT 21H ;Request 64K for paste buffer JNC GOT_ENOUGH ;If enough memory, continue NOT_ENOUGH: MOV DX,OFFSET MEMORY_ERROR ERR_EXIT: PUSH CS POP DS MOV AH,9 ;Write the error message INT 21H ;DOS display service JMP EXIT_TO_DOS ;Exit this program GOT_ENOUGH: MOV PASTE_SEG,AX ;Use this for the paste buffer GET_FILENAME: MOV SI,80H ;Point to parameters MOV CL,[SI] ;Get number of characters XOR CH,CH ;Make it a word INC SI ;Point to first character PUSH SI ADD SI,CX ;Point to last character MOV BYTE PTR [SI],0 ;Make it an ASCII string MOV NAME_END,SI ;Save pointer to last character POP SI ;Get back pointer to filename CLD JCXZ NO_FILENAME ;If no params, just exit DEL_SPACES: LODSB ;Get character into AL CMP AL," " ;Is it a space? JNE FOUND_LETTER LOOP DEL_SPACES FOUND_LETTER: DEC SI ;Backup pointer to first letter MOV NAME_POINTER,SI ;Save pointer to filename MOV DX,SI MOV AX,3D00H ;Setup to open file INT 21H JC NO_FILENAME ;If we can't open, must be new file FILE_OPENED: PUSH ES POP DS ;DS has file segment also ASSUME DS:FILE_SEG MOV BX,AX ;Get the handle into BX XOR DX,DX ;Point to file buffer MOV AH,3FH ;Read service MOV CX,0FFFEH ;Read almost 64K bytes INT 21H MOV DI,AX ;Number of bytes read in JNC NO_RD_ERR ;If no error, take jump MOV DX,OFFSET READ_ERR_MESS JMP SHORT ERR_EXIT NO_RD_ERR: MOV LAST_CHAR,DI ;Save the file size CMP CX,AX ;Did the buffer fill? MOV DX,OFFSET FILE_TOO_BIG JE ERR_EXIT ;If yes, it is too big MOV AH,3EH INT 21H ;Close the file NO_FILENAME: PUSH ES PUSH ES ;Save file segment MOV AX,3524H ;Get INT 24 vector INT 21H MOV WORD PTR OLDINT24,BX ;Store the offset MOV WORD PTR OLDINT24+2,ES;And the segment PUSH CS POP DS MOV DX,OFFSET NEWINT24 ;Point to new vector MOV AX,2524H ;Now change INT 24 vector INT 21H MOV DX,OFFSET NEWINT23 MOV AX,2523H ;Set the INT 23 vector also INT 21H POP ES ;Get back file segment POP DS ASSUME DS:FILE_SEG, ES:FILE_SEG CALL REDO_PROMPT ;Draw the prompt line ;----------------------------------------------------------------------- ; Here's the main loop. It updates the screen, then reads a keystroke. ;----------------------------------------------------------------------- READ_A_KEY: CMP MARK_MODE,0 ;Is the mark state on? JE MARK_OFF ;If not, skip this OR DIRTY_BITS,4 ;Refresh the current row MOV DX,CUR_POSN CMP SAVE_ROW,DH ;Are we on the save row? JE SAME_ROW ;If yes, then redo the row only MOV DIRTY_BITS,1 ;Refresh the whole screen SAME_ROW: MOV AX,CURSOR ;Get cursor location MOV BX,MARK_HOME ;Get the anchor mark position CMP AX,BX ;Moving backward in file? JAE S1 MOV MARK_START,AX ;Switch start and end position MOV MARK_END,BX JMP SHORT MARK_OFF S1: MOV MARK_END,AX ;Store start and end marks MOV MARK_START,BX MARK_OFF: MOV DX,CUR_POSN MOV SAVE_ROW,DH CALL SET_CURSOR ;Position the cursor TEST DIRTY_BITS,1 ;Look at screen dirty bit JZ SCREEN_OK ;If zero, screen is OK MOV AH,1 ;Get keyboard status INT 16H ;Any keys ready? JNZ CURRENT_OK ;If yes, skip the update CALL DISPLAY_SCREEN ;Redraw the screen MOV DIRTY_BITS,0 ;Mark screen as OK SCREEN_OK: TEST DIRTY_BITS,4 ;Is the current line dirty? JZ CURRENT_OK ;If not, take jump CALL DISPLAY_CURRENT ;Redraw the current line MOV DIRTY_BITS,0 ;Mark screen as OK CURRENT_OK: MOV KP_CR,0 MOV AH,10H ;Read the next key INT 16H CMP SRCH_FLG,0 JE CKEXT MOV SRCH_FLG,0 MOV DIRTY_BITS,1 CKEXT: CMP AL,0 ;Is this an extended code? JE EXTENDED_CODE CMP AL,0E0H ;Is this an extended code? JNE DO_BAD CMP AH,0 JNE EXTENDED_CODE DO_BAD: CMP AH,0EH ;Was it the backspace key? JE BACK_SPACE CALL INSERT_KEY ;Put this character in the file JMP READ_A_KEY ;Get another key BACK_SPACE: CMP CURSOR,0 ;At start of file? JE BAD_KEY ;If at start, can't backspace CALL LEFT ;Move left one space CALL DEL_CHAR ;And delete the character JMP READ_A_KEY EXTENDED_CODE: MOV AL,0 CMP AH,84H ;Is it control PgUp? JNE NOT_TOP CALL TOP JMP READ_A_KEY NOT_TOP: CMP AH,76H ;Is it control PgDn? JNE NOT_BOTTOM CALL BOTTOM JMP READ_A_KEY BAD_KEY: MOV AL,AH JMP SHORT DO_BAD NOT_BOTTOM: CMP AH,66H ;Is it shift F9 JNE NOT_RPT CALL FIND_STR JMP READ_A_KEY NOT_RPT: CMP AH,73H ;Is it control left arrow? JE SH_LEFT CMP AH,74H ;Is it control right arrow? JE SH_RIGHT CMP AH,53H ;Skip high numbered keys JA BAD_KEY XCHG AH,AL SUB AL,3BH ;Also skip low numbered keys JC BAD_KEY SHL AX,1 ;Make the code an offset MOV BX,AX ;Put offset in BX CALL CS:DISPATCH_TABLE[BX] ;Call the key procedure JMP READ_A_KEY ;Then read another key ;----------------------------------------------------------------------- ; These two routines shift the display right or left to allow editing ; files which contain lines longer than 80 columns. ;----------------------------------------------------------------------- SH_RIGHT PROC NEAR CMP LEFT_MARGIN,255 - 8 ;Past max allowable margin? JAE NO_SHIFT ;Then can't move any more ADD LEFT_MARGIN,8 ;This moves the margin over SH_RETURN: CALL CURSOR_COL ;Compute column for cursor MOV DX,CUR_POSN MOV SAVE_COLUMN,DL ;Save the current column MOV DIRTY_BITS,1 ;Redraw the screen NO_SHIFT: JMP READ_A_KEY SH_RIGHT ENDP SH_LEFT PROC NEAR CMP LEFT_MARGIN,0 ;At start of line already? JE NO_SHIFT ;If yes, then don't shift SUB LEFT_MARGIN,8 ;Move the window over JMP SH_RETURN