Carrol Touch Modular Flat Panel Specifications download pdf (Page 193)

Appendix C - TAPI Function Reference CARROLL TOUCH

C-14 Touch System Programmer’s Guide

SetUserEventHandler (7)

Description

This function lets you install a user event handler (UEH) subroutine

that is called whenever a report is available from the driver. This lets a

user application receive reports from the TAPI driver using an interrupt

method rather than a polling method. The UEH subroutine should end

with a normal return instruction, not a return from interrupt instruction.

Once a UEH has been installed and enabled, execution of the user

program is halted and the event handler subroutine is called whenever

the TAPI driver has a report to be sent to the user, as long as the bit in

the event mask that corresponds to the type of report is set.

When the UEH is called, the CPU registers contain the following:

BX = Segment of the TAPI driver’s internal report buffer.

CX = Number of report bytes available for transfer.

DX = Offset of the TAPI driver’s internal report buffer.

The UEH may then read report bytes from the buffer, up to the number

of bytes in CX. Any bytes read from the buffer beyond the value passed

in CX are invalid. The UEH must not write to the buffer.

When the event handler subroutine returns, it must load AX as follows:

AX = 0 = Leave the TAPI driver’s internal report

buffer intact.

AX = Nonzero = Clear the TAPI driver’s internal report

buffer.

The execution of the user program then continues at the point at which

it was interrupted.

Call with

AX = 7 (function number).

BH = Event mask.

Bit 0= If 1, call handler on all coordinate reports.

Bit 1= If 1, call handler on all non-coordinate reports.

BH: X X

7 6 5 4 3 2 1 0

1 2 ... 188 189 190 191 192 193 194 195 196 197 198 ... 273 274

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Carrol Touch Modular Flat Panel Specifications Page 193