Software Vault: The Diamond Collection/The Diamond Collection (Software Vault)(Digital Impact).ISO/cdr48/asm32v20.zip/INPUT.DOC

Text File | 1993-12-23 | 27KB | 836 lines

********************************  INPUT  ************************************

ASM32 Input subroutines (C) Copyright 1993 Douglas Herr
all rights reserved

░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░

$EDIT:       editor module used by TEdit and GEdit.
             Must be called by GEdit or TEdit
Source:      $edit.asm (getkey.asm, isdigit.asm, toupper.asm, tolower.asm)

             TEdit and GEdit edit a string on a single row of the screen
             (without word wrap).  Strings longer than the column width of
             the screen are scrolled left or right as required.  A public
             byte in $edit's data area, EWIDTH, establishes the effective
             screen width limit.  EWIDTH is a not-to-exceed limit; if the
             actual screen width is less than EWIDTH, EWIDTH is ignored
             and the actual screen width is used instead.  ASM32's default
             EWIDTH is 132.

             $edit commands for both TEdit and GEdit are:

             Ctrl+left arrow = word left
             Ctrl+right arrow = word right
             Ctrl+end = clear to end of string
             Home = go to start of string
             End = go to end of string


             Option bits, passed to GEdit or TEdit in register AL, are:

             Option 1 = upper case input
             Option 2 = lower case input
             Option 1 OR 2 = digits only input

░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░

CLEARKEY:    clears the keyboard's 'type-ahead' buffer
             Uses BIOS functions to remove all keys in the buffer.
Source:      clearkey.asm (keywait.asm, getkey.asm)

Call with:   no parameters
Returns:     nothing
Uses:        nothing
Example:

extrn   clearkey:near

include codeseg.inc

        .
        .
        .
        call   clearkey



░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░

GEDIT:       string editor for graphics modes
             See also TEdit for text modes, $EDIT for general information
Source:      gedit.asm ($edit.asm, gprint.asm, $graph.asm, gcursor.asm,
                        gputchr.asm)

Call with:   ESI pointing to string buffer; may include a default string
             EDX pointing to x- & y-coordinates
             ECX = byte size of buffer
             AL = option bits (see $edit)
             GEdit only works with DrawMode 1 or -1 (see DrawMode in
             GRAPHICS.DOC).  GEdit forces drawmode to 1 or -1 and restores
             the previous drawmode on exit.
Returns:     AX = last key pressed (see getkey for key codes)
             ECX = new string length
Uses:        EAX, ECX, flags
Supports:    all ASM32 graphics modes
Example:

include dataseg.inc

; data
x       dw 8                      ; x-coordinate (pixels from left edge)
y       dw 100                    ; y-coordinate (pixels from top of screen)
extrn   ewidth:byte               ; byte in $edit used to limit columns
                                  ; displayed
@curseg ends

include codeseg.inc

        .
        .
        .
        mov   ewidth,40           ; there's stuff on the right side of
                                  ; the screen that should be left alone

        lea   esi,string_buffer   ; near address of string buffer
        mov   ecx,len_buffer      ; byte length of buffer for the string
        mov   al,0                ; nothing tricky
        lea   edx,x               ; point to x & y coordinates
                                  ; see GPrint for explanation of x and y
        call  gedit



░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░

GETKEY:      returns next key pressed
Source:      getkey.asm

Call with:   no parameters
Returns:     AL = ASCII key code
             AH = 0 if normal key
             AH = 1 if extended key code (such as function keys)
Uses:        AX
             Uses BIOS functions; supports enhanced keyboard if present
Supports:    standard and enhanced keyboards
Example:

extrn   getkey:near

include codeseg.inc

        .
        .
        .
        call  getkey
        shr   ah,1            ; a function key?
        jc    function_key    ; jump if so


░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░

GPICKF:      pick a file from a list of filenames
             GPickF pops a window on the screen and displays filenames
             matching an input filespec mask.  One filename may be selected
             with cursor keys or with hotkeys.  When Esc, Enter or ^C is
             pressed, GPickF restores the screen and returns the selected
             filename to the calling program.  See also MenuOption.
Source:      gpickf.asm (filelist.asm, $gpick.asm, $menu.asm, $graph.asm)

Call with:   ESI pointing to filespec mask
             BX = initial selection (0 = first filename)
             CX = file attribute mask
             EDX pointing to upper left corner of menu box
Returns:     AX = last key pressed
             EBX points to ASCIIZ filename selected
Uses:        AX, EBX
Supports:    all ASM32 graphics modes
Example:     see PICKF

