Wait
Reads from a hardware port with a mask.
Declare Function Wait ( ByVal port As UShort , ByVal and_mask As Integer , ByVal xor_mask As Integer = 0 ) As Integer
Wait port, and_value [, xor_value]
0 if successful, -1 on failure.
Wait keeps reading port until the reading ANDed with and_mask and optionally XORed with xor_mask gives a non-zero result.
Syntax
Declare Function Wait ( ByVal port As UShort , ByVal and_mask As Integer , ByVal xor_mask As Integer = 0 ) As Integer
Usage
Wait port, and_value [, xor_value]
Parameters
Return Value
0 if successful, -1 on failure.
Description
Wait keeps reading port until the reading ANDed with and_mask and optionally XORed with xor_mask gives a non-zero result.
Example
Wait &h3da, &h8 'Old Qbasic way of waiting for the monitor's vsync
ScreenSync 'FreeBASIC way of accomplishing the same thing
ScreenSync 'FreeBASIC way of accomplishing the same thing
Platform Differences
- In the Windows and Linux versions three port numbers (&H3C7, &H3C8, &H3C9) are hooked by the graphics library when a graphics mode is in use to emulate VGA palette handling as in QB. This use is deprecated; use Palette to retrieve and set palette colors.
- Using true port access in the Windows version requires the program to install a device driver for the present session. For that reason, Windows executables using hardware port access should be run with administrator permits each time the computer is restarted. Further runs don't require admin rights as they just use the already installed driver. The driver is only 3K in size and is embedded in the executable.
See also
