cmdedit.asm

8086汇编语言编写的文本编辑器源码,功能比较简单

	xor	ch,ch				;Clear high bits
	mov	cl,[si]				;CX<-Length of command
	jcxz	@cmdedit_cmd_98			;End of table, exit
	inc	si				;SI->command
	cmp	cx,ax				;Lengths match
	jne	@cmdedit_cmd_30			;No, go try next command
	xchg	bx,ax				;BX<-num chars in word
	call	near ptr stre_cmp		;Compare strings
	xchg	ax,bx				;AX<-num chars in word
	je	@cmdedit_cmd_50			;Command matched

@cmdedit_cmd_30:
	xor	ch,ch
	mov	cl,-1[si]			;AX<-length of command
	add	si,cx				;SI->length of next command
	inc	dx				;Increment the command number
	jmp	short @cmdedit_cmd_10		;Try next command

@cmdedit_cmd_50:				;Found command
	mov	si,di				;SI->first char of command
	add	si,ax				;SI->first char after command
	mov	cx,lastchar
	sub	cx,si				;CX<-num chars after command
	mov	di,dx				;BX<-command number
	shl	di,1				;BX<-offset into table
	call	cmd_func_table[di]		;Execute it
;						 Params:
;						 SI->first char after command
;						 CX = remaining length of line
;						 (after command)
	cmp	source,offset DGROUP:get_kbd_line
	jne	@cmdedit_cmd_60
	call	near ptr disp_prompt		;Display user prompt
@cmdedit_cmd_60:
	clc					;CF = 0
	jmp	short @cmdedit_cmd_99
@cmdedit_cmd_98:				;No command found
	stc					;CF = 1
@cmdedit_cmd_99:
	@restore
	ret
cmdedit_cmd endp




;+
; FUNCTION : abort_processing
;
;	Called by various routines in case of any errors that require
;	aborting of any ongoing processing. An error message is
;	displayed and CMDEDIT state is reset to accept input from the
;	keyboard. The routine adjusts the stack pointer to a previously
;	stored state. Execution then continues at a `abort entry'
;	point. The routine does NOT return to the caller.
;
; Parameters:
;	AX	= Error message number.
;
; Returns:
;	Does NOT return to caller.
;
; Register(s) destroyed:
;	Potentially all but irrelevant since routine does not return to
;	caller.
;-
abort_processing proc near
	mov	macro_level,0			;Reset macro level
	mov	source,offset DGROUP:get_kbd_line ;Set input to keyboard

; Display a message
	mov	si,offset DGROUP:abort_msg_hd
	mov	di,offset DGROUP:linebuf
	mov	dot,di				;dot MUST be at
;						 beginning of line
;						 since this position is
;						 stored in the main routine
	mov	cx,ABORT_HDR_LEN
	rep	movsb				;Copy message header
	sal	ax,1
	sal	ax,1				;AX is now index into msg table
	xchg	ax,bx
	mov	si,abort_msg_ptrs[bx]		;SI->message
	mov	cx,abort_msg_ptrs[bx+2]		;CX<-length of message
	rep	movsb				;Copy msg into linebuf
	mov	si,offset DGROUP:abort_msg_tl
	mov	cx,ABORT_TAIL_LEN
	rep	movsb				;Copy tail of message
	mov	lastchar,di
	mov	ax,di				;Set display marks
	mov	dx,offset DGROUP:linebuf
	call	near ptr set_disp_marks
	call	disp_line			;Display message
	call	near ptr restore_cursor		;Restore cursor to user shape
	@DispCh	CR
	@DispCh	LF
	call	near ptr disp_prompt
	mov	sp,abort_entry_stack
	jmp	near ptr cmdedit_abort_entry

abort_processing endp



;+
; FUNCTION : restore_cursor
;
;	Restores the cursor to the user's shape.
;
; Parameters:
;	Global caller_cursor contains original shape
;
; Returns:
;	
; Register(s) destroyed:
;	None.
;-
restore_cursor	proc near
	@save	ax,cx
	mov	cx,caller_cursor
	IF	TOGGLE_CURSOR
	@SetCurSz ch,cl
	ENDIF
	@restore
	ret
restore_cursor	endp