░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░

GPICKSTR:    pick a string from a list of ASCIIZ strings
Source:      gpickstr.asm ($gpick.asm, $strlist.asm, $menu.asm, $graph.asm)

Call with:   ESI pointing to list of ASCIIZ strings
             BX = initial cursor position
             EDX pointing to (x,y) coordinates of upper left corner
               of selection box

             GPickStr pops a window on the screen and displays the list
             of strings.  One string may be selected with cursor keys
             or with hotkeys.  When Esc or Enter is pressed, GPickStr
             restores the screen and returns a string index number.
             See also MenuOption.  Maximum number of choices: 255

Returns:     AX = last key pressed
             EBX = string number selected (first string = 0)
Uses:        EAX, EBX, flags
Supports:    all ASM32 graphics modes
Example:     see PICKSTR


░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░

ISALPHA:     determines if a keycode returned by GetKey is a letter from
             A-Z or a-z.
Source:      isalpha.asm

Call with:   AX = keycode returned by GetKey.
Returns:     if CF = 0, keycode is a character from A-Z or a-z
             if CF = 1, keycode is not a character from A-Z or a-z
             AX is not changed
Uses:        CF
Example:     call   getkey       ; get next keystroke
             call   isalpha
             jc     not_alpha


░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░

ISDIGIT:     determines if a keycode returned by GetKey is the ASCII code
             for the numeric characters 0-9
Source:      isdigit.asm

Call with:   AX = keycode returned by GetKey.
Returns:     if CF = 0, keycode is a character from 0-9
             if CF = 1, keycode is not a character from 0-9
             AX is not changed
Uses:        CF
Example:     call   getkey       ; get next keystroke
             call   isdigit      ; I want numbers only
             jc     not_a_number



░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░

ISLOWER:     determine if a keycode returned by GetKey is lower case
Source:      islower.asm

ISUPPER:     determine if a keycode returned by GetKey is upper case
Source:      isupper.asm

Call with:   AX = keycode returned by GetKey.
Returns:     if CF = 0, keycode is a character from A-Z or a-z
             if CF = 1, keycode is not a character from A-Z or a-z
             AX is not changed
Uses:        CF
Example:     call   getkey       ; get next keystroke
             call   isupper      ; is it upper case?
             jc     not_upper    ; no; could be lower case



░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░

JANEIN:      German language version of YesNo
             waits for 'J' or 'N' key to be pressed
Source:      janein.asm

Call with:   no parameters
             Key pressed may be upper or lower case.  Upper case is
             returned.  Uses BIOS functions
Returns:     AX = 'J' or AX = 'N'
             future version will also return ^C
Uses:        AX
Example:

extrn   JaNein:near

include codeseg.inc

        .
        .
        .
        call  JaNein



░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░

KEYORBUTTON: waits for first keypress or mouse button click
Source:      mouse.asm (getkey.asm)

Call with:   no parameters
             If a keypress is waiting in the keyboard buffer before
             this subroutine is called, the keycode is returned to
             the calling program without checking mouse button status.
Returns:     AX = keycode, BX = mouse button code (see MouseStatus)
Uses:        AX, BX
Example:     call   keyorbutton


░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░

KEYWAITING:  Determines if a key is waiting in the keyboard buffer.
             Does not remove the key code from the buffer.  Uses BIOS.
Source:      keywait.asm

Call with:   no parameters
Returns:     CF = 1 if no key waiting
             CF = 0 if key waiting
Uses:        CF
Example:

extrn   keywaiting:near

include codeseg.inc

        .
        .
        .
        call   keywaiting
        jc     no_key_pressed
        call   getkey           ; get the key that was pressed


░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░

MENUOPTION:  options for PULLDOWN, PICKF, GPICKF, PICKSTR and GPICKSTR
Source:      $menu.asm

Call with:   AX = option value
             BX = option number

             If you do not specify any options or if you call MenuOption
             with AX = 0, default values are assumed.

             options available are:           defaults:
               0 = normal text color            07h
               1 = current selection color      70h
               2 = list box color               0Fh
               3 = hotkey color                 0Fh         (1)
               4 = optional quitkey             no quitkey  (2)
               5 = exit when hotkey pressed     00h         (3)
               6 = box frame type (see WFRAME)  -1          (4)

NOTE: DEFAULT COLORS MAY NOT BE SUITABLE FOR SOME GRAPHICS MODES

(1) the first upper-case letter in each string is that string's hotkey
    no upper-case character = no hotkey
(2) the quitkey value is a keycode returned by GetKey
(3) use AX = -1 for exit when hotkey pressed, AX = 0 to disable
(4) text modes only

