ted2.asm

一个很小的用汇编写的编辑器

NAME	TED
PAGE	58,132
TITLE	TED -- the Tiny EDitor
;=======================================================================
; TED.ASM -- The Tiny EDitor.
; PC Magazine * Tom Kihlken * 11/15/88
;
; See the article "The tiniest editor you'll ever need" by Tom Kihlken, 
; in the November 15, 1988 issue of PC Magazine for more detail than is 
; presented here.  Portions of this text are excerpted from that article.  
; The source listing, itself, was copied directly from that article and 
; altered as appropriate to add comments or change or improve the program.
; The use of self-modifying code for "NO_DESNOW" is discussed in the article.
; SEGment register usage have been cleaned up to reduce the size of the code.
;
; TED follows normal text conventions: pressing the <Enter> key actually 
; adds two characters, Carriage-return (ASCII 13) and Line-feed (ASCII 10), 
; also known as a "hard carriage return".  The <Tab> key inserts the ASCII 9 
; tab character, and advances the screen cursor to the next column that is 
; an even multiple of eight.  The <Backspace> key deletes the character to 
; its immediate left ("destructive" backspace) and combines two lines if it 
; is pressed while in the first column.  The Backspace code (Ctrl-H) may be 
; entered in the file as a control code.  TED2 allows the ASCII codes for 
; Carriage-Return (Ctrl-M) and Line-feed (Ctrl-J) to independently be entered 
; into the file as control codes.  Because of this, TED2 rigidly enforces 
; a convention that once the <Ctrl-M><Ctrl-J> pair is formed it becomes an 
; End-of-line marker, and may not be separated again.   
;
; Like DOS, TED lets you enter any character (except <Nul>, value 00) by 
; holding down the Alt key, typing the decimal value of its ASCII code on 
; the numeric keypad, then releasing Alt.  This gives you access both to 
; nonprinting codes below ASCII 32 and to the upper-order (ASCII 128 to 255) 
; characters in the extended IBM set.  TED2 allows the <Nul> code to be 
; entered by pressing the <Shft-F1> key.
;
; NOTE: Unassigned keyboard codes are treated as no-operations.
;
; The TED Keypad commands are:
; Key			Description
; Up Arrow		Moves cursor up one row
; Down Arrow		Moves cursor down one row
; Left Arrow		Moves cursor left one column
; Right Arrow		Moves cursor right one column
; PgUp			Moves text window up one page
; PgDn			Moves text window down one page
;>Home			Moves cursor to start of row (if at home, next up)
;>End			Moves cursor to end of row (if at end, next end down)
; Ins			Toggles insert/overstrike mode
; Del			Deletes character (right) at cursor (saved in UnDo)
; Backspace		Deletes character (left) at cursor (not saved in UnDo)
; Ctrl-PgUp		Moves to top of file
;>Ctrl-Home		Moves to top of file (alias)
; Ctrl-PgDn		Moves to bottom of file
;>Ctrl-End		Moves to bottom of file (alias)
; Ctrl-Right Arrow	Moves text window right eight columns
; Ctrl-Left Arrow	Moves text window left eight columns
;
; Alt-S	Search		Search for (case insensitive) character string
; Alt-A Search Again	Search again for string
; Alt-D	Del EOL		Deletes from cursor to the end of line
;
; The TED Editing Functions are:
; Key	Function	Operation
; F1	Help 		Help screen
; ShftF1 <Nul>		Enters the <Nul> code (value 00) in the file
; F2	Exit		Save changes and exit (creates a .BAK file)
; ShftF2 Quit		Exit without saving changes
; F3	Print		Prints the marked text
; F4	Mark		Toggles mark state on/off
; F5	Cut		Moves marked text to paste buffer
; ShftF5 Paste		Inserts contents of paste buffer (64K char's max)
; F6	Search		Search for (case insensitive) character string
; ShftF6 Search Again	Search again for string
; F7	UnDo		Replaces recently DELeted characters (256 char's max)