;+
; FUNCTION : reset_line
;
;	Called to init various things like cursor shape, history buffer
;	character positions etc.
;
; Parameters:
;	None.
;
; Returns:
;	Nothing.
;
; Register(s) destroyed:
;	AX,BX,CX,DX
;-
reset_line proc near
	call	near ptr hist_top	;Reset history stack ptr to top
	call	near ptr restore_cursor	;Reset cursor shape
	mov	ax,offset dgroup:linebuf
	mov	lastchar,ax		;End of line
	mov	dot,ax			;current pos in line
	mov	disp_begin,ax		;first pos that changed
	mov	disp_end,ax		;last pos that changed

; Init overstrike/insert mode
	mov	bl,default_imode	;Default edit mode
;					 (insert/overstrike) 
	mov	edit_mode,bl		;Init insert/overtype mode

; Initialize the cursor shapes for insert and overstrike mode
	mov	ax,caller_cursor	;Caller's cursor shape
	IF	TOGGLE_CURSOR
	mov	ah,al
	sub	ah,3
	mov	imode_cursor,ax		;Insert mode cursor	
	mov	ah,al
	sub	ah,1
	mov	omode_cursor,ax		;Overtype mode cursor	

; Init cursor shape
	xor	bh,bh
	add	bx,bx
	mov	cx,omode_cursor[bx]
	mov	ah,01h
	int	10h

	ELSE

	mov	omode_cursor,ax
	mov	imode_cursor,ax

	ENDIF

	mov	bh,video_page
	@GetCur bh
	mov	initial_curpos,dx	;Initial cursor position

	ret
reset_line endp


;+
; FUNCTION : init_screen
;
;	Inits various screen parameters. Reads the current prompt from
;	the screen and store in the prompt buffer. prompt buffer is
;	assumed to be at most the width of the screen.
;
; Parameters:
;	None.
;
; Returns:
;	Nothing.
; Register(s) destroyed:
;	AX,BX,CX,DX
;-
init_screen proc near
	@save	si,di
	@GetMode			;Get the video mode
	mov	video_page,bh		;Store page
	mov	screen_width,ah		; and width of display

	@GetCur	bh			;Get the cursor shape and position
	mov	initial_curpos,dx	;Initial cursor position
	mov	caller_cursor,cx	;Caller's cursor shape

	mov	di,offset DGROUP:prompt
	mov	cx,PROMPT_BUF_SIZE	;CX<-size of prompt buffer
;					 (assumed not 0)
	mov	si,dx			;DX<-cursor pos
	xor	dl,dl			;DX<-position at start of row

@init_screen_5:
; BH holds video page, DX is cursor position, SI is ending cursor
; position, CX is remaining space in prompt buffer
	@SetCurPos	,,bh		;Set cursor position
	cmp	dx,si			;Reached original position ?
	je	@init_screen_10		;Yes, all done
	@GetChAtr	bh		;Get char at cursor
	stosb				;Store in prompt buffer
	inc	dl			;Increment cursor position
	loop	@init_screen_5		;loop unless prompt buffer full
@init_screen_10:
	sub	di,offset DGROUP:prompt
	mov	prompt_length,di	;Store length of prompt

	@restore
	ret
init_screen endp



;+
; FUNCTION : disp_prompt
;
;	Called to display the user's prompt. The prompt is taken from
;	the buffer 'prompt'.
;
; Parameters:
;	None.
;
; Returns:
;	Nothing.
; Register(s) destroyed:
;	<TBA>
;-
disp_prompt	proc near
	@save	si
	@DispCh	CR
	@DispCh LF
	mov	cx,prompt_length
	jcxz	@disp_prompt_99
	mov	si,offset DGROUP:prompt
@disp_prompt_10:
	lodsb
	@DispCh	al
	loop	@disp_prompt_10
@disp_prompt_99:
	@restore
	ret
disp_prompt	endp