SH_LEFT ENDP ;----------------------------------------------------------------------- ; This moves the cursor to the top of the file. ;----------------------------------------------------------------------- TOP PROC NEAR XOR AX,AX ;Get a zero into AX MOV CURSOR,AX ;Cursor to start of file MOV TOP_OF_SCREEN,AX MOV LEFT_MARGIN,AL ;Move to far left margin MOV DIRTY_BITS,1 ;Redraw the screen MOV CUR_POSN,AX ;Home the cursor MOV SAVE_COLUMN,AL ;Save the cursor column RET TOP ENDP ;----------------------------------------------------------------------- ; This moves the cursor to the bottom of the file ;----------------------------------------------------------------------- BOTTOM PROC NEAR MOV DH,ROWS ;Get screen size MOV SI,LAST_CHAR ;Point to last character DEC SI MOV LEFT_MARGIN,0 ;Set window to start of line CALL LOCATE ;Adjust the screen position CALL HOME ;Move cursor to start of line MOV DIRTY_BITS,1 ;This will redraw the screen RET BOTTOM ENDP ;----------------------------------------------------------------------- ; Search for a string ;----------------------------------------------------------------------- FIND_STR PROC NEAR PUSH DS MOV BX,CS MOV DS,BX CMP AH,66H ;Is it shift F9 JE RPT_FIND MOV DH,ROWS INC DH ;Last row on the screen XOR DL,DL ;First column MOV SI,OFFSET SRCH_PROMPT CALL TTY_STRING ;Display search prompt MOV DX, OFFSET SRCH_MAX MOV AH,0Ah INT 21h ;Read input string RPT_FIND: XOR DX,DX MOV DL, BYTE PTR SRCH_SIZ ADD DX, OFFSET SRCH_STR MOV DI,DX DEC DI MOV SRCH_END,DI XOR DX,DX MOV SI,CURSOR INC SI MOV SRCH_BASE,SI S_REDO: MOV DI,OFFSET SRCH_STR MOV BX,SRCH_BASE S_CYCLE: MOV AL,[DI] MOV AH,AL ;CONVERT AL TO OPPOSITE AND PUT IN AH CMP AL,65 JB S_CMP CMP AL,90 JA TSTLO XOR AH,20H JMP SHORT S_CMP TSTLO: CMP AL,97 JB S_CMP XOR AH,20H S_CMP: CMP BX,LAST_CHAR JA END_MCH CMP AL,ES:[BX] JE S_MCH CMP AH,ES:[BX] JE S_MCH CMP DI,OFFSET SRCH_STR JNE S_REDO INC BX CMP WORD PTR ES:[BX]-1,LFCR JNE S_BX1 INC DL S_BX1: JMP SHORT S_CMP S_MCH: INC BX CMP DI,OFFSET SRCH_STR JNE NO_BSE MOV SRCH_BASE,BX NO_BSE: ADD DH,DL XOR DL,DL CMP DI,SRCH_END JE YEA_MCH INC DI JMP SHORT S_CYCLE YEA_MCH: MOV SRCH_FLG,1 MOV SI,SRCH_BASE DEC SI MOV SRCH_BASE,SI MOV CURSOR,SI XOR BX,BX MOV BL,BYTE PTR SRCH_SIZ ADD BX,SI MOV SRCH_END,BX XOR DL,DL ADD DX,CUR_POSN CMP DH,ROWS JBE NEW_S XOR DX,DX NEW_S: POP DS CALL LOCATE MOV DIRTY_BITS,1 ;This will redraw the screen CALL REDO_PROMPT RET END_MCH: POP DS CALL REDO_PROMPT RET FIND_STR ENDP ;----------------------------------------------------------------------- ; This deletes from the cursor position to the end of line. ;----------------------------------------------------------------------- DEL_EOL PROC NEAR MOV CX,CUR_POSN OR CL,CL ;At first column? JZ DEL_L ;If yes, then do line delete function MOV LINE_FLAG,0 PUSH CURSOR ;Save starting cursor location CALL ENDD ;Move the the end of line POP SI ;Get back starting cursor MOV CX,CURSOR ;Offset of the end of line MOV CURSOR,SI ;Restore starting cursor JMP DEL_END ;Delete characters to end DEL_EOL ENDP ;----------------------------------------------------------------------- ; This deletes a line, placing it in the line buffer. ;----------------------------------------------------------------------- DEL_L PROC NEAR MOV LINE_FLAG,1 CALL FIND_START ;Find start of this line MOV CURSOR,SI ;This will be the new cursor PUSH SI ;Save the cursor position CALL FIND_NEXT ;Find the next line MOV CX,SI ;CX will hold line length POP SI ;Get back new cursor location DEL_END: SUB CX,SI ;Number of bytes on line OR CH,CH ;Is line too long to fit JZ NOT_TOO_LONG MOV CX,100H ;Only save 256 characters NOT_TOO_LONG: MOV LINE_LENGTH,CX ;Store length of deleted line JCXZ NO_DEL_L MOV DI,OFFSET LINE_BUFFER ;Buffer for deleted line PUSH CX PUSH ES PUSH CS POP ES ;Line buffer is in CSEG REP MOVSB ;Put deleted line in buffer POP ES ;Get back file segment POP AX MOV CX,LAST_CHAR ;Get the file size SUB LAST_CHAR,AX ;Subtract the deleted line MOV SI,CURSOR ;Get new cursor location MOV DI,SI ADD SI,AX ;SI points to end of file SUB CX,SI ;Length of remaining file JCXZ NO_DEL_L REP MOVSB ;Shift remainder of file up NO_DEL_L: MOV DX,CUR_POSN ;Get cursor row/column MOV SI,CURSOR ;Get cursor offset CALL LOCATE ;Adjust the screen position MOV DIRTY_BITS,1 ;Redraw the screen RET DEL_L ENDP ;----------------------------------------------------------------------- ; This undeletes a line by copying it from the line buffer into the file ;----------------------------------------------------------------------- UDEL_L PROC NEAR CMP LINE_FLAG,0 ;Is this an end of line only? JE UDEL_EOL ;If yes, don't home the cursor CALL HOME ;Move cursor to home UDEL_EOL: MOV AX,LINE_LENGTH ;Length of deleted line MOV SI,OFFSET LINE_BUFFER JMP INSERT_STRING UDEL_L ENDP ;----------------------------------------------------------------------- ; These routines move the cursor left and right. ;----------------------------------------------------------------------- LEFT PROC NEAR CMP CURSOR,0 ;At start of file? JZ LR_NO_CHANGE ;Then can't move left MOV DX,CUR_POSN OR DL,DL ;At first column? JZ MOVE_UP ;If yes, then move up one DEC CURSOR ;Shift the cursor offset LR_RETURN: CALL CURSOR_COL ;Compute column for cursor MOV SAVE_COLUMN,DL ;Save the cursor column LR_NO_CHANGE: MOV UNDO_LENGTH,0 RET MOVE_UP: CALL UP ;Move up to next row JMP SHORT ENDD ;And move to end of line LEFT ENDP RIGHT PROC NEAR MOV SI,CURSOR CMP SI,LAST_CHAR ;At end of file? JE LR_NO_CHANGE ;If yes, then can't move CMP BYTE PTR [SI],CR;If CR JNE INC_RIGHT ;If yes, then test LF INC SI CMP SI,LAST_CHAR ;At end of file? DEC SI JE INC_RIGHT ;If yes, then increment CMP BYTE PTR [SI+1],LF;If LF JE MOVE_DOWN ;If yes, then move to next line INC_RIGHT: INC CURSOR ;Advance the cursor JMP LR_RETURN MOVE_DOWN: CALL HOME ;Move to start of line JMP DOWN ;And move down one row RIGHT ENDP ;----------------------------------------------------------------------- ; This moves the cursor to the start of the current line. ;----------------------------------------------------------------------- HOME PROC NEAR CALL FIND_START ;Find start of line MOV CURSOR,SI ;Save the new cursor MOV SAVE_COLUMN,0 ;Save the cursor column MOV BYTE PTR CUR_POSN,0 ;Store column number RET HOME ENDP ;----------------------------------------------------------------------- ; This moves the cursor to the end of the current line ;----------------------------------------------------------------------- ENDD PROC NEAR MOV SI,CURSOR CALL FIND_EOL ;Find end of this line MOV CURSOR,SI ;Store the new cursor CALL CURSOR_COL ;Compute the correct column MOV SAVE_COLUMN,DL ;Save the cursor column RET ENDD ENDP ;----------------------------------------------------------------------- ; This moves the cursor up one row. If the cursor is at the first row, ; the screen is scrolled down. ;----------------------------------------------------------------------- UP PROC NEAR MOV UNDO_LENGTH,0 MOV DX,CUR_POSN MOV SI,CURSOR OR DH,DH ;At top row already? JZ SCREEN_DN ;If yes, then scroll down DEC DH ;Move cursor up one row CALL FIND_CR ;Find the beginning of this row MOV CURSOR,SI CALL FIND_START ;Find start of this row MOV CURSOR,SI CALL SHIFT_RIGHT ;Skip over to current column AT_TOP: RET SCREEN_DN: MOV SI,TOP_OF_SCREEN OR SI,SI ;At start of file? JZ AT_TOP ;If at top, then do nothing CALL FIND_PREVIOUS ;Find the preceeding line MOV TOP_OF_SCREEN,SI;Save new top of screen MOV SI,CURSOR CALL FIND_PREVIOUS ;Find the preceeding line MOV CURSOR,SI ;This is the new cursor SHIFT_RET: MOV DIRTY_BITS,1 ;Need to redraw screen MOV SI,CURSOR MOV DX,CUR_POSN JMP SHIFT_RIGHT ;Move cursor to current column UP ENDP ;----------------------------------------------------------------------- ; This moves the cursor down one row. When the last row is reached, ; the screen is shifted up one row. ;----------------------------------------------------------------------- DOWN PROC NEAR MOV UNDO_LENGTH,0 MOV DX,CUR_POSN CMP DH,ROWS ;At bottom row already? MOV SI,CURSOR ;Get position in file JE SCREEN_UP ;If at bottom, then scroll up CALL FIND_NEXT ;Find the start of next line JC DOWN_RET ;If no more lines, then return MOV CURSOR,SI INC DH ;Advance cursor to next row CALL SHIFT_RIGHT ;Move cursor to current column DOWN_RET: RET SCREEN_UP: CMP SI,LAST_CHAR ;Get cursor offset JE DOWN_RET CALL FIND_START ;Find the start of this line MOV CURSOR,SI ;This is the new cursor CALL FIND_NEXT ;Find the offset of next line JC SHIFT_RET ;If no more lines then return MOV CURSOR,SI ;This is the new cursor MOV SI,TOP_OF_SCREEN;Get the start of the top row CALL FIND_NEXT ;And find the next line MOV TOP_OF_SCREEN,SI;Store the new top of screen JMP SHIFT_RET DOWN ENDP ;----------------------------------------------------------------------- ; These two routines move the screen one page at a time by calling the ; UP and DOWN procedures. ;----------------------------------------------------------------------- PGDN PROC NEAR MOV PAGE_PROC,OFFSET DOWN PAGE_UP_DN: MOV CL,ROWS ;Get length of the screen SUB CL,5 ;Don't page a full screen XOR CH,CH ;Make it a word PAGE_LOOP: PUSH CX CALL PAGE_PROC ;Move the cursor down POP CX LOOP PAGE_LOOP ;Loop for one page length RET PGDN ENDP PGUP PROC NEAR MOV PAGE_PROC,OFFSET UP JMP PAGE_UP_DN PGUP ENDP ;----------------------------------------------------------------------- ; This toggles the insert/overstrike mode. ;----------------------------------------------------------------------- INSERT PROC NEAR NOT INSERT_MODE ;Toggle the switch JMP REDO_PROMPT ;Redraw the insert status INSERT ENDP ;----------------------------------------------------------------------- ; This deletes the character at the cursor by shifting the remaining ; characters forward. ;----------------------------------------------------------------------- DEL_CHAR PROC NEAR MOV CX,LAST_CHAR MOV SI,CURSOR MOV DI,SI CMP SI,CX ;Are we at end of file? JAE NO_DEL ;If yes, then don't delete LODSB CALL SAVE_CHAR ;Save it for UNDO function MOV AH,[SI] ;Look at the next character also PUSH AX ;Save character were deleting DEC LAST_CHAR ;Shorten the file by one SUB CX,SI REP MOVSB ;Move file down one notch POP AX ;Get back character we deleted CMP AL,CR ;Did we delete a CR? JE COMBINE OR DIRTY_BITS,4 ;Current line is dirty NO_DEL: RET COMBINE: CMP AH,LF ;Was the next character a LF? JNE NO_DEL_LF CALL DEL_CHAR ;Now delete the line feed