; F8	Del EOL		Deletes from cursor to the end of line
; ShftF8 Del L		Deletes the current line (MultiEdit)
; F9	Del L		Deletes the current line
; F10	Udel L		Inserts the last deleted line (256 char's max)
;
; In addition to the 64K Text buffer (where the edit file is maintained), 
; there are three other important buffers, as indicated above.  
;   1.) The paste buffer is a 64K character buffer used for MARK/CUT/PASTE of 
;	sections of the file.
;   2.) The line buffer is a 256 character buffer used to save the last 
; 	deleted line of text (used with F8, F9 and F10).
;   3.) The UnDo buffer is a 256 character buffer used to save the just 
;	deleted characters at the current cursor location.  It works with 
; 	the "DEL" key, but only the last character with the "Backspace" key.  
; 	It also saves overwritten characters in the Overstrike mode.  
; 	Deletions are restored with "F7" UnDo.
;
; NOTE: There is a severe subroutine nesting violation in the TED key scan 
; routine.  BAD_KEY from within the keyboard scanning loop is a junp to 
; read next key.  The BAD_KEY subroutine calls through the DISPATCH_TABLE 
; do not have a corresponding return to equalize the stack.  This was 
; partially compensated for by making the stack humongous.  TED 1.0 as 
; published in PC Magazine could eventually overflow the stack and crash the 
; system.  TED2 has corrected this problem by making a stub subroutine for 
; the DISPATCH_TABLE BAD_KEY subroutine CALLs.
;
; TED was modified by James E. Galbraith, Dec 18, 1988.
; The changes are of several types.  Compatability with other editors.  
; Correction of errors and questionable code.  Reordering of program modules 
; to make it easier to follow the listing.  Addition of meaningful comments.
; These modifications include:
;	Change F2 "UnDo" to "Exit" (for BSE compatibility).
;	Change F7 "Exit" to "UnDo".
;	Make CTRL-HOME alias to CTRL-PGUP, to home the cursor (for BSE).
;	Make CTRL-END alias to CTRL-PGDN, cursor to end of file (for BSE).
;	JMP instructions outside modules instead of CALL/RETurn are commentd.
;	Assignment of DS was sometimes ambiguous.  
;
; Modified by James E. Galbraith, June 1989.
; The changes are in two groups.  Those taken from TEDPLUS (apparently also 
; written by Tom Kihlken), which was acquired from a bulletin board service, 
; and my own changes.
;	Add SEARCH and SEARCH AGAIN as F6 and Shft-F6, from TEDPLUS.
;	Delete CPM style Ctrl-Z End-of-file code, from TEDPLUS.
;	"Enter any key code" from TEDPLUS was included, but not like TEDPLUS
;	End-of-line was changed to CR-LF as in TEDPLUS.  CR or LF codes may be 
;	  entered separately.
; My own changes are:
;	Close the source file if it has been opened.  This was not done by TED.
;	Add a HELP screen as <F1>, move QUIT to <Shft-F2>.
;	Fix the SEARCH inverse video to turn off when any key is pressed.
;	Add DOS version check, needs version 2.0 or higher to run.
;	Add a program checksum test for verification of file integrity.
;	Add <Alt-S> as alias for <F6> SEARCH (usage in BSE editor).
;	Add <Alt-A> as alias for <Shft-F6> SEARCH AGAIN (usage in BSE editor).
;	Add <Alt-D> as alias for <Shft-F8>, Delete to end of line.
;	Add <Shft-F8> as alias for <F9>, Delete Line (for future expansion).
;	If the file has not been altered, don't prompt for save or quit.
;	On QUIT, accept a CR as confirmation of intention to abandon file.
;	Add <Shft-F1> as key to enter the <Nul> character, 00.
;	If a CR and LF code are made to be ajacent, they become an EOL marker, 
;	  and may not then be separated.  This can occur in several ways that 
;	  all include entering the codes <Crtl-M> and <Ctrl-J>. 
;	A key entry will interrupt a screen update that is in progress.
;	  