Returns:     nothing
Uses:        nothing
Supports:    GPickF, GPickStr, PullDown, PickF, PickStr menu systems
Example:

extrn   menuoption:near, pickstr:near

include codeseg.inc

          .
          .
          .
          mov   bx,0         ; text color
          mov   ax,23        ; white w/ blue background
                             ; 16-color in graph modes, this would be
                             ; MOV  AX,0107h  (see GCOLOR in GRAPHICS.DOC)
          call  menuoption




░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░

MOUSELIMIT:  limits mouse's range of motion
Source:      mouse.asm

Call with:   EBX pointing to pixel coordinates of minimum and maximum
             x and y limits.  X-limits are the horizontal dimension and
             y-limits are the vertical dimension.
Returns:     nothing
Uses:        nothing
Example:

include dataseg.inc

x0    dw 30
y0    dw 15
x1    dw 620
y1    dw 250

@curseg ends

include codeseg.inc

       .
       .
       .
      lea    ebx,x         ; EBX points to limits
      call   mouselimit



░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░

MOUSEPOS:    sets the mouse's position
Source:      mouse.asm

Call with:   EDX pointing to desired x- and y-coordinates
             Note that mouse coordinates are expressed as a pixel location
             as with graphics mode, even if the system is in text mode
Returns:     nothing
Uses:        nothing
Example:

extrn   mousepos:near

include dataseg.inc

x     dw 100
y     dw 25

@curseg ends

include codeseg.inc

      .
      .
      .
      lea    edx,x         ; EDX points to desired position
      call   mousepos


░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░

MOUSESTATUS: determine mouse position & buttons pressed
Source:      mouse.asm

Call with:   no parameters
Returns:     if ZF = 1, no buttons are pressed
             if ZF = 0, BX = button code
              BX bit 0 if set = left button is down
              BX bit 1 if set = right button is down
              BX bit 2 if set = center button is down
             CX = horizontal (x) coordinate
             DX = vertical (y) coordinate
             Note that mouse positions are expressed as a pixel location
             as with graphics mode, even if the system is in text mode
Uses:        EBX, ECX, EDX, flags
Example:     call  mousestatus
             jz    no_buttons     ; no buttons pressed if ZF = 1



░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░

OUINON:      French language version of YesNo
             waits for 'O' or 'N' key to be pressed
Source:      ouinon.asm

Call with:   no parameters
             Key pressed may be upper or lower case.  Upper case is
             returned.  Uses BIOS functions
Returns:     AX = 'O' or AX = 'N'
             future version will also return ^C
Uses:        AX
Example:

extrn   ouinon:near

include codeseg.inc

        .
        .
        .
        call  OuiNon





░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░

PICKF:       pick a file from a list of filenames
             PickF pops a window on the screen and displays filenames
             matching an input filespec mask.  One filename may be selected
             with cursor keys or with hotkeys.  When Esc, Enter or ^C is
             pressed, PickF restores the screen and returns the selected
             filename to the calling program.

             PickF allocates a block of low memory which should be released
             after you are done with it.  See example;  See also MenuOption.
Source:      pickf.asm ($tpick.asm, filelist.asm, wsave.asm, $menu.asm)

Call with:   ESI pointing to filespec mask
             BX = initial cursor position
             CX = file attribute mask
             DH = top screen row for list
             DL = left screen column for list
Returns:     if CF = 0, AX = last key pressed
                        EBX points to filename selected
             if CF = 1, no filenames match input filespec
Uses:        AX, EBX, flags
Supports:    text mode
Example:

public  myproc
extrn   pickf:near

include dataseg.inc

filespec db '*.asm',0            ; search for ASM source code

@curseg ends

include codeseg.inc
        .
        .
        .
        lea     esi,filespec
        mov     bx,0             ; start at top of list
        xor     dx,dx            ; upper left corner of screen
        mov     cx,0             ; normal files only
        call    pickf
        cmp     ax,0Dh           ; was Enter the last key pressed?
        jne     abort            ;  nope - someone wants out


░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░

PICKSTR:     pick a string from a list of ASCIIZ strings
Source:      pickstr.asm ($tpick.asm, $strlist.asm, wsave.asm, $menu.asm)

Call with:   ESI pointing to list of ASCIIZ strings
             BX = initial cursor position
             DH = top screen row for list
             DL = left screen column for list

