h6. [[FilterManager]] h6(. » [[FilterManager SWI Calls|SWI Calls]] h6((. » Filter_RegisterPreFilter h2. Filter_RegisterPreFilter h5. (SWI &42640) |_<^. Entry | | |<^. R0 |<^. Pointer to zero terminated filter name| |<^. R1 |<^. Address of [[Pre Filter Code]]| |<^. R2 |<^. Value to be passed to R12 | |<^. R3 |<^. Task handle of task to which filter is applied, or 0 for all tasks | |_<^. Exit | |<. All registers preserved| h4. Use The purpose of this call is to add a new filter to the list of pre-filters. h4. Notes The address pointed to by R1 will be called with R12 equal to the value of R2, whenever the task whose handle is passed in R3 calls Wimp_Poll. See [[Pre Filter Code]] for details of how the filter routine must behave. h4. See also * [[Filter_DeRegisterPostFilter]] * [[Filter_DeRegisterPreFilter]] * [[Filter_RegisterPostFilter]] * [[Poll Mask]] * [[Wimp_Poll]]