; Assemble the TED2.ASM source file to TED2.COM by using the MASM.EXE assembler, 
; the linker LINK.EXE, and the file conversion utility EXE2BIN.EXE, as follows:
; The checksum byte can be obtained with TEST.BAT (included with TED2.ASM).
;
;	MASM TED2;
;	LINK TED2;
;	EXE2BIN TED2 TED2.COM
;-----------------------------------------------------------------------
CSEG		SEGMENT
		ASSUME	CS:CSEG, DS:CSEG, ES:CSEG
		ORG	0100H
START:
		JMP	BEGIN

;-----------------------------------------------------------------------
; Local data area in CSEG.
;-----------------------------------------------------------------------
; ASCII character values used in the program.
TAB		EQU	9
CR		EQU	13
LF		EQU	10
CRLF		EQU	0A0DH

; Character strings and data
COPYRIGHT	DB	"TED 1.0 (C) 1988 Ziff Communications Co.,"
		DB	"PC Magazine, 11/15/88, by Tom Kihlken"
		DB	CR,LF,"TED 2.1, 9/12/89, by James E. Galbraith"
		DB	CR,LF,"$"

		;(JEG)
HELP_SCREEN	DB	9,9,'TED - the Tiny EDitor (any key to edit)',CR
                DB      LF,LF,9,'F1 - Help',9,9,9,'Shft-F1 - <NUL> char'
		DB	CR,LF,9,'F2 - Exit and save',9,9,'Shft-F2 - Quit'
		DB	CR,LF,9,'F3 - Print marked',9,9,'Shft-F3 - Form-feed'
		DB	CR,LF,9,'F4 - Mark toggle'
		DB	CR,LF,9,'F5 - Cut marked',9,9,9,'Shft-F5 - Paste'
		DB	CR,LF,9,'F6 - String search',9,9,'Shft-F6 - '
		DB	'Search again'
		DB	CR,LF,9,'F7 - Undo <Del> or Ovr'
		DB	CR,LF,9,'F8 - Delete to EOL' ;** ,9,9,'Shft-F8 - '
	;**	DB	'Delete Line'
		DB	CR,LF,9,'F9 - Delete Line'
		DB	CR,LF,9,'F10 - Un-Delete line',LF
		DB	CR,LF,9,'Ctrl-L/R arrow - Move window'
		DB	CR,LF,9,'Ctrl-Home - to top'
		DB	CR,LF,9,'Ctrl-End - to EOF',LF
		DB	CR,LF,9,'Esc - From Exit'
		DB	CR,LF,'$',7,1AH

		;from JEG and TEDPLUS
PROMPT_STRING	DB	"1Help",0		;F1
		DB	"2Exit",0		;F2
		DB	"3Print",0		;F3
		DB	"4Mark",0		;F4
		DB	"5Cut",0		;F5
		DB	"6Search",0		;F6
		DB	"7UnDo",0		;F7
		DB	"8Del EOL",0		;F8
		DB	"9Del L",0		;F9
		DB	"10Udel L",0,0		;F10
PROMPT_LENGTH	=	$ - OFFSET PROMPT_STRING

FILE_TOO_BIG	DB	"File too big$"
READ_ERR_MESS	DB	"Read error$"
MEMORY_ERROR	DB	"Not enough memory$"

		;(JEG)
CHEK_SUM_MESS	DB	"TED altered$"
DOS_2_MESS	DB	"Needs DOS 2.0$"

VERIFY_MESS	DB	"Lose Changes (Y)?",0
SAVE_MESS	DB	"Save as: ",0
DOT_$$$		DB	".$$$",0
DOT_BAK		DB	".BAK",0

