Simtel MSDOS 1992 June

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Text File | 1986-05-31 | 14.7 KB | 385 lines

name window page ,132 title BIOS Window Extension V1.1 comment \ Copyright 1984 John J. Seal The Graphic Software Company 348 East Pratt Street Franklin, IN 46131 This program may be used for any non-commercial purpose provided that this copyright notice is included. Commercial use is forbidden without the express written consent of The Graphic Software Company. This program allows a window to be defined on the display. All programs which use the BIOS Write TTY call for output will work within the window. Other BIOS calls may still be used for I/O to arbitrary screen positions. The window is defined by a pair of coordinates specified on the command line. The only absolute format requirements are that each coordinate pair start with a left parenthesis and be separated with a comma. Everything else is optional. The suggested command format is: window (ur,lc) to (lr,rc) ur = upper row lc = left column lr = lower row rc = right column The new functions serviced by the video interrupt (int 10) and their corresponding function codes are: ah = 14 Write TTY ah = 16 Set window coordinates ah = 17 Get window coordinates ah = 18 Get blanking attribute \ code segment org 100h ;For COM conversion assume cs:code DOS_entry label far ;DOS entry point jmp install upper_left label word ;Window coordinates left db 0 upper db 0 lower_right label word right db 79 lower db 24 old_int dd ? ;Old interrupt vector comment \ The new interrupt procedure first filters out the new services from the old, and passes all old service calls back to the BIOS. \ interrupt proc far sti cmp ah,14 ;Write TTY je write_tty cmp ah,16 ;Set window je set_window cmp ah,17 ;Get window je get_window cmp ah,18 ;Get blanking je get_blanking bios: jmp old_int comment \ Set window coordinates. This function call sets the coordinates of a window in the display area. The window is defined by specifying the upper left and lower right corners in terms of screen coordinates. The upper left corner of the screen is position (0,0). The specified corners are included in the window area. If the specified coordinates are legal then the window is cleared, the cursor is homed to the upper left corner, and al = 0. Otherwise, no action is taken and al = 1. Entry: ah = 16 (function code) cx = upper left corner dx = lower right corner Exit: al = fail flag (see above) All registers preserved except ax. \ set_window: push bx ;Save registers push cx push dx mov al,1 cmp ch,dh ;Check coordinates ja exit cmp cl,dl ja exit mov upper_left,cx ;Update coordinates mov lower_right,dx mov ah,18 ;Read blank attribute int 10h mov ax,600h ;Blank entire window int 10h mov ah,15 ;Read current page int 10h mov dx,cx ;Home cursor mov ah,2 int 10h mov al,0 exit: pop dx ;Restore registers pop cx pop bx iret comment \ Get window coordinates. This function call returns the coordinates of the upper left and lower right corners of the current display window. Entry: ah = 17 (function code) Exit: cx = upper left corner dx = lower right corner All registers preserved except cx and dx. \ get_window: mov cx,upper_left ;Read coordinates mov dx,lower_right iret comment \ Get blanking attribute. This function call returns the attribute of the character at the current cursor position, if in alpha mode, or the background color (0) if in graphics mode. The resulting attribute is meant to be used when scrolling the screen. Entry: ah = 18 (function code) Exit: bh = blanking attribute All registers preserved except bx. \ get_blanking: push ax ;Save registers mov ah,15 ;Read current page int 10h xor ah,ah ;Background color cmp al,3 ;Check for alpha modes jbe alpha cmp al,6 ;Check for graphics jbe graphics alpha: mov ah,8 ;Read attribute int 10h graphics: mov bh,ah ;Return attribute pop ax iret comment \ Write TTY. This function call replaces the old call of the same name. It performs the same functions but allows the current window to be user defined instead of the whole screen. Entry: ah = 14 (function code) al = character to write bh = page number to write on bl = foreground color (in graphics modes) All registers preserved. \ write_tty: cmp al,7 ;Let BIOS ring the bell je bios push ax ;Save registers push bx push cx push dx push ax ;Save character mov ah,3 ;Read cursor position int 10h pop ax ;Recover character ; Check for unprintable control characters cmp al,8 ;Backspace je bs cmp al,10 ;Line feed je lf cmp al,13 ;Carriage return je cr ; Character is printable mov cx,1 ;Print character mov ah,10 int 10h inc dl ;Advance cursor cmp dl,right jbe set_cursor ; Right edge of window exceeded - wrap to next line mov dl,left lf: inc dh cmp dh,lower jbe set_cursor ; Lower edge of window exceeded - scroll window up push bx ;Save page mov ah,18 ;Read blank attribute int 10h mov cx,upper_left ;Scroll window up mov dx,lower_right mov ax,601h int 10h pop bx ;Restore page ; Return cursor to left-hand edge cr: mov dl,left ;Carriage return ; Set cursor to new position set_cursor: mov ah,2 ;Set cursor int 10h pop dx ;Restore registers pop cx pop bx pop ax iret ; Backspace does not wrap past left edge of window bs: dec dl ;Back up cmp dl,left ;Past left edge? jb cr ;Yes, reset cursor jmp set_cursor ;No, leave it alone interrupt endp greeting db 13,10 db 218,30 dup (196),191,13,10 db 179,' The Graphic Software Company ',179,13,10 db 179,' BIOS Window Extension V1.1 ',179,13,10 db 192,30 dup (196),217,13,10,'$' error_msg db 13,10,'Invalid window coordinates',13,10,'$' comment \ The install procedure is invoked through the DOS entry point when the program is first run. It installs the new interrupt and prints a message on the console. When done, it returns to DOS and allows the space it occupies itself to be reclaimed. The program first tests whether the BIOS extensions are already installed. If they are not, this can be detected by the fact that a call to an illegal function will return without altering any registers. \ assume ds:code install proc near mov ah,17 ;Read coordinates int 10h inc cl ;Alter their value mov al,cl int 10h ;Read them again cmp al,cl ;Test for difference pushf jne installed ; Install BIOS extensions mov dx,offset greeting ;Report installation mov ah,9 int 21h mov ax,3510h ;Read old interrupt int 21h mov word ptr old_int,bx ;Save old interrupt mov word ptr old_int+2,es mov dx,offset interrupt ;Install new interrupt mov ax,2510h int 21h ; BIOS extensions are installed now installed: push cs ;Point to command tail pop es mov di,81h mov cx,7fh ;Read coordinates mov al,'(' repne scasb ;Find first pair call num_pair push dx repne scasb ;Find second pair call num_pair pop cx mov ah,16 ;Set coordinates int 10h or al,al ;Test legality jz legal ; Window coordinates are illegal mov dx,offset error_msg ;Print error message mov ah,9 int 21h ; Terminate program in appropriate manner legal: popf ;Check residency jne resident mov dx,offset greeting ;Make resident int 27h resident: int 20h ;Already resident num_pair proc near push bx call number ;Read first number mov bh,dl call number ;Read second number mov dh,bh pop bx ret ;Row/Col pair in dx num_pair endp number proc near push ax push bx mov al,' ' ;Skip leading blanks repe scasb dec di mov bl,10 ;Decimal multiplier xor ax,ax xor dx,dx digit: xchg ax,dx ;Multiply by 10 mul bl add ax,dx ;Add new digit xchg ax,dx mov al,es:[di] ;Read next character inc di sub al,'0' ;Normalize it cmp al,'9' ;Check for digits jbe digit pop bx pop ax ret ;Number in dx number endp install endp code ends end DOS_entry ;Must be far label