Specifications

Appendix D - CTKERN Function Reference CARROLL TOUCH
D-22 Touch System Programmer’s Guide
SetCalibrationMode (3)
Description
This function sets the calibration mode, which determines how the
touch coordinates reported by CTKERN are calibrated.
Call with
AL = 3 (function number).
BL = Calibration mode.
00 = Calibration disabled.
01 = Fixed calibration. This is the default.
02 = Automatic calibration.
Notes
In calibration mode 00 (disabled), the raw touch coordinates are not
calibrated before being passed on to the scaling function within the
driver.
In calibration mode 01 (fixed), the raw touch coordinates are always
calibrated using the calibration parameters of the default calibration
entry before being passed on to the scaling function within the driver.
If no calibration entry is marked as the default, the first calibration entry
(calibration table index 0) is used.
In calibration mode 02 (automatic), the raw touch coordinates are
calibrated using the calibration parameters for the currently selected
BIOS video mode. The driver determines the video mode by
intercepting calls to BIOS mode 10H function 0 (SetVideoMode). If an
entry in the table of calibration parameters that corresponds to that
video modes exists, those calibration parameters are used. If no such
entry exists, the default calibration parameters are used. If no
calibration entry is marked as the default, the first calibration entry
(calibration table index 0) is used. The calibrated coordinates are then
passed on to the scaling function within the driver.
At the time that the calibration mode is set to automatic (02), CTKERN
does a GetVideoMode BIOS call, and looks in the calibration table for
an entry that matches the currently selected video mode. If a matching
entry is found, it is used. If there is no matching entry, the default entry
is used. CTKERN then hooks the BIOS Video Interrupt (Int 10H). If the
calibration mode is subsequently changed to other than automatic, the
BIOS Video Interrupt is unhooked.