Depending on the emulator, you need to be wary of multi-byte keycodes which are
used for function keys and such.
These multi-byte keycodes will begin with either CHAR(2) or CHAR(27) (for
example), but can be followed by what are otherwise printable characters. If
you do not filter them, you will get garbage in your input string if a user
presses one of those keys.
Here is a routine I use (UV with wIntegrate):
=======================
KEY.BUFR = ''
LOOP
INPUTIF JUNK, -1 THEN
KEYCODE = SEQ(KEYIN())
*
* Check for multi-byte keycodes, such as from function keys, etc.
* In wIntegrate, multi-byte keycodes begin with 2 or 27 and can be
* anywhere from 2 to 5 bytes long. Enter sub loop to gobble up all
* of the bytes. Also, special-case the ENTER key to get an immediate escape.
IF KEYCODE EQ 2 OR KEYCODE EQ 10 OR KEYCODE EQ 27 THEN
KEYSEQ = KEYCODE
LOOP
INPUTIF JUNK, -1: ELSE EXIT
KEYSEQ := SEQ(KEYIN())
REPEAT
* If it is ENTER, then exit.
IF KEYSEQ EQ 10 THEN EXIT
END ELSE
* Determine if this is a printable character, and if so,
* add it to the prompt buffer, increment the buffer count
* and exit if we have chars.
IF BITXOR(128,BITAND(255,KEYCODE + 1)) GT 160 THEN
THIS.CHAR = CHAR(KEYCODE)
PRINT '*':
KEY.BUFR := THIS.CHAR
END ELSE
* Otherwise, ignore the key, unless it is a BACKSPACE.
IF KEYCODE EQ 8 THEN
PRINT CHAR(8):' ':CHAR(8):
KEY.BUFR = KEY.BUFR[1, LEN(KEY.BUFR) -1]
END
END
END
END
* Be sure to yield to the system.
NAP 16
REPEAT
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