NO_DEL_LF: CALL DISPLAY_BOTTOM ;Repaint bottom of the screen MOV DX,CUR_POSN MOV SAVE_COLUMN,DL ;Save the cursor column RET DEL_CHAR ENDP ;----------------------------------------------------------------------- ; This toggles the mark state and resets the paste buffer pointers. ;----------------------------------------------------------------------- MARK PROC NEAR XOR AX,AX NOT MARK_MODE ;Toggle the mode flag CMP MARK_MODE,AL ;Turning mode ON? JNE MARK_ON MOV DIRTY_BITS,1 ;Need to redraw the screen MOV MARK_START,0FFFFH JMP SHORT MARK_RET MARK_ON: MOV AX,CURSOR ;Get the cursor offset MOV MARK_START,AX ;Start of marked range MARK_RET: MOV MARK_END, AX ;End of marked range MOV MARK_HOME, AX ;Center of marked range RET MARK ENDP ;----------------------------------------------------------------------- ; This removes the marked text and places it in the paste buffer ;----------------------------------------------------------------------- CUT PROC NEAR CMP MARK_MODE,0 ;Is the mark mode on? JE NO_MARK ;If not, then do nothing MOV CX,MARK_END ;Get end of mark region MOV SI,MARK_START ;Get start of mark region SUB CX,SI ;Number of bytes selected MOV PASTE_SIZE,CX JCXZ NO_MARK XOR DI,DI ;Point to paste bufferf PUSH CX PUSH ES MOV ES,PASTE_SEG ;Get the paste segment REP MOVSB ;Put deleted text in buffer POP ES POP AX MOV CX,LAST_CHAR SUB LAST_CHAR,AX ;Shorten the file this much MOV DI,MARK_START MOV SI,MARK_END SUB CX,SI JCXZ NO_DELETE REP MOVSB ;Shorten the file NO_DELETE: MOV DX,CUR_POSN MOV SI,MARK_START CALL LOCATE ;Adjust the screen position CALL MARK ;This turns off select NO_MARK: RET CUT ENDP ;----------------------------------------------------------------------- ; This copies the paste buffer into the file at the cursor location ;----------------------------------------------------------------------- PASTE PROC NEAR MOV AX,PASTE_SIZE ;Number of characters in buffer OR AX,AX ;Any there? JZ NO_PASTE ;If not, nothing to paste MOV SI,CURSOR ;Get cursor location PUSH AX PUSH SI CALL OPEN_SPACE ;Make room for new characters POP DI POP CX JC NO_PASTE ;If no room, just exit XOR SI,SI ;Point to paste buffer PUSH DS MOV DS,PASTE_SEG ;Segment of paste buffer REP MOVSB ;Copy in the new characters POP DS MOV SI,DI MOV CURSOR,SI ;Cursor moved to end of insert MOV DX,CUR_POSN ;Get current cursor row CALL LOCATE ;Adjust the screen position MOV DIRTY_BITS,1 ;Redraw the screen NO_PASTE: RET PASTE ENDP ;----------------------------------------------------------------------- ; This prints the marked text. If printer fails, it is canceled. ;----------------------------------------------------------------------- PRINT PROC NEAR CMP MARK_MODE,0 ;Is mark mode on? JE PRINT_RET ;If not, nothing to print MOV CX,MARK_END ;End of marked region MOV SI,MARK_START ;Start of marked region SUB CX,SI ;Number of bytes selected JCXZ PRINT_DONE ;If nothing to print, return MOV AH,2 XOR DX,DX ;Select printer 0 INT 17H ;Get printer status TEST AH,10000000B ;Is busy bit set? JZ PRINT_DONE TEST AH,00100000B ;Is printer out of paper? JNZ PRINT_DONE PRINT_LOOP: LODSB XOR AH,AH INT 17H ;Print the character ROR AH,1 ;Check time out bit JC PRINT_DONE ;If set, quit printing LOOP PRINT_LOOP MOV AL,CR XOR AH,0 INT 17H ;Finish with a CR PRINT_DONE: CALL MARK ;Turn off the mark state PRINT_RET: RET PRINT ENDP ;----------------------------------------------------------------------- ; This command restores any characters which have recently been deleted. ;----------------------------------------------------------------------- UNDO PROC NEAR XOR AX,AX XCHG AX,UNDO_LENGTH ;Get buffer length MOV SI,OFFSET UNDO_BUFFER JMP INSERT_STRING UNDO ENDP ;----------------------------------------------------------------------- ; This inserts AX characters from CS:SI into the file. ;----------------------------------------------------------------------- INSERT_STRING PROC NEAR PUSH SI ;Save string buffer MOV SI,CURSOR ;Get cursor offset PUSH AX ;Save length of string PUSH SI CALL OPEN_SPACE ;Make space to insert string POP DI ;Get back cursor position POP CX ;Get back string length POP SI ;Get back string buffer JC NO_SPACE ;If no space available, exit PUSH DS PUSH CS POP DS ASSUME DS:CSEG REP MOVSB ;Copy the characters in MOV SI,CURSOR ;Get the new cursor offset MOV DX,CUR_POSN ;Also get the current row MOV DIRTY_BITS,1 ;And redraw the screen POP DS ASSUME DS:NOTHING CALL LOCATE ;Adjust the screen position NO_SPACE: RET INSERT_STRING ENDP ;----------------------------------------------------------------------- ; This adds a character to the undo buffer. ;----------------------------------------------------------------------- SAVE_CHAR PROC NEAR MOV BX,UNDO_LENGTH OR BH,BH ;Is buffer filled? JNZ NO_SAVE INC UNDO_LENGTH MOV BYTE PTR CS:UNDO_BUFFER[BX],AL NO_SAVE: RET SAVE_CHAR ENDP ;----------------------------------------------------------------------- ; This prompts for a verify keystroke then exits without saving the file ;----------------------------------------------------------------------- ABORT PROC NEAR ASSUME DS:CSEG PUSH CS POP DS MOV DH,ROWS ;Last row on display INC DH ;Bottom row of screen XOR DL,DL ;First column FINISHED: MOV AH,ORGATR MOV NORMAL,AH ;Go back to black and white MOV DH,ROWS ;Move to last row on screen XOR DL,DL ;And column zero CALL SET_CURSOR INC DH CALL ERASE_EOL ;Erase the last row EXIT_TO_DOS: PUSH CS POP DS ;Point to code segment MOV AX,4C00H INT 21H ABORT ENDP ;----------------------------------------------------------------------- ; This prompts for a filename then writes the file. The original file ; is renamed to filename.BAK. If an invalid filename is entered, the ; speaker is beeped. ;----------------------------------------------------------------------- EXIT PROC NEAR PUSH DS PUSH ES MOV AX,CS MOV DS,AX MOV ES,AX ASSUME DS:CSEG, ES:CSEG NEXT_LETTER: MOV DH,ROWS INC DH ;Last row on the screen XOR DL,DL ;First column MOV SI,OFFSET SAVE_MESS PUSH DX CALL TTY_STRING ;Display a prompt POP DX ADD DL,9 ;Move right 9 spaces MOV SI,NAME_POINTER CALL TTY_STRING ;Display the filename XOR AH,AH ;Read the next key INT 16H MOV DI,NAME_END ;This points to last letter OR AL,AL ;Is it a real character? JZ NEXT_LETTER ;Ignore special keys CMP AL,27 ;Is it escape? JNE NOT_ESCAPE MOV DIRTY_BITS,1 ;Redraw the screen POP ES ;Get back file segments POP DS JMP REDO_PROMPT ;Redraw the prompt NOT_ESCAPE: CMP AL,CR ;Is it CR? JE GOT_NAME CMP AL,8 ;Is it a backspace? JNE NORMAL_LETTER CMP DI,NAME_POINTER ;At first letter? JLE NEXT_LETTER ;If yes, dont erase it MOV BYTE PTR [DI-1],0 DEC NAME_END JMP NEXT_LETTER NORMAL_LETTER: CMP DI,81H + 65 ;Too many letters? JG NEXT_LETTER ;If yes, ignore them XOR AH,AH STOSW ;Store the new letter INC NAME_END ;Name is one character longer JMP NEXT_LETTER ;Read another keystroke GOT_NAME: MOV DX,NAME_POINTER ;Point to the filename MOV AX,4300H ;Get the files attribute INT 21H JNC NAME_OK ;If no error, filename is OK CMP AX,3 ;Was it path not found error? JE BAD_NAME ;If yes, filename was bad NAME_OK: MOV SI,OFFSET DOT_$$$ ;Point to the ".$$$" MOV DI,OFFSET NAME_DOT_$$$ CALL CHG_EXTENSION ;Add the new extension MOV DX,OFFSET NAME_DOT_$$$ ;Point to the temp filename MOV AH,3CH ;Function to create file MOV CX,0020H ;Attribute for new file INT 21H ;Try to create the file JNC NAME_WAS_OK ;Continue if name was OK BAD_NAME: MOV AX,0E07H ;Write a bell character INT 10H ;BIOS tty service JMP NEXT_LETTER ;Get another letter WRITE_ERROR: MOV AH,3EH ;Close the file INT 21H JMP BAD_NAME ;Filename must be bad NAME_WAS_OK: XOR DX,DX ;This is the file buffer MOV CX,LAST_CHAR ;Number of chars in file MOV DI,CX MOV BX,AX ;This is the handle MOV AH,40H ;Write to the file POP DS ;Recover buffer segment INT 21H ;Write the buffer contents POP DS JC WRITE_ERROR ;Exit on a write error CMP AX,CX ;Was entire file written? JNE WRITE_ERROR ;If not, exit PUSH CS POP DS ;Get the code segment MOV AH,3EH INT 21H ;Close the temp file MOV SI,OFFSET DOT_BAK ;Point to the ".BAK" MOV DI,OFFSET NAME_DOT_BAK CALL CHG_EXTENSION ;Make the backup filename MOV DX,OFFSET NAME_DOT_BAK ;Point to the backup name MOV AH,41H INT 21H ;Delete existing backup file MOV DI,OFFSET NAME_DOT_BAK MOV DX,NAME_POINTER MOV AH,56H INT 21H MOV DI,NAME_POINTER ;Point to new filename MOV DX,OFFSET NAME_DOT_$$$ ;Point to temporary file MOV AH,56H ;Rename temp to new file INT 21H ;DOS function to rename POP AX ;Restore the stack POP AX JMP FINISHED EXIT ENDP ;----------------------------------------------------------------------- ; This subroutine displays a character by writing directly ; to the screen buffer. To avoid screen noise (snow) on the color ; card, the horizontal retrace has to be monitored. ;----------------------------------------------------------------------- WRITE_INVERSE PROC NEAR ASSUME DS:FILE_SEG, ES:FILE_SEG MOV BH,INVERSE ;Attribute for inverse video JMP SHORT WRITE_SCREEN WRITE_NORMAL: MOV BH,NORMAL ;Attribute for normal video JMP SHORT WRITE_SCREEN WRITE_FIND: MOV BH,SRCH_CLR ;Attribute for find string WRITE_SCREEN: MOV BL,AL ;Save the character PUSH ES MOV DX,STATUS_REG ;Retrieve status register MOV ES,VIDEO_SEG ;Get segment of video buffer HWAIT: IN AL,DX ;Get video status ROR AL,1 ;Look at horizontal retrace JNC HWAIT ;Wait for retrace WRITE_IT: MOV AX,BX ;Get the character/attribute STOSW ;Write the character POP ES RET WRITE_INVERSE ENDP ;----------------------------------------------------------------------- ; This moves the cursor to the row/column in DX. ;----------------------------------------------------------------------- SET_CURSOR PROC NEAR XOR BH,BH ;Were using page zero MOV AH,2 ;BIOS set cursor function INT 10H RET SET_CURSOR ENDP ;----------------------------------------------------------------------- ; This computes the video buffer offset for the row/column in DX ;---------------------------------------------------------------------- POSITION PROC NEAR MOV AX,COLUMNS ;Take columns per row MUL DH ;Times row number XOR DH,DH ADD AX,DX ;Add in the column number SHL AX,1 ;Times 2 for offset MOV DI,AX ;Return result in DI RET POSITION ENDP ;----------------------------------------------------------------------- ; This erases from the location in DX to the right edge of the screen ;----------------------------------------------------------------------- ERASE_EOL PROC NEAR CALL POSITION ;Find screen offset MOV CX,COLUMNS ;Get screen