		;from TEDPLUS, string search
SRCH_PROMPT	DB	"SEARCH> ",0
;SRCH_MAX	DB	66		;(moved to file end to reduce file size)
;SRCH_SIZ	DB	0
;SRCH_STR	DB	66 DUP (0)
SRCH_FLG	DB	0		;0=normal, 1=search successful (inverse)
SRCH_END	DW	0
SRCH_BASE	DW	0
SRCH_CLR	DB	0F0H		;244

DIRTY_BITS	DB	03H		;1=update screen, 2=cursor 4=cur. line
DIRTY_FILE	DB	0		;0=file not altered, FF=file altered

NORMAL		DB	07H		;video attribute bits
INVERSE		DB	70H		;video (inverse)

LEFT_MARGIN	DB	0		;column number of screen left margin
MARGIN_COUNT	DB	0
INSERT_MODE	DB	01H		;1=INSert, 0=Overstrike, 2or3=Read Only
INSERT_CODE	DB	'OIRR'		;indexed code for display screen
MARK_MODE	DB	0		;toggle, FF=MARK is on.
ROWS		DB	23		;Rows available on display screen
SAVE_COLUMN	DB	0
SAVE_ROW	DB	0
LINE_FLAG	DB	0

EVEN					;"word align" (for 16-bit bus accesses)
NAME_POINTER	DW	81H		;offset of command tail in PSP
NAME_END	DW	81H		;end of tail

VIDEO_STATUS_REG LABEL	DWORD		;(alias for use by LES instruction)
STATUS_REG	DW	0		;video status register offset
VIDEO_SEG	DW	0B000H		;video segment, Mono=0B000, other 0B800

LINE_LENGTH	DW	0		;number of bytes in current line
UNDO_LENGTH	DW	0		;number of DELeted bytes in UnDo buffer
CURS_POSN	DW	0		;Cursor, Hi is row, Low is column

MARK_START	DW	0FFFFH		;MARK text for CUT/PASTE or Print
MARK_END	DW	0
MARK_HOME	DW	0

TOP_OF_SCREEN	DW	0		;address in text file of Top-of-screen
CURSOR		DW	0		;address in text file of cursor
LAST_CHAR	DW	0		;address of last character in file.
COLUMNSB	LABEL	BYTE		;alias BYTE definition
COLUMNS		DW	0

PASTE_SEG	DW	0		;segment address of PASTE buffer
PASTE_SIZE	DW	0		;size of block in PASTE buffer

PAGE_PROC	DW	0		;pointer used by PGUP and PGDN

EXIT_CODE	DW	4C00H		;DOS INT 21H, Func 4CH, exit with code

OLDINT24	DD	0		;pointer to DOS critical error handler

DISPATCH_BASE	EQU	59	  ;initial offset for a PASCAL type CASE list
DISPATCH_TABLE	DW	HELP	  ;59;F1, Help screen (common usage)
		DW	EXIT	  ;60;F2, Save changes and exit (from BSE)
		DW	PRINT	  ;61;F3, Print the marked text
		DW	MARK	  ;62;F4, Toggle mark state on/off
		DW	CUT	  ;63;F5, Move marked text to buffer
		DW	FIND_STR  ;64;F6, Search for text string
		DW	UNDO	  ;65;F7, Replace recently deleted chars
		DW	DEL_EOL	  ;66;F8, Delete from cursor to EOL
		DW	DEL_L	  ;67;F9, Delete the current line
		DW	UDEL_L	  ;68;F10, Insert the last deleted line
		DW	BAD_KEY	  ;69;(NumLock)
		DW	BAD_KEY	  ;70;(ScrollLock)
		DW	HOME_KEY  ;71;Home/7
		DW	UP	  ;72;Up/8
		DW	PGUP	  ;73;PgUp/9
		DW	BAD_KEY	  ;74;(-)
		DW	LEFT	  ;75;Left/4
		DW	BAD_KEY	  ;76;(5)
		DW	RIGHT	  ;77;Right/6
		DW	BAD_KEY	  ;78;(+)
		DW	END_KEY	  ;79;End/1
		DW	DOWN	  ;80;Down/2
		DW	PGDN	  ;81;PgDn/3
		DW	INSERT	  ;82;Ins/3
		DW	DEL_CHAR  ;83;Del/.

