Rules for Tools/Tool Crashes
Tool crashes when processing an Event or opening for edit
The routine you provided for processing an Event or editing the Tool does not follow
the proper conventions for register usage and/or parameter passing. All parameters,
without exception, are passed as 32 bit numbers (longs.) And, when Bars&Pipes calls
your routine, it assumes you will leave all registers other than `a0', `a1', `d0' and
`d1' unchanged when done. Finally, if you are compiling with a data address base
register enabled, be sure to load it. The `geta4()' function in both Lattice and Aztec
solves this problem.