size SUB CL,DL ;Subtract current position JCXZ NO_CLEAR ERASE_LOOP: MOV AL," " ;Write blanks to erase CALL WRITE_NORMAL ;Display it LOOP ERASE_LOOP NO_CLEAR: RET ERASE_EOL ENDP ;----------------------------------------------------------------------- ; This displays the function key prompt and insert mode state ;----------------------------------------------------------------------- REDO_PROMPT PROC NEAR ASSUME DS:NOTHING, ES:NOTHING PUSH DS PUSH CS POP DS ASSUME DS:CSEG MOV DH,ROWS ;Put prompt at last row INC DH XOR DL,DL ;And column 0 CALL POSITION ;Convert to screen offset MOV SI,OFFSET PROMPT_STRING KEY_LOOP: MOV AL,"F" ;Display an "F" CALL WRITE_NORMAL LODSB OR AL,AL ;Last key in prompt? JZ PROMPT_DONE CALL WRITE_NORMAL CMP BYTE PTR CS:[SI],"0" ;Is it F10? JNE TEXT_LOOP LODSB CALL WRITE_NORMAL TEXT_LOOP: LODSB OR AL,AL ;Last letter in word? JNZ WRITE_CHAR MOV AL," " ;Display a space CALL WRITE_NORMAL JMP KEY_LOOP WRITE_CHAR: CALL WRITE_INVERSE ;Display the letter JMP TEXT_LOOP ;Do the next letter PROMPT_DONE: MOV DH,ROWS INC DH ;Get to last row on screen MOV DL,PROMPT_LENGTH + 9 CALL ERASE_EOL ;Erase to the end of this row MOV AL,"O" ;Write an "O" CMP INSERT_MODE,0 ;In insert mode? JE OVERSTRIKE MOV AL,"I" ;Write an "I" OVERSTRIKE: DEC DI ;Backup one character position DEC DI CALL WRITE_NORMAL POP DS RET REDO_PROMPT ENDP ;----------------------------------------------------------------------- ; This displays the file buffer on the screen. ;----------------------------------------------------------------------- DISPLAY_SCREEN PROC NEAR ASSUME DS:FILE_SEG, ES:FILE_SEG MOV SI,TOP_OF_SCREEN;Point to first char on screen XOR DH,DH ;Start at first row JMP SHORT NEXT_ROW DISPLAY_BOTTOM: ;This redraws the bottom only CALL FIND_START ;Find first character on this row MOV DX,CUR_POSN ;Get current cursor row NEXT_ROW: PUSH DX CALL DISPLAY_LINE ;Display a line POP DX INC DH ;Move to the next row CMP DH,ROWS ;At end of screen yet? JBE NEXT_ROW ;Do all the rows RET DISPLAY_SCREEN ENDP ;----------------------------------------------------------------------- ; This subroutine displays a single line to the screen. DH holds the ; row number, SI has the offset into the file buffer. Tabs are expanded. ; Adjustment is made for side shift. ;----------------------------------------------------------------------- DISPLAY_CURRENT PROC NEAR CALL FIND_START MOV DX,CUR_POSN DISPLAY_LINE: XOR DL,DL ;Start at column zero MOV MARGIN_COUNT,DL MOV CX,DX ;Use CL to count the columns CALL POSITION ;Compute offset into video NEXT_CHAR: CMP SI,LAST_CHAR ;At end of file? JAE LINE_DONE LODSB ;Get next character CMP AL,CR ;Is it a carriage return? JE FOUND_CR ;Quit when a CR is found CMP AL,TAB ;Is this a Tab character JE EXPAND_TAB ;If yes, expand to spaces DO_PUT: CALL PUT_CHAR ;Put character onto screen TAB_DONE: CMP CL,COLUMNSB ;At right edge of screen? JB NEXT_CHAR LN_OVF: CMP BYTE PTR [SI],CR JNE DO_DIA INC SI CMP SI,LAST_CHAR ;At end of file? JAE NOT_BEYOUND CMP BYTE PTR [SI],LF;Is this the end of the line? DEC SI JE NOT_BEYOUND DO_DIA: DEC DI ;Backup one character DEC DI MOV AL,4 ;Show a diamond CALL WRITE_INVERSE ;In inverse video NOT_BEYOUND: JMP FIND_NEXT ;Find start of next line FOUND_CR: LODSB ;Look at the next character CMP AL,LF ;Is it a line feed? JE LINE_DONE MOV AL,CR DEC SI JMP SHORT DO_PUT LINE_DONE: MOV DX,CX JMP ERASE_EOL ;Erase the rest of the line EXPAND_TAB: MOV AL," " ;Convert Tabs to spaces CALL PUT_CHAR MOV AL,MARGIN_COUNT ADD AL,CL TEST AL,00000111B ;At even multiple of eight? JNZ EXPAND_TAB ;If not keep adding spaces JMP TAB_DONE DISPLAY_CURRENT ENDP ;----------------------------------------------------------------------- ; This displays a single character to the screen. If the character is ; marked, it is shown in inverse video. Characters outside the current ; margin are not displayed. Characters left of the margin are skipped. ;----------------------------------------------------------------------- PUT_CHAR PROC NEAR MOV BL,MARGIN_COUNT ;Get distance to left margin CMP BL,LEFT_MARGIN ;Are we inside left margin? JAE IN_WINDOW ;If yes, show the character INC BL MOV MARGIN_COUNT,BL RET IN_WINDOW: CMP SRCH_FLG,0 JE CKM CMP SI,SRCH_BASE JBE CKM CMP SI,SRCH_END JA CKM CALL WRITE_FIND JMP SHORT NEXT_COL CKM: CMP SI,MARK_START ;Is this character marked? JBE NOT_MARKED CMP SI,MARK_END JA NOT_MARKED CALL WRITE_INVERSE ;Marked characters shown inverse JMP SHORT NEXT_COL NOT_MARKED: CALL WRITE_NORMAL NEXT_COL: INC CL ;Increment the column count RET PUT_CHAR ENDP ;----------------------------------------------------------------------- ; This routine adds a character into the file. In insert mode, remaining ; characters are pushed forward. If a CR is inserted, a LF is added also. ;----------------------------------------------------------------------- INSERT_KEY PROC NEAR MOV SI,CURSOR CMP AL,CR ;Was this a carriage return JNE CK_INS CMP AH,1CH JE NEW_LINE CK_INS: MOV SI,CURSOR CMP INSERT_MODE,0 ;In insert mode? JNE INSERT_CHAR CMP SI,LAST_CHAR ;At end of file? JE INSERT_CHAR CMP BYTE PTR [SI],CR INC SI CMP SI,LAST_CHAR ;At end of file? DEC SI JE INSERT_CHAR CMP BYTE PTR [SI+1],LF;At end of line? JE INSERT_CHAR