             PickStr pops a window on the screen and displays the list
             of strings.  One string may be selected with cursor keys
             or with hotkeys.  When Esc, Enter or ^C is pressed, PickStr
             restores the screen and returns a string index number.
             See also MenuOption.  Maximum number of choices: 255

Returns:     AX = last key pressed
             EBX = string number selected (first string = 0)
Uses:        EAX, EBX, flags
Supports:    text mode
Example:

public  myproc
extrn   pickstr:near

include dataseg.inc

string1 db 'January',0
        db 'February',0
        db 'March',0
        db 'April',0
        db 'May',0
        db 'June',0
        db 'July',0
        db 'August',0
        db 'September',0
        db 'October',0
        db 'November',0
        db 'December',0
        db 0              ; mark end of menu strings

@curseg ends

include codeseg.inc

        .
        .
        lea  esi,string1
        mov  bx,1
        xor  dx,dx
        call pickstr

░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░

PULLDOWN:    pull-down menu system
Source:      pulldown.asm ($menu.asm, tprint.asm, tputchr.asm, strlen.asm,
                           wclear.asm, wframe.asm, wsize.asm, wsave.asm,
                           getkey.asm, pickstr.asm and others)

Call with:   [ESI] pointing to menu labels
             BL = initial main menu choice, BH = initial submenu choice

             If PullDown is called with BH = 0FFh, only the main headings are
             printed initally; the submenus are printed when ENTER is
             pressed or a mouse button is pressed.

             If PullDown is called with BL <> 0FFh, it starts in the full
             main headings plus submenus mode.  In this mode, a mouse button
             click or the ENTER key will exit PullDown.  In either mode,
             ESC, ^C or the user-defined quitkey (see MenuOption) causes
             PullDown to return to the calling program.

             If there are too many main headings to fit across the top of the
             screen, the headings are scrolled left or right as required to
             show the selected heading.  Use Left, Right, Home and End keys
             to change selected headings.

             If there are too many submenu choices under a heading to fit
             on the screen, the selections are scrolled up or down as required
             to show the selected item.  Use Up, Down, PgUp, PgDown keys
             to change selection, or press highlighted letter of selection.
             Maximum number of selections per heading: 255

Returns:     BL = main menu choice, BH = submenu choice
             if CF = 1, ^C or Ctrl-Break was pressed
             if CF = 0
                 AX = 13 if ENTER was pressed
                 AX = user-defined quitkey if pressed (see MenuOption)
                 AX = 27 if ESC was pressed
                 AH = 1-7, AL = 0 if mouse button pressed
Uses:        AX, BX
Supports:    text mode; all row/column configurations supported by ASM32
             Text subroutines
Example:

see next page


;    this sample menu has 4 main menu headings:
;                          Critters, Things, Food, Trees
;    submenu choices for each main heading follow each main heading
;    Note that each string is terminated with NUL, and that there's an
;    extra NUL between the end of the submenu choices and the next main
;    heading.
;    The entire set of menu choices is terminated with 2 NUL bytes
;
;    PULLDOWN will return to the calling program when either ESCAPE or
;    ENTER is pressed (AX = ASCII code of key pressed).  PULLDOWN returns
;    AX = 0 if insufficient memory is available to save the underlying
;    screen, or AX = 3 if breaktrap was enabled and Ctrl+Break was pressed.
;
;    On return, BH = the main heading and BL = the submenu choice in effect
;    when the key was pressed.  The first main heading is number 0, and
;    the first submenu choice for each main heading is also number 0.

include model.inc

extrn   pulldown:near

include dataseg.inc
menu    db 'Critters',0
        db 'Goats',0,'Chickens',0,'Turkeys',0,'Cows',0,'Snow dogs',0

        db 0                   ; separate Things from Critters
        db 'Things',0
        db 'Computers',0,'Tractors',0,'CPU chips',0,'Barbie dolls',0

        db 0                   ; separate Food from Things
        db 'Food',0
        db 'Hot dogs',0,'Wheat germ',0,'Lasagne',0,'Cheerios',0
        db 'Potatoes',0,'chocolate chip cooKies',0

        db 0                   ; separate Trees from Food
        db 'Trees',0
        db 'giant Sequoia',0,'black Spruce',0,'Willow',0,'live Oak',0
        db 'Acacia',0,'digger Pine',0

        db 2 dup(0)            ; end of menu choices

include codeseg.inc
        .
        .
        .
        lea   esi,menu          ; point to menu labels
        xor   ebx,ebx           ; initial selection is "goats"
        call  pulldown