;+
; FUNCTION : makeroom
;
;	Called to push a specified number of characters from the end of a
;	line to the back of the line buffer.
;
; Parameters:
;	CX	- number of chars to push back
;
; Returns:
;	DI	- points to the first char of the string pushed back.
; Register(s) destroyed:
;	CX
;-
makeroom proc near
	@save	si
	mov	si,lastchar		;end of line
	dec	si
	mov	di,offset DGROUP:linebuf_suffix ;Di->end of linebuf (we
;						 want to move chars in
;						 reverse order) 
	std
	rep	movsb			;Move up characters
	cld
	inc	di			;DI->start of string
	@restore
	ret
makeroom endp


;+
; FUNCTION : getpsp
;
;	Returns the PSP of the current process
;
; Returns:
;	BX - segment of current PSP
;
; Registers destroyed :
;	AX,BX
;-
getpsp proc near
; Get the PSP of the current process
	cmp	dos_version_major,2
	jbe	@getpsp_10
;	DOS 3.x or above - use documented call
	mov	ah,62h
	jmp	short @getpsp_90
@getpsp_10:		
; DOS version 2.x - use undocumented call
	mov	ah,51h
@getpsp_90:
	int	21h				;BX->PSP segment
	ret
getpsp endp
	


;+
; Function : locate_dosenv
;
;	Locates the segment in which the current environment is located.
;	This environment is the 'current' environment which may not
;	necessarily be the root environment.
;
; Parameters:
;	None.
;
; Returns:
;	AX	- segment of environment
;
; Register(s) destroyed:
;	AX
;-
locate_dosenv proc near
	@save	bx,si,es

	call	near ptr getpsp			;BX->segment of psp
	mov	es,bx				;ES->segment of psp

;	Loop to find the current command.com psp
	mov	si,16h				;ES:SI->parent psp
	xor	ax,ax				;Init for loop
	jmp	short @locate_dosenv_20		;'while' loop
	
@locate_dosenv_10:
	mov	ax,es:[si]			;AX<-psp seg
	mov	es,ax				;ES->psp of parent
@locate_dosenv_20:
	cmp	ax,es:[si]			;Is psp == parent psp ?
	jne	@locate_dosenv_10

; ES contains DOS PSP.
	mov	ax,es:[2ch]			;Offset 2c is env address

; AX->DOS environment
;	mov	dos_envseg,ax
	cmp	dos_version_major,2		;DOS 2.x ?
	je	@locate_dosenv_50
; Versions 3.x or higher
	cmp	dos_version_minor,10		;3.1 or below ?
	jle	@locate_dosenv_50		;If so handle like 2.x
	cmp	dos_version_minor,30		;3,3 or above ?
	jge	@locate_dosenv_99		;Then all done
; DOS version higher than 3.1 but below 3.3.
	jmp	short @locate_dosenv_60


@locate_dosenv_50:
; DOS version 2.x-3.1. If the environement is non-0, all done. Else the
; environment is the memory block below the command.com.
	or	ax,ax				;0 ?
	jne	@locate_dosenv_99		;No, all done
@locate_dosenv_60:
	mov	si,es
	dec	si				;SI is segment of memory
;						 control block of command.com
	mov	es,si
	mov	ax,es:[3]			;AX->size of command.com in
;						 paragraphs 
	inc	ax				;Add size of MCB to AX (in
;						 paras) 
	add	ax,si				;AX->MCB of environment
	inc	ax				;AX->environment
;	mov	dos_envseg,ax			;Store it.

@locate_dosenv_99:
; OK, now dos_envseg supposedly contains the environment segment. DO some
; heuristics to make sure it is really what we think it is.
	

	@restore
	ret
locate_dosenv endp



;+
; FUNCTION : our_break_handler
;
;	This takes over the Ctrl-Break interrupt and sets a flag when
;	Ctrl-Break is hit. It then jumps to the original Ctrl-Break handler.
;
; Parameters:
;	
;
; Returns:
;	
; Register(s) destroyed:
;-
our_break_handler proc near
	inc	CS:check_break
	cmp	CS:trap_break,1
	jne	@our_break_handler_10
	iret
@our_break_handler_10:
	jmp	CS:prev_isr1b
our_break_handler endp

CSEG	ENDS

	END	entry