MOV DI,SI XCHG DS:[SI],AL ;Switch new character for old one CALL SAVE_CHAR ;Store the old character JMP SHORT ADVANCE INSERT_CHAR: PUSH SI PUSH AX ;Save the new character MOV AX,1 CALL OPEN_SPACE ;Make room for it POP AX ;Get back the new character POP DI JC FILE_FULL STOSB ;Insert character in file buffer ADVANCE: OR DIRTY_BITS,4 ;Current line is dirty PUSH UNDO_LENGTH CALL RIGHT ;Move cursor to next letter POP UNDO_LENGTH FILE_FULL: RET NEW_LINE: PUSH SI MOV AX,2 CALL OPEN_SPACE ;Make space for CR and LF POP DI ;Get back old cursor location JC FILE_FULL MOV AX,LF*256+CR STOSW ;Store the CR and LF CALL DISPLAY_BOTTOM ;Repaint bottom of the screen CALL HOME ;Cursor to start of line JMP DOWN ;Move down to the new line INSERT_KEY ENDP ;----------------------------------------------------------------------- ; This subroutine inserts spaces into the file buffer. On entry AX ; contains the number of spaces to be inserted. On return, CF=1 if ; there was not enough space in the file buffer. ;----------------------------------------------------------------------- OPEN_SPACE PROC NEAR MOV CX,LAST_CHAR ;Last character in the file MOV SI,CX MOV DI,CX ADD DI,AX ;Offset for new end of file JC NO_ROOM ;If no more room, return error MOV LAST_CHAR,DI ;Save offset of end of file SUB CX,CURSOR ;Number of characters to shift DEC DI DEC SI STD ;String moves goes forward REP MOVSB ;Shift the file upward CLD CLC NO_ROOM: RET OPEN_SPACE ENDP ;----------------------------------------------------------------------- ; This subroutine adjusts the cursor position ahead to the saved cursor ; column. On entry DH has the cursor row. ;----------------------------------------------------------------------- SHIFT_RIGHT PROC NEAR MOV CL,SAVE_COLUMN ;Keep the saved cursor offset XOR CH,CH MOV BP,CX ;Keep the saved cursor position ADD CL,LEFT_MARGIN ;Shift into visable window also ADC CH,0 XOR DL,DL MOV CUR_POSN,DX ;Get cursor row/column JCXZ NO_CHANGE RIGHT_AGAIN: PUSH CX CMP BYTE PTR [SI],CR;At end of line? JE DONT_MOVE ;If at end, stop moving CALL RIGHT ;Move right one character DONT_MOVE: POP CX MOV AL,SAVE_COLUMN XOR AH,AH CMP AX,CX ;Is cursor still in margin? JL IN_MARGIN ;If yes, keep moving MOV DX,CUR_POSN ;Get cursor column again XOR DH,DH CMP DX,BP ;At saved cursor position? JE RIGHT_DONE ;If yes, were done JA RIGHT_TOO_FAR ;Did we go too far? IN_MARGIN: LOOP RIGHT_AGAIN RIGHT_DONE: MOV CX,BP MOV SAVE_COLUMN,CL ;Get back saved cursor position NO_CHANGE: RET RIGHT_TOO_FAR: CALL LEFT ;Move back left one place MOV CX,BP MOV SAVE_COLUMN,CL ;Get back saved cursor position RET SHIFT_RIGHT ENDP ;----------------------------------------------------------------------- ; This subroutine skips past the CR and LF at SI. SI returns new offset ;----------------------------------------------------------------------- SKIP_CR_LF PROC NEAR CMP SI,LAST_CHAR ;At last char in the file? JAE NO_SKIP ;If yes, dont skip anything CMP BYTE PTR [SI],CR;Is first character a CR? JNE NO_SKIP INC SI ;Look at next character CMP SI,LAST_CHAR ;Is it at the end of file? JAE NO_SKIP ;If yes, dont skip anymore CMP BYTE PTR [SI],LF;Is next character a line feed? JNE NO_SKIP ;Skip any line feeds also INC SI NO_SKIP: RET SKIP_CR_LF ENDP ;----------------------------------------------------------------------- ; This subroutine finds the beginning of the previous line. ;----------------------------------------------------------------------- FIND_PREVIOUS PROC NEAR PUSH CURSOR ;Save the cursor location CALL FIND_CR ;Find start of this line MOV CURSOR,SI ;Save the new cursor CALL FIND_START ;Find the start of this line POP CURSOR ;Get back starting cursor RET FIND_PREVIOUS ENDP ;----------------------------------------------------------------------- ; This searches for the previous carriage return. Search starts at SI. ;----------------------------------------------------------------------- FIND_CR PROC NEAR PUSH CX MOV AL,LF ;Look for a carriage return MOV DI,SI MOV CX,SI JCXZ AT_BEGINNING DEC DI STD ;Search backwards LF_PREV: REPNE SCASB ;Scan for the character JCXZ LF_END CMP BYTE PTR [DI],CR JNE LF_PREV DEC DI LF_END: CLD ;Restore direction flag INC DI MOV SI,DI AT_BEGINNING: POP CX RET FIND_CR ENDP ;----------------------------------------------------------------------- ; This subroutine computes the location of the start of current line. ; Returns SI pointing to the first character of the current line. ;----------------------------------------------------------------------- FIND_START PROC NEAR MOV SI,CURSOR ;Get the current cursor OR SI,SI ;At start of the file? JZ AT_START ;If yes, were done CALL FIND_CR ;Find the CALL SKIP_CR_LF AT_START: RET FIND_START ENDP ;----------------------------------------------------------------------- ; This finds the offset of the start of the next line. The search is ; started at location ES:SI. On return CF=1 of no CR was found. ;----------------------------------------------------------------------- FIND_NEXT PROC NEAR PUSH CX CALL FIND_EOL ;Find the end of this line JC AT_NEXT ;If at end of file, return CALL SKIP_CR_LF ;Skip past CR and LF CLC ;Indicate end of line found AT_NEXT: POP CX RET FIND_NEXT ENDP ;----------------------------------------------------------------------- ; This searches for the next carriage return in the file. The search ; starts at the offset in register SI. ;----------------------------------------------------------------------- FIND_EOL PROC NEAR MOV AL,CR ;Look for a carriage return CR_SCAN: MOV CX,LAST_CHAR ;Last letter in the file SUB CX,SI ;Count for the search MOV DI,SI JCXZ AT_END ;If nothing to search, return REPNE SCASB ;Scan for the character MOV SI,DI ;Return the location of the CR JCXZ AT_END ;If not found, return CMP BYTE PTR [SI],LF JNE CR_SCAN DEC SI CLC ;Indicate the CR was found RET AT_END: STC ;Indicate CR was not found RET FIND_EOL ENDP ;----------------------------------------------------------------------- ; This subroutine positions the screen with the cursor at the row ; selected in register DH. On entry, SI holds the cursor offset. ;----------------------------------------------------------------------- LOCATE PROC NEAR MOV CL,DH XOR CH,CH MOV CURSOR,SI XOR DX,DX ;Start at top of the screen OR SI,SI ;At start of buffer? JZ LOCATE_FIRST CALL FIND_START ;Get start of this row XOR DX,DX ;Start at top of the screen OR SI,SI ;Is cursor at start of file? JZ LOCATE_FIRST JCXZ LOCATE_FIRST ;If locating to top row were done FIND_TOP: PUSH SI PUSH CX CALL FIND_CR ;Find previous row POP CX POP AX CMP BYTE PTR [SI],CR JNE LOCATE_FIRST CMP BYTE PTR [SI+1],LF JNE LOCATE_FIRST CMP SI,AX ;Did it change? JE LOCATE_DONE ;If not, quit moving INC DH ;Cursor moves to next row LOOP FIND_TOP LOCATE_DONE: PUSH CURSOR MOV CURSOR,SI CALL FIND_START ;Find start of top of screen POP CURSOR LOCATE_FIRST: MOV TOP_OF_SCREEN,SI MOV CUR_POSN,DX CALL CURSOR_COL MOV SAVE_COLUMN,DL RET LOCATE ENDP ;----------------------------------------------------------------------- ; This subroutine computes the correct column for the cursor. No ; inputs. On exit, CUR_POSN is set and DX has the row/column. ;----------------------------------------------------------------------- CURSOR_COL PROC NEAR MOV SI,CURSOR ;Get cursor offset CALL FIND_START ;Find start of this line MOV CX,CURSOR SUB CX,SI MOV DX,CUR_POSN ;Get current row XOR DL,DL ;Start at column zero MOV MARGIN_COUNT,DL ;Count past the left margin JCXZ COL_DONE CURSOR_LOOP: LODSB ;Get the next character CMP AL,CR ;Is it the end of line? JNE NOT_EOL CMP BYTE PTR [SI],LF JE COL_DONE ;If end, were done NOT_EOL: CMP AL,TAB ;Is it a tab? JNE NOT_A_TAB MOV BL,MARGIN_COUNT OR BL,00000111B MOV MARGIN_COUNT,BL CMP BL,LEFT_MARGIN ;Inside visible window yet? JB NOT_A_TAB ;If not, don't advance cursor OR DL,00000111B ;Move to multiple of eight NOT_A_TAB: MOV BL,MARGIN_COUNT INC BL MOV MARGIN_COUNT,BL CMP BL,LEFT_MARGIN JBE OUT_OF_WINDOW INC DL ;Were at next column now OUT_OF_WINDOW: LOOP CURSOR_LOOP COL_DONE: CMP DL,COLUMNSB ;Past end of display? JB COLUMN_OK ;If not, were OK? MOV DL,COLUMNSB DEC DL ;Leave cursor at last column COLUMN_OK: MOV CUR_POSN,DX ;Store the row/column RET CURSOR_COL ENDP ;----------------------------------------------------------------------- ; This displays the string at CS:SI at the location in DX. The ; remainder of the row is erased. Cursor is put at the end of the line. ;----------------------------------------------------------------------- TTY_STRING PROC NEAR ASSUME DS:CSEG PUSH DX CALL POSITION ;Compute offset into video POP DX TTY_LOOP: LODSB OR AL,AL ;At end of string yet? JZ TTY_DONE INC DL PUSH DX CALL WRITE_INVERSE ;Write in inverse video POP DX JMP TTY_LOOP TTY_DONE: CALL SET_CURSOR ;Move cursor to end of string JMP ERASE_EOL ;Erase the rest of line TTY_STRING ENDP ;----------------------------------------------------------------------- ; This copies the input filename to CS:DI and changes the extension ;----------------------------------------------------------------------- CHG_EXTENSION PROC NEAR ASSUME DS:CSEG, ES:CSEG PUSH SI MOV SI,NAME_POINTER CHG_LOOP: LODSB CMP AL,"." ;Look for the extension JE FOUND_DOT OR AL,AL JZ FOUND_DOT STOSB ;Copy a character JMP CHG_LOOP FOUND_DOT: MOV CX,5 ;Five chars in extension POP SI REP MOVSB ;Move new extension in RET CHG_EXTENSION ENDP ;----------------------------------------------------------------------- ; This is the control break handler. It ignores the break. ;----------------------------------------------------------------------- NEWINT23 PROC FAR ASSUME DS:NOTHING, ES:NOTHING MOV CS:DIRTY_BITS,1 CLC ;Tell DOS to ignore break IRET NEWINT23 ENDP ;----------------------------------------------------------------------- ; This is the severe error handler. It homes the cursor before ; processing the error. ;----------------------------------------------------------------------- NEWINT24 PROC FAR ASSUME DS:NOTHING, ES:NOTHING PUSHF PUSH AX PUSH BX PUSH DX MOV CS:DIRTY_BITS,1 XOR DX,DX CALL SET_CURSOR ;Put cursor at home POP DX POP BX POP AX POPF JMP CS:OLDINT24 NEWINT24 ENDP ;----------------------------------------------------------------------- EVEN NAME_DOT_$$$ EQU $ NAME_DOT_BAK EQU $ + 80H UNDO_BUFFER EQU $ + 100H LINE_BUFFER EQU $ + 200H NEW_STACK EQU $ + 500H CSEG ENDS ;----------------------------------------------------------------------- FILE_SEG SEGMENT FILE_SEG ENDS END START