░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░

SINO:        Spanish language version of YesNo
             waits for 'S' or 'N' key to be pressed
Source:      sino.asm

Call with:   no parameters
             Key pressed may be upper or lower case.  Upper case is
             returned.  Uses BIOS functions
Returns:     AX = 'S' or AX = 'N'
             future version will also return ^C
Uses:        AX
Example:

extrn   sino:near

include codeseg.inc

        .
        .
        .
        call  sino


░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░

TEDIT:       ASCIIZ string editor for text modes
             See also GEdit for graphics modes, $edit for general information.
             TEdit turns the cursor off (with CursorOFF) on exit.
Source:      tedit.asm ($edit.asm, cursor.asm, a$clrw.asm, str2vbuf.asm,
                        crtinfo.asm)

Call with:   ESI pointing to string buffer; may include a default string
             ECX = byte size of buffer (excluding terminating NUL)
             AH = color attribute
             AL = option bits (see $edit)
             DH = row (offset from top of screen)
             DL = column (offset from left edge of screen)

Returns:     AX = last key pressed (see GetKey for key codes)
             ECX = new string length
Uses:        EAX, ECX, flags
Supports:    text modes; all row/column configurations
Example:

include dataseg.inc

string_buffer db 100 dup(0)
len_buffer    equ 99               ; leave one byte for terminal NUL
row           db 10
column        db 40
attr          db 12                ; color attribute

@curseg ends

include codeseg.inc
        .
        .
        .
        lea   esi,string_buffer    ; near address of string buffer
        mov   ecx,len_buffer       ; byte length of buffer for the string
        mov   dh,row
        mov   dl,column
        mov   ah,attr              ; color attribute
        mov   al,2                 ; force lower case
        call  tedit



░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░

TMOUSELIMIT: limits mouse's range of motion on text mode screen
Source:      tmlimit.asm

Call with:   DS:[BX] pointing to character coordinates of minimum and maximum
             rows and columns.  Columns are the horizontal dimension and
             rows are the vertical dimension.
Returns:     nothing
Uses:        nothing
Example:

.data

x0    dw 3          ; first row
y0    dw 1          ; first column
x1    dw 20         ; last row
y1    dw 50         ; last column

.code
; program fragment assumes DS:@DATA
       .
       .
       .
      lea    bx,x          ; DS:[BX] points to limits
      call   tmouselimit

░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░

TMOUSEPOS:   set mouse position on text-mode screen
Source:      tmouspos.asm

Call with:   DH = row (vertical position)
             DL = column (horizontal position)
Returns:     nothing
Uses:        flags
Example:

; I want to center the mouse cursor on a standard 80-column, 25-row screen

include asm.inc

extrn   tmousepos:proc

.code
        .
        .
        .
        mov    dh,12           ; close to vertical center
                               ; coordinates are 0 through 24 vertially
        mov    dl,39           ; coordinates are 0 through 79 horizontally
        call   tmousepos


░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░

TMOUSESTATUS:determine mouse position on text screen & buttons pressed
Source:      tmstatus.asm

Call with:   no parameters
             assumes mouse is installed (see IsMouse in SYSTEM.DOC)
Returns:     DH = row (vertical position)
             DL = column (horizontal position)
             if ZF = 1, no buttons are pressed
             if ZF = 0, BX = button code
              BX bit 0 if set = left button is down
              BX bit 1 if set = right button is down
              BX bit 2 if set = center button is down
Uses:        EBX, DX, flags
Example:     call  tmousestatus
             jz    no_buttons     ; no buttons pressed if ZF = 1



░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░

TOLOWER:     converts keycode returned by getkey to lower case
Source:      tolower.asm

Call with:   AX = keycode
Returns:     AX = lower case keycode
             ToLower leaves the keycode alone if the keycode is not
             upper case A-Z.
Uses:        AX
Example:     call   getkey
             call   tolower


░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░

TOUPPER:     converts keycode returned by getkey to upper case
Source:      toupper.asm

Call with:   AX = keycode
Returns:     AX = upper case keycode
             ToUpper leaves the keycode alone if the keycode is not
             lower case a-z.
Uses:        AX
Example:     call   getkey
             call   toupper


░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░

YESNO:       waits for 'Y' or 'N' key to be pressed
Source:      yesno.asm

Call with:   no parameters
             Key pressed may be upper or lower case.  Upper case is
             returned.  Uses BIOS functions
Returns:     AX = 'Y' or AX = 'N'
             future version will also return ^C
Uses:        AX
Example:

extrn   yesno:near

include codeseg.inc

        .
        .
        .
        call  yesno