Category : BASIC Source Code
Archive   : QBFAQR01.ZIP
Filename : KEYWAIT.BAS

DEFINT A-Z

'$INCLUDE: 'QB.BI'

DECLARE FUNCTION KeyInBuf ()

'***********************************************************************
'* FUNCTION KeyInBuf
'*
'* PURPOSE
'* Uses BIOS ISR 16H, Service 01H (Report Whether Character Ready)
'* to return a keypress if one is waiting in the keyboard buffer.
'* If the key pressed is a normal key, this function will return the
'* ASCII value for that key; if the key pressed is an extended key
'* (such as F1) this function will return the ascii value for that
'* key negated. This function does not remove the key from the
'* keyboard buffer.
'*
'* EXTERNAL ROUTINE(S)
'* QBX.LIB:
'* --------
'* SUB Interrupt (IntNum, InRegs AS RegType, OutRegs AS RegType)
'***********************************************************************
FUNCTION KeyInBuf STATIC
InRegs.ax = &H100
Interrupt &H16, InRegs, OutRegs

IF ((OutRegs.flags AND 64) \ 64) = 0 THEN '0 if a key is pending
'If the key pressed is a normal key, alReg holds the ASCII code for
'that key and ahReg holds the standard PC-keyboard scan code;
'otherwise, (a special key was pressed such as F1) alReg holds 0
'and ahReg holds the character ID.
alReg = OutRegs.ax AND &HFF
ahReg = OutRegs.ax \ &HFF

IF alReg THEN
KeyInBuf = alReg
ELSE
KeyInBuf = -ahReg
END IF
ELSE
KeyInBuf = 0
END IF
END FUNCTION