		DW	NUL_CHAR  ;84;Shft-F1 -- Add NUL character to file
		DW	ABORT	  ;85;Shft-F2 -- Quit and abandon changes
		DW	PRINT_FF  ;86;Shft-F3 -- Print a form-feed character
		DW	BAD_KEY	  ;87;Shft-F4
		DW	PASTE	  ;88;Shft-F5 -- Insert contents of Paste buffer
		DW	FIND_STR  ;89;Shft-F6 -- Search again for string
		DW	BAD_KEY	  ;90;Shft-F7
		DW	DEL_L	  ;91;Shft-F8 -- Delete line (Multi-Edit)
DISPATCH_END	EQU	92
		;--------------------------------
		; gap in keyboard scan code assignments
		;--------------------------------
DISP_CURS_BASE	EQU	115
		DW	SH_LEFT   ;115;Ctrl-Left arrow
		DW	SH_RIGHT  ;116;Ctrl-Right arrow
		DW	BOTTOM    ;117;Ctrl-End
		DW	CTRL_PGDN ;118;Ctrl-PgDn
		DW	TOP	  ;119;Ctrl-Home
DISP_CURS_END	EQU	120

;**		DW	CTRL_PGUP ;132;Ctrl-PgUp

;---------------------------------
; The following constant is a machine instruction that removes the CGA desnow 
; delay.  It is inserted into the code for EGA, VGA, and mono displays.
; See the article in PC-Magazine for further discussion.

NO_DESNOW = (OFFSET WRITE_IT - OFFSET HWAIT - 2) * 256 + 0EBH ;opcode JMP SHORT

;=======================================================================
; We start by initialize the display, then allocate memory for the file
; and paste segments.  Parse the command line for the filename, if one was 
; input, read in the file.  Finally set the INT 23 and 24 vectors.
;-----------------------------------------------------------------------
BEGIN:
		MOV	AH,30H		;get DOS version (JEG new)
		INT	21H
		CMP	AL,2
		JAE	DOS_2_UP
		MOV	EXIT_CODE,0	;is DOS version 1, exit with function 0.
		MOV	DX,OFFSET DOS_2_MESS ;message "Needs DOS 2.0"
;**short	JMP	EXIT_TO_DOS
		JMP	SHORT EXIT_22_DOS ;(saves a byte)
		;-----------------------
DOS_2_UP:
		;JEG new -- program code checksum test
		MOV	SI,100H		;start of program file.
		MOV	SP,SI		;set stack pointer to top of PSP.
		MOV	CX,OFFSET CHEK_SUM_BYT - 0100H ;size of program file.
		MOV	AL,CHEK_SUM_BYT	;load checksum correction factor byte.
CHKSUM_LOOP:	ADD	AL,[SI]		;add all program code bytes together.
		INC	SI
		LOOP	CHKSUM_LOOP
		CMP	AL,0		;is program checksum zero?
		JZ	CHEKSUM_IS_OK	;yes, continue with program
		NEG	AL		;make error into correction factor.
		MOV	BYTE PTR EXIT_CODE,AL ;save errorlevel code for exit.
		MOV	DX,OFFSET CHEK_SUM_MESS ;message "TED altered".
;**short	JMP	EXIT_TO_DOS	;error message and exit to DOS
;EXIT_22_DOS:	JMP	SHORT EXIT_2_DOS ;error message and exit to DOS
EXIT_22_DOS:	JMP	EXIT_2_DOS	;error message and exit to DOS
		;-----------------------
CHEKSUM_IS_OK:
		XOR	AX,AX
		MOV	DS,AX		;zero DS
		ASSUME	DS:NOTHING
		MOV	BL,10H
		MOV